1 /*
2 * Copyright (c) 1994, 2020, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang;
27
28 import java.io.ObjectStreamField;
29 import java.io.UnsupportedEncodingException;
30 import java.lang.annotation.Native;
31 import java.lang.invoke.MethodHandles;
32 import java.lang.constant.Constable;
33 import java.lang.constant.ConstantDesc;
34 import java.nio.charset.Charset;
35 import java.util.ArrayList;
36 import java.util.Arrays;
37 import java.util.Comparator;
38 import java.util.Formatter;
39 import java.util.List;
40 import java.util.Locale;
41 import java.util.Objects;
42 import java.util.Optional;
43 import java.util.Spliterator;
44 import java.util.StringJoiner;
45 import java.util.function.Function;
46 import java.util.regex.Matcher;
47 import java.util.regex.Pattern;
48 import java.util.regex.PatternSyntaxException;
49 import java.util.stream.Collectors;
50 import java.util.stream.IntStream;
51 import java.util.stream.Stream;
52 import java.util.stream.StreamSupport;
53 import jdk.internal.HotSpotIntrinsicCandidate;
54 import jdk.internal.vm.annotation.Stable;
55
56 import static java.util.function.Predicate.not;
57
58 /**
59 * The {@code String} class represents character strings. All
60 * string literals in Java programs, such as {@code "abc"}, are
61 * implemented as instances of this class.
62 * <p>
63 * Strings are constant; their values cannot be changed after they
64 * are created. String buffers support mutable strings.
65 * Because String objects are immutable they can be shared. For example:
66 * <blockquote><pre>
67 * String str = "abc";
68 * </pre></blockquote><p>
69 * is equivalent to:
70 * <blockquote><pre>
71 * char data[] = {'a', 'b', 'c'};
72 * String str = new String(data);
73 * </pre></blockquote><p>
74 * Here are some more examples of how strings can be used:
75 * <blockquote><pre>
76 * System.out.println("abc");
77 * String cde = "cde";
78 * System.out.println("abc" + cde);
79 * String c = "abc".substring(2, 3);
80 * String d = cde.substring(1, 2);
81 * </pre></blockquote>
82 * <p>
83 * The class {@code String} includes methods for examining
84 * individual characters of the sequence, for comparing strings, for
85 * searching strings, for extracting substrings, and for creating a
86 * copy of a string with all characters translated to uppercase or to
87 * lowercase. Case mapping is based on the Unicode Standard version
88 * specified by the {@link java.lang.Character Character} class.
89 * <p>
90 * The Java language provides special support for the string
91 * concatenation operator ( + ), and for conversion of
92 * other objects to strings. For additional information on string
93 * concatenation and conversion, see <i>The Java™ Language Specification</i>.
94 *
95 * <p> Unless otherwise noted, passing a {@code null} argument to a constructor
96 * or method in this class will cause a {@link NullPointerException} to be
97 * thrown.
98 *
99 * <p>A {@code String} represents a string in the UTF-16 format
100 * in which <em>supplementary characters</em> are represented by <em>surrogate
101 * pairs</em> (see the section <a href="Character.html#unicode">Unicode
102 * Character Representations</a> in the {@code Character} class for
103 * more information).
104 * Index values refer to {@code char} code units, so a supplementary
105 * character uses two positions in a {@code String}.
106 * <p>The {@code String} class provides methods for dealing with
107 * Unicode code points (i.e., characters), in addition to those for
108 * dealing with Unicode code units (i.e., {@code char} values).
109 *
110 * <p>Unless otherwise noted, methods for comparing Strings do not take locale
111 * into account. The {@link java.text.Collator} class provides methods for
112 * finer-grain, locale-sensitive String comparison.
113 *
114 * @implNote The implementation of the string concatenation operator is left to
115 * the discretion of a Java compiler, as long as the compiler ultimately conforms
116 * to <i>The Java™ Language Specification</i>. For example, the {@code javac} compiler
117 * may implement the operator with {@code StringBuffer}, {@code StringBuilder},
118 * or {@code java.lang.invoke.StringConcatFactory} depending on the JDK version. The
119 * implementation of string conversion is typically through the method {@code toString},
120 * defined by {@code Object} and inherited by all classes in Java.
121 *
122 * @author Lee Boynton
123 * @author Arthur van Hoff
124 * @author Martin Buchholz
125 * @author Ulf Zibis
126 * @see java.lang.Object#toString()
127 * @see java.lang.StringBuffer
128 * @see java.lang.StringBuilder
129 * @see java.nio.charset.Charset
130 * @since 1.0
131 * @jls 15.18.1 String Concatenation Operator +
132 */
133
134 public final class String
135 implements java.io.Serializable, Comparable<String>, CharSequence,
136 Constable, ConstantDesc {
137
138 /**
139 * The value is used for character storage.
140 *
141 * @implNote This field is trusted by the VM, and is a subject to
142 * constant folding if String instance is constant. Overwriting this
143 * field after construction will cause problems.
144 *
145 * Additionally, it is marked with {@link Stable} to trust the contents
146 * of the array. No other facility in JDK provides this functionality (yet).
147 * {@link Stable} is safe here, because value is never null.
148 */
149 @Stable
150 private final byte[] value;
151
152 /**
153 * The identifier of the encoding used to encode the bytes in
154 * {@code value}. The supported values in this implementation are
155 *
156 * LATIN1
157 * UTF16
158 *
159 * @implNote This field is trusted by the VM, and is a subject to
160 * constant folding if String instance is constant. Overwriting this
161 * field after construction will cause problems.
162 */
163 private final byte coder;
164
165 /** Cache the hash code for the string */
166 private int hash; // Default to 0
167
168 /**
169 * Cache if the hash has been calculated as actually being zero, enabling
170 * us to avoid recalculating this.
171 */
172 private boolean hashIsZero; // Default to false;
173
174 /** use serialVersionUID from JDK 1.0.2 for interoperability */
175 @java.io.Serial
176 private static final long serialVersionUID = -6849794470754667710L;
177
178 /**
179 * If String compaction is disabled, the bytes in {@code value} are
180 * always encoded in UTF16.
181 *
182 * For methods with several possible implementation paths, when String
183 * compaction is disabled, only one code path is taken.
184 *
185 * The instance field value is generally opaque to optimizing JIT
186 * compilers. Therefore, in performance-sensitive place, an explicit
187 * check of the static boolean {@code COMPACT_STRINGS} is done first
188 * before checking the {@code coder} field since the static boolean
189 * {@code COMPACT_STRINGS} would be constant folded away by an
190 * optimizing JIT compiler. The idioms for these cases are as follows.
191 *
192 * For code such as:
193 *
194 * if (coder == LATIN1) { ... }
195 *
196 * can be written more optimally as
197 *
198 * if (coder() == LATIN1) { ... }
199 *
200 * or:
201 *
202 * if (COMPACT_STRINGS && coder == LATIN1) { ... }
203 *
204 * An optimizing JIT compiler can fold the above conditional as:
205 *
206 * COMPACT_STRINGS == true => if (coder == LATIN1) { ... }
207 * COMPACT_STRINGS == false => if (false) { ... }
208 *
209 * @implNote
210 * The actual value for this field is injected by JVM. The static
211 * initialization block is used to set the value here to communicate
212 * that this static final field is not statically foldable, and to
213 * avoid any possible circular dependency during vm initialization.
214 */
215 static final boolean COMPACT_STRINGS;
216
217 static {
218 COMPACT_STRINGS = true;
219 }
220
221 /**
222 * Class String is special cased within the Serialization Stream Protocol.
223 *
224 * A String instance is written into an ObjectOutputStream according to
225 * <a href="{@docRoot}/../specs/serialization/protocol.html#stream-elements">
226 * Object Serialization Specification, Section 6.2, "Stream Elements"</a>
227 */
228 @java.io.Serial
229 private static final ObjectStreamField[] serialPersistentFields =
230 new ObjectStreamField[0];
231
232 /**
233 * Initializes a newly created {@code String} object so that it represents
234 * an empty character sequence. Note that use of this constructor is
235 * unnecessary since Strings are immutable.
236 */
237 public String() {
238 this.value = "".value;
239 this.coder = "".coder;
240 }
241
242 /**
243 * Initializes a newly created {@code String} object so that it represents
244 * the same sequence of characters as the argument; in other words, the
245 * newly created string is a copy of the argument string. Unless an
246 * explicit copy of {@code original} is needed, use of this constructor is
247 * unnecessary since Strings are immutable.
248 *
249 * @param original
250 * A {@code String}
251 */
252 @HotSpotIntrinsicCandidate
253 public String(String original) {
254 this.value = original.value;
255 this.coder = original.coder;
256 this.hash = original.hash;
257 }
258
259 /**
260 * Allocates a new {@code String} so that it represents the sequence of
261 * characters currently contained in the character array argument. The
262 * contents of the character array are copied; subsequent modification of
263 * the character array does not affect the newly created string.
264 *
265 * @param value
266 * The initial value of the string
267 */
268 public String(char value[]) {
269 this(value, 0, value.length, null);
270 }
271
272 /**
273 * Allocates a new {@code String} that contains characters from a subarray
274 * of the character array argument. The {@code offset} argument is the
275 * index of the first character of the subarray and the {@code count}
276 * argument specifies the length of the subarray. The contents of the
277 * subarray are copied; subsequent modification of the character array does
278 * not affect the newly created string.
279 *
280 * @param value
281 * Array that is the source of characters
282 *
283 * @param offset
284 * The initial offset
285 *
286 * @param count
287 * The length
288 *
289 * @throws IndexOutOfBoundsException
290 * If {@code offset} is negative, {@code count} is negative, or
291 * {@code offset} is greater than {@code value.length - count}
292 */
293 public String(char value[], int offset, int count) {
294 this(value, offset, count, rangeCheck(value, offset, count));
295 }
296
297 private static Void rangeCheck(char[] value, int offset, int count) {
298 checkBoundsOffCount(offset, count, value.length);
299 return null;
300 }
301
302 /**
303 * Allocates a new {@code String} that contains characters from a subarray
304 * of the <a href="Character.html#unicode">Unicode code point</a> array
305 * argument. The {@code offset} argument is the index of the first code
306 * point of the subarray and the {@code count} argument specifies the
307 * length of the subarray. The contents of the subarray are converted to
308 * {@code char}s; subsequent modification of the {@code int} array does not
309 * affect the newly created string.
310 *
311 * @param codePoints
312 * Array that is the source of Unicode code points
313 *
314 * @param offset
315 * The initial offset
316 *
317 * @param count
318 * The length
319 *
320 * @throws IllegalArgumentException
321 * If any invalid Unicode code point is found in {@code
322 * codePoints}
323 *
324 * @throws IndexOutOfBoundsException
325 * If {@code offset} is negative, {@code count} is negative, or
326 * {@code offset} is greater than {@code codePoints.length - count}
327 *
328 * @since 1.5
329 */
330 public String(int[] codePoints, int offset, int count) {
331 checkBoundsOffCount(offset, count, codePoints.length);
332 if (count == 0) {
333 this.value = "".value;
334 this.coder = "".coder;
335 return;
336 }
337 if (COMPACT_STRINGS) {
338 byte[] val = StringLatin1.toBytes(codePoints, offset, count);
339 if (val != null) {
340 this.coder = LATIN1;
341 this.value = val;
342 return;
343 }
344 }
345 this.coder = UTF16;
346 this.value = StringUTF16.toBytes(codePoints, offset, count);
347 }
348
349 /**
350 * Allocates a new {@code String} constructed from a subarray of an array
351 * of 8-bit integer values.
352 *
353 * <p> The {@code offset} argument is the index of the first byte of the
354 * subarray, and the {@code count} argument specifies the length of the
355 * subarray.
356 *
357 * <p> Each {@code byte} in the subarray is converted to a {@code char} as
358 * specified in the {@link #String(byte[],int) String(byte[],int)} constructor.
359 *
360 * @deprecated This method does not properly convert bytes into characters.
361 * As of JDK 1.1, the preferred way to do this is via the
362 * {@code String} constructors that take a {@link
363 * java.nio.charset.Charset}, charset name, or that use the platform's
364 * default charset.
365 *
366 * @param ascii
367 * The bytes to be converted to characters
368 *
369 * @param hibyte
370 * The top 8 bits of each 16-bit Unicode code unit
371 *
372 * @param offset
373 * The initial offset
374 * @param count
375 * The length
376 *
377 * @throws IndexOutOfBoundsException
378 * If {@code offset} is negative, {@code count} is negative, or
379 * {@code offset} is greater than {@code ascii.length - count}
380 *
381 * @see #String(byte[], int)
382 * @see #String(byte[], int, int, java.lang.String)
383 * @see #String(byte[], int, int, java.nio.charset.Charset)
384 * @see #String(byte[], int, int)
385 * @see #String(byte[], java.lang.String)
386 * @see #String(byte[], java.nio.charset.Charset)
387 * @see #String(byte[])
388 */
389 @Deprecated(since="1.1")
390 public String(byte ascii[], int hibyte, int offset, int count) {
391 checkBoundsOffCount(offset, count, ascii.length);
392 if (count == 0) {
393 this.value = "".value;
394 this.coder = "".coder;
395 return;
396 }
397 if (COMPACT_STRINGS && (byte)hibyte == 0) {
398 this.value = Arrays.copyOfRange(ascii, offset, offset + count);
399 this.coder = LATIN1;
400 } else {
401 hibyte <<= 8;
402 byte[] val = StringUTF16.newBytesFor(count);
403 for (int i = 0; i < count; i++) {
404 StringUTF16.putChar(val, i, hibyte | (ascii[offset++] & 0xff));
405 }
406 this.value = val;
407 this.coder = UTF16;
408 }
409 }
410
411 /**
412 * Allocates a new {@code String} containing characters constructed from
413 * an array of 8-bit integer values. Each character <i>c</i> in the
414 * resulting string is constructed from the corresponding component
415 * <i>b</i> in the byte array such that:
416 *
417 * <blockquote><pre>
418 * <b><i>c</i></b> == (char)(((hibyte & 0xff) << 8)
419 * | (<b><i>b</i></b> & 0xff))
420 * </pre></blockquote>
421 *
422 * @deprecated This method does not properly convert bytes into
423 * characters. As of JDK 1.1, the preferred way to do this is via the
424 * {@code String} constructors that take a {@link
425 * java.nio.charset.Charset}, charset name, or that use the platform's
426 * default charset.
427 *
428 * @param ascii
429 * The bytes to be converted to characters
430 *
431 * @param hibyte
432 * The top 8 bits of each 16-bit Unicode code unit
433 *
434 * @see #String(byte[], int, int, java.lang.String)
435 * @see #String(byte[], int, int, java.nio.charset.Charset)
436 * @see #String(byte[], int, int)
437 * @see #String(byte[], java.lang.String)
438 * @see #String(byte[], java.nio.charset.Charset)
439 * @see #String(byte[])
440 */
441 @Deprecated(since="1.1")
442 public String(byte ascii[], int hibyte) {
443 this(ascii, hibyte, 0, ascii.length);
444 }
445
446 /**
447 * Constructs a new {@code String} by decoding the specified subarray of
448 * bytes using the specified charset. The length of the new {@code String}
449 * is a function of the charset, and hence may not be equal to the length
450 * of the subarray.
451 *
452 * <p> The behavior of this constructor when the given bytes are not valid
453 * in the given charset is unspecified. The {@link
454 * java.nio.charset.CharsetDecoder} class should be used when more control
455 * over the decoding process is required.
456 *
457 * @param bytes
458 * The bytes to be decoded into characters
459 *
460 * @param offset
461 * The index of the first byte to decode
462 *
463 * @param length
464 * The number of bytes to decode
465
466 * @param charsetName
467 * The name of a supported {@linkplain java.nio.charset.Charset
468 * charset}
469 *
470 * @throws UnsupportedEncodingException
471 * If the named charset is not supported
472 *
473 * @throws IndexOutOfBoundsException
474 * If {@code offset} is negative, {@code length} is negative, or
475 * {@code offset} is greater than {@code bytes.length - length}
476 *
477 * @since 1.1
478 */
479 public String(byte bytes[], int offset, int length, String charsetName)
480 throws UnsupportedEncodingException {
481 if (charsetName == null)
482 throw new NullPointerException("charsetName");
483 checkBoundsOffCount(offset, length, bytes.length);
484 StringCoding.Result ret =
485 StringCoding.decode(charsetName, bytes, offset, length);
486 this.value = ret.value;
487 this.coder = ret.coder;
488 }
489
490 /**
491 * Constructs a new {@code String} by decoding the specified subarray of
492 * bytes using the specified {@linkplain java.nio.charset.Charset charset}.
493 * The length of the new {@code String} is a function of the charset, and
494 * hence may not be equal to the length of the subarray.
495 *
496 * <p> This method always replaces malformed-input and unmappable-character
497 * sequences with this charset's default replacement string. The {@link
498 * java.nio.charset.CharsetDecoder} class should be used when more control
499 * over the decoding process is required.
500 *
501 * @param bytes
502 * The bytes to be decoded into characters
503 *
504 * @param offset
505 * The index of the first byte to decode
506 *
507 * @param length
508 * The number of bytes to decode
509 *
510 * @param charset
511 * The {@linkplain java.nio.charset.Charset charset} to be used to
512 * decode the {@code bytes}
513 *
514 * @throws IndexOutOfBoundsException
515 * If {@code offset} is negative, {@code length} is negative, or
516 * {@code offset} is greater than {@code bytes.length - length}
517 *
518 * @since 1.6
519 */
520 public String(byte bytes[], int offset, int length, Charset charset) {
521 if (charset == null)
522 throw new NullPointerException("charset");
523 checkBoundsOffCount(offset, length, bytes.length);
524 StringCoding.Result ret =
525 StringCoding.decode(charset, bytes, offset, length);
526 this.value = ret.value;
527 this.coder = ret.coder;
528 }
529
530 /**
531 * Constructs a new {@code String} by decoding the specified array of bytes
532 * using the specified {@linkplain java.nio.charset.Charset charset}. The
533 * length of the new {@code String} is a function of the charset, and hence
534 * may not be equal to the length of the byte array.
535 *
536 * <p> The behavior of this constructor when the given bytes are not valid
537 * in the given charset is unspecified. The {@link
538 * java.nio.charset.CharsetDecoder} class should be used when more control
539 * over the decoding process is required.
540 *
541 * @param bytes
542 * The bytes to be decoded into characters
543 *
544 * @param charsetName
545 * The name of a supported {@linkplain java.nio.charset.Charset
546 * charset}
547 *
548 * @throws UnsupportedEncodingException
549 * If the named charset is not supported
550 *
551 * @since 1.1
552 */
553 public String(byte bytes[], String charsetName)
554 throws UnsupportedEncodingException {
555 this(bytes, 0, bytes.length, charsetName);
556 }
557
558 /**
559 * Constructs a new {@code String} by decoding the specified array of
560 * bytes using the specified {@linkplain java.nio.charset.Charset charset}.
561 * The length of the new {@code String} is a function of the charset, and
562 * hence may not be equal to the length of the byte array.
563 *
564 * <p> This method always replaces malformed-input and unmappable-character
565 * sequences with this charset's default replacement string. The {@link
566 * java.nio.charset.CharsetDecoder} class should be used when more control
567 * over the decoding process is required.
568 *
569 * @param bytes
570 * The bytes to be decoded into characters
571 *
572 * @param charset
573 * The {@linkplain java.nio.charset.Charset charset} to be used to
574 * decode the {@code bytes}
575 *
576 * @since 1.6
577 */
578 public String(byte bytes[], Charset charset) {
579 this(bytes, 0, bytes.length, charset);
580 }
581
582 /**
583 * Constructs a new {@code String} by decoding the specified subarray of
584 * bytes using the platform's default charset. The length of the new
585 * {@code String} is a function of the charset, and hence may not be equal
586 * to the length of the subarray.
587 *
588 * <p> The behavior of this constructor when the given bytes are not valid
589 * in the default charset is unspecified. The {@link
590 * java.nio.charset.CharsetDecoder} class should be used when more control
591 * over the decoding process is required.
592 *
593 * @param bytes
594 * The bytes to be decoded into characters
595 *
596 * @param offset
597 * The index of the first byte to decode
598 *
599 * @param length
600 * The number of bytes to decode
601 *
602 * @throws IndexOutOfBoundsException
603 * If {@code offset} is negative, {@code length} is negative, or
604 * {@code offset} is greater than {@code bytes.length - length}
605 *
606 * @since 1.1
607 */
608 public String(byte bytes[], int offset, int length) {
609 checkBoundsOffCount(offset, length, bytes.length);
610 StringCoding.Result ret = StringCoding.decode(bytes, offset, length);
611 this.value = ret.value;
612 this.coder = ret.coder;
613 }
614
615 /**
616 * Constructs a new {@code String} by decoding the specified array of bytes
617 * using the platform's default charset. The length of the new {@code
618 * String} is a function of the charset, and hence may not be equal to the
619 * length of the byte array.
620 *
621 * <p> The behavior of this constructor when the given bytes are not valid
622 * in the default charset is unspecified. The {@link
623 * java.nio.charset.CharsetDecoder} class should be used when more control
624 * over the decoding process is required.
625 *
626 * @param bytes
627 * The bytes to be decoded into characters
628 *
629 * @since 1.1
630 */
631 public String(byte[] bytes) {
632 this(bytes, 0, bytes.length);
633 }
634
635 /**
636 * Allocates a new string that contains the sequence of characters
637 * currently contained in the string buffer argument. The contents of the
638 * string buffer are copied; subsequent modification of the string buffer
639 * does not affect the newly created string.
640 *
641 * @param buffer
642 * A {@code StringBuffer}
643 */
644 public String(StringBuffer buffer) {
645 this(buffer.toString());
646 }
647
648 /**
649 * Allocates a new string that contains the sequence of characters
650 * currently contained in the string builder argument. The contents of the
651 * string builder are copied; subsequent modification of the string builder
652 * does not affect the newly created string.
653 *
654 * <p> This constructor is provided to ease migration to {@code
655 * StringBuilder}. Obtaining a string from a string builder via the {@code
656 * toString} method is likely to run faster and is generally preferred.
657 *
658 * @param builder
659 * A {@code StringBuilder}
660 *
661 * @since 1.5
662 */
663 public String(StringBuilder builder) {
664 this(builder, null);
665 }
666
667 /**
668 * Returns the length of this string.
669 * The length is equal to the number of <a href="Character.html#unicode">Unicode
670 * code units</a> in the string.
671 *
672 * @return the length of the sequence of characters represented by this
673 * object.
674 */
675 public int length() {
676 return value.length >> coder();
677 }
678
679 /**
680 * Returns {@code true} if, and only if, {@link #length()} is {@code 0}.
681 *
682 * @return {@code true} if {@link #length()} is {@code 0}, otherwise
683 * {@code false}
684 *
685 * @since 1.6
686 */
687 public boolean isEmpty() {
688 return value.length == 0;
689 }
690
691 /**
692 * Returns the {@code char} value at the
693 * specified index. An index ranges from {@code 0} to
694 * {@code length() - 1}. The first {@code char} value of the sequence
695 * is at index {@code 0}, the next at index {@code 1},
696 * and so on, as for array indexing.
697 *
698 * <p>If the {@code char} value specified by the index is a
699 * <a href="Character.html#unicode">surrogate</a>, the surrogate
700 * value is returned.
701 *
702 * @param index the index of the {@code char} value.
703 * @return the {@code char} value at the specified index of this string.
704 * The first {@code char} value is at index {@code 0}.
705 * @throws IndexOutOfBoundsException if the {@code index}
706 * argument is negative or not less than the length of this
707 * string.
708 */
709 public char charAt(int index) {
710 if (isLatin1()) {
711 return StringLatin1.charAt(value, index);
712 } else {
713 return StringUTF16.charAt(value, index);
714 }
715 }
716
717 /**
718 * Returns the character (Unicode code point) at the specified
719 * index. The index refers to {@code char} values
720 * (Unicode code units) and ranges from {@code 0} to
721 * {@link #length()}{@code - 1}.
722 *
723 * <p> If the {@code char} value specified at the given index
724 * is in the high-surrogate range, the following index is less
725 * than the length of this {@code String}, and the
726 * {@code char} value at the following index is in the
727 * low-surrogate range, then the supplementary code point
728 * corresponding to this surrogate pair is returned. Otherwise,
729 * the {@code char} value at the given index is returned.
730 *
731 * @param index the index to the {@code char} values
732 * @return the code point value of the character at the
733 * {@code index}
734 * @throws IndexOutOfBoundsException if the {@code index}
735 * argument is negative or not less than the length of this
736 * string.
737 * @since 1.5
738 */
739 public int codePointAt(int index) {
740 if (isLatin1()) {
741 checkIndex(index, value.length);
742 return value[index] & 0xff;
743 }
744 int length = value.length >> 1;
745 checkIndex(index, length);
746 return StringUTF16.codePointAt(value, index, length);
747 }
748
749 /**
750 * Returns the character (Unicode code point) before the specified
751 * index. The index refers to {@code char} values
752 * (Unicode code units) and ranges from {@code 1} to {@link
753 * CharSequence#length() length}.
754 *
755 * <p> If the {@code char} value at {@code (index - 1)}
756 * is in the low-surrogate range, {@code (index - 2)} is not
757 * negative, and the {@code char} value at {@code (index -
758 * 2)} is in the high-surrogate range, then the
759 * supplementary code point value of the surrogate pair is
760 * returned. If the {@code char} value at {@code index -
761 * 1} is an unpaired low-surrogate or a high-surrogate, the
762 * surrogate value is returned.
763 *
764 * @param index the index following the code point that should be returned
765 * @return the Unicode code point value before the given index.
766 * @throws IndexOutOfBoundsException if the {@code index}
767 * argument is less than 1 or greater than the length
768 * of this string.
769 * @since 1.5
770 */
771 public int codePointBefore(int index) {
772 int i = index - 1;
773 if (i < 0 || i >= length()) {
774 throw new StringIndexOutOfBoundsException(index);
775 }
776 if (isLatin1()) {
777 return (value[i] & 0xff);
778 }
779 return StringUTF16.codePointBefore(value, index);
780 }
781
782 /**
783 * Returns the number of Unicode code points in the specified text
784 * range of this {@code String}. The text range begins at the
785 * specified {@code beginIndex} and extends to the
786 * {@code char} at index {@code endIndex - 1}. Thus the
787 * length (in {@code char}s) of the text range is
788 * {@code endIndex-beginIndex}. Unpaired surrogates within
789 * the text range count as one code point each.
790 *
791 * @param beginIndex the index to the first {@code char} of
792 * the text range.
793 * @param endIndex the index after the last {@code char} of
794 * the text range.
795 * @return the number of Unicode code points in the specified text
796 * range
797 * @throws IndexOutOfBoundsException if the
798 * {@code beginIndex} is negative, or {@code endIndex}
799 * is larger than the length of this {@code String}, or
800 * {@code beginIndex} is larger than {@code endIndex}.
801 * @since 1.5
802 */
803 public int codePointCount(int beginIndex, int endIndex) {
804 if (beginIndex < 0 || beginIndex > endIndex ||
805 endIndex > length()) {
806 throw new IndexOutOfBoundsException();
807 }
808 if (isLatin1()) {
809 return endIndex - beginIndex;
810 }
811 return StringUTF16.codePointCount(value, beginIndex, endIndex);
812 }
813
814 /**
815 * Returns the index within this {@code String} that is
816 * offset from the given {@code index} by
817 * {@code codePointOffset} code points. Unpaired surrogates
818 * within the text range given by {@code index} and
819 * {@code codePointOffset} count as one code point each.
820 *
821 * @param index the index to be offset
822 * @param codePointOffset the offset in code points
823 * @return the index within this {@code String}
824 * @throws IndexOutOfBoundsException if {@code index}
825 * is negative or larger then the length of this
826 * {@code String}, or if {@code codePointOffset} is positive
827 * and the substring starting with {@code index} has fewer
828 * than {@code codePointOffset} code points,
829 * or if {@code codePointOffset} is negative and the substring
830 * before {@code index} has fewer than the absolute value
831 * of {@code codePointOffset} code points.
832 * @since 1.5
833 */
834 public int offsetByCodePoints(int index, int codePointOffset) {
835 if (index < 0 || index > length()) {
836 throw new IndexOutOfBoundsException();
837 }
838 return Character.offsetByCodePoints(this, index, codePointOffset);
839 }
840
841 /**
842 * Copies characters from this string into the destination character
843 * array.
844 * <p>
845 * The first character to be copied is at index {@code srcBegin};
846 * the last character to be copied is at index {@code srcEnd-1}
847 * (thus the total number of characters to be copied is
848 * {@code srcEnd-srcBegin}). The characters are copied into the
849 * subarray of {@code dst} starting at index {@code dstBegin}
850 * and ending at index:
851 * <blockquote><pre>
852 * dstBegin + (srcEnd-srcBegin) - 1
853 * </pre></blockquote>
854 *
855 * @param srcBegin index of the first character in the string
856 * to copy.
857 * @param srcEnd index after the last character in the string
858 * to copy.
859 * @param dst the destination array.
860 * @param dstBegin the start offset in the destination array.
861 * @throws IndexOutOfBoundsException If any of the following
862 * is true:
863 * <ul><li>{@code srcBegin} is negative.
864 * <li>{@code srcBegin} is greater than {@code srcEnd}
865 * <li>{@code srcEnd} is greater than the length of this
866 * string
867 * <li>{@code dstBegin} is negative
868 * <li>{@code dstBegin+(srcEnd-srcBegin)} is larger than
869 * {@code dst.length}</ul>
870 */
871 public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin) {
872 checkBoundsBeginEnd(srcBegin, srcEnd, length());
873 checkBoundsOffCount(dstBegin, srcEnd - srcBegin, dst.length);
874 if (isLatin1()) {
875 StringLatin1.getChars(value, srcBegin, srcEnd, dst, dstBegin);
876 } else {
877 StringUTF16.getChars(value, srcBegin, srcEnd, dst, dstBegin);
878 }
879 }
880
881 /**
882 * Copies characters from this string into the destination byte array. Each
883 * byte receives the 8 low-order bits of the corresponding character. The
884 * eight high-order bits of each character are not copied and do not
885 * participate in the transfer in any way.
886 *
887 * <p> The first character to be copied is at index {@code srcBegin}; the
888 * last character to be copied is at index {@code srcEnd-1}. The total
889 * number of characters to be copied is {@code srcEnd-srcBegin}. The
890 * characters, converted to bytes, are copied into the subarray of {@code
891 * dst} starting at index {@code dstBegin} and ending at index:
892 *
893 * <blockquote><pre>
894 * dstBegin + (srcEnd-srcBegin) - 1
895 * </pre></blockquote>
896 *
897 * @deprecated This method does not properly convert characters into
898 * bytes. As of JDK 1.1, the preferred way to do this is via the
899 * {@link #getBytes()} method, which uses the platform's default charset.
900 *
901 * @param srcBegin
902 * Index of the first character in the string to copy
903 *
904 * @param srcEnd
905 * Index after the last character in the string to copy
906 *
907 * @param dst
908 * The destination array
909 *
910 * @param dstBegin
911 * The start offset in the destination array
912 *
913 * @throws IndexOutOfBoundsException
914 * If any of the following is true:
915 * <ul>
916 * <li> {@code srcBegin} is negative
917 * <li> {@code srcBegin} is greater than {@code srcEnd}
918 * <li> {@code srcEnd} is greater than the length of this String
919 * <li> {@code dstBegin} is negative
920 * <li> {@code dstBegin+(srcEnd-srcBegin)} is larger than {@code
921 * dst.length}
922 * </ul>
923 */
924 @Deprecated(since="1.1")
925 public void getBytes(int srcBegin, int srcEnd, byte dst[], int dstBegin) {
926 checkBoundsBeginEnd(srcBegin, srcEnd, length());
927 Objects.requireNonNull(dst);
928 checkBoundsOffCount(dstBegin, srcEnd - srcBegin, dst.length);
929 if (isLatin1()) {
930 StringLatin1.getBytes(value, srcBegin, srcEnd, dst, dstBegin);
931 } else {
932 StringUTF16.getBytes(value, srcBegin, srcEnd, dst, dstBegin);
933 }
934 }
935
936 /**
937 * Encodes this {@code String} into a sequence of bytes using the named
938 * charset, storing the result into a new byte array.
939 *
940 * <p> The behavior of this method when this string cannot be encoded in
941 * the given charset is unspecified. The {@link
942 * java.nio.charset.CharsetEncoder} class should be used when more control
943 * over the encoding process is required.
944 *
945 * @param charsetName
946 * The name of a supported {@linkplain java.nio.charset.Charset
947 * charset}
948 *
949 * @return The resultant byte array
950 *
951 * @throws UnsupportedEncodingException
952 * If the named charset is not supported
953 *
954 * @since 1.1
955 */
956 public byte[] getBytes(String charsetName)
957 throws UnsupportedEncodingException {
958 if (charsetName == null) throw new NullPointerException();
959 return StringCoding.encode(charsetName, coder(), value);
960 }
961
962 /**
963 * Encodes this {@code String} into a sequence of bytes using the given
964 * {@linkplain java.nio.charset.Charset charset}, storing the result into a
965 * new byte array.
966 *
967 * <p> This method always replaces malformed-input and unmappable-character
968 * sequences with this charset's default replacement byte array. The
969 * {@link java.nio.charset.CharsetEncoder} class should be used when more
970 * control over the encoding process is required.
971 *
972 * @param charset
973 * The {@linkplain java.nio.charset.Charset} to be used to encode
974 * the {@code String}
975 *
976 * @return The resultant byte array
977 *
978 * @since 1.6
979 */
980 public byte[] getBytes(Charset charset) {
981 if (charset == null) throw new NullPointerException();
982 return StringCoding.encode(charset, coder(), value);
983 }
984
985 /**
986 * Encodes this {@code String} into a sequence of bytes using the
987 * platform's default charset, storing the result into a new byte array.
988 *
989 * <p> The behavior of this method when this string cannot be encoded in
990 * the default charset is unspecified. The {@link
991 * java.nio.charset.CharsetEncoder} class should be used when more control
992 * over the encoding process is required.
993 *
994 * @return The resultant byte array
995 *
996 * @since 1.1
997 */
998 public byte[] getBytes() {
999 return StringCoding.encode(coder(), value);
1000 }
1001
1002 /**
1003 * Compares this string to the specified object. The result is {@code
1004 * true} if and only if the argument is not {@code null} and is a {@code
1005 * String} object that represents the same sequence of characters as this
1006 * object.
1007 *
1008 * <p>For finer-grained String comparison, refer to
1009 * {@link java.text.Collator}.
1010 *
1011 * @param anObject
1012 * The object to compare this {@code String} against
1013 *
1014 * @return {@code true} if the given object represents a {@code String}
1015 * equivalent to this string, {@code false} otherwise
1016 *
1017 * @see #compareTo(String)
1018 * @see #equalsIgnoreCase(String)
1019 */
1020 public boolean equals(Object anObject) {
1021 if (this == anObject) {
1022 return true;
1023 }
1024 if (anObject instanceof String) {
1025 String aString = (String)anObject;
1026 if (!COMPACT_STRINGS || this.coder == aString.coder) {
1027 return StringLatin1.equals(value, aString.value);
1028 }
1029 }
1030 return false;
1031 }
1032
1033 /**
1034 * Compares this string to the specified {@code StringBuffer}. The result
1035 * is {@code true} if and only if this {@code String} represents the same
1036 * sequence of characters as the specified {@code StringBuffer}. This method
1037 * synchronizes on the {@code StringBuffer}.
1038 *
1039 * <p>For finer-grained String comparison, refer to
1040 * {@link java.text.Collator}.
1041 *
1042 * @param sb
1043 * The {@code StringBuffer} to compare this {@code String} against
1044 *
1045 * @return {@code true} if this {@code String} represents the same
1046 * sequence of characters as the specified {@code StringBuffer},
1047 * {@code false} otherwise
1048 *
1049 * @since 1.4
1050 */
1051 public boolean contentEquals(StringBuffer sb) {
1052 return contentEquals((CharSequence)sb);
1053 }
1054
1055 private boolean nonSyncContentEquals(AbstractStringBuilder sb) {
1056 int len = length();
1057 if (len != sb.length()) {
1058 return false;
1059 }
1060 byte v1[] = value;
1061 byte v2[] = sb.getValue();
1062 byte coder = coder();
1063 if (coder == sb.getCoder()) {
1064 int n = v1.length;
1065 for (int i = 0; i < n; i++) {
1066 if (v1[i] != v2[i]) {
1067 return false;
1068 }
1069 }
1070 } else {
1071 if (coder != LATIN1) { // utf16 str and latin1 abs can never be "equal"
1072 return false;
1073 }
1074 return StringUTF16.contentEquals(v1, v2, len);
1075 }
1076 return true;
1077 }
1078
1079 /**
1080 * Compares this string to the specified {@code CharSequence}. The
1081 * result is {@code true} if and only if this {@code String} represents the
1082 * same sequence of char values as the specified sequence. Note that if the
1083 * {@code CharSequence} is a {@code StringBuffer} then the method
1084 * synchronizes on it.
1085 *
1086 * <p>For finer-grained String comparison, refer to
1087 * {@link java.text.Collator}.
1088 *
1089 * @param cs
1090 * The sequence to compare this {@code String} against
1091 *
1092 * @return {@code true} if this {@code String} represents the same
1093 * sequence of char values as the specified sequence, {@code
1094 * false} otherwise
1095 *
1096 * @since 1.5
1097 */
1098 public boolean contentEquals(CharSequence cs) {
1099 // Argument is a StringBuffer, StringBuilder
1100 if (cs instanceof AbstractStringBuilder) {
1101 if (cs instanceof StringBuffer) {
1102 synchronized(cs) {
1103 return nonSyncContentEquals((AbstractStringBuilder)cs);
1104 }
1105 } else {
1106 return nonSyncContentEquals((AbstractStringBuilder)cs);
1107 }
1108 }
1109 // Argument is a String
1110 if (cs instanceof String) {
1111 return equals(cs);
1112 }
1113 // Argument is a generic CharSequence
1114 int n = cs.length();
1115 if (n != length()) {
1116 return false;
1117 }
1118 byte[] val = this.value;
1119 if (isLatin1()) {
1120 for (int i = 0; i < n; i++) {
1121 if ((val[i] & 0xff) != cs.charAt(i)) {
1122 return false;
1123 }
1124 }
1125 } else {
1126 if (!StringUTF16.contentEquals(val, cs, n)) {
1127 return false;
1128 }
1129 }
1130 return true;
1131 }
1132
1133 /**
1134 * Compares this {@code String} to another {@code String}, ignoring case
1135 * considerations. Two strings are considered equal ignoring case if they
1136 * are of the same length and corresponding characters in the two strings
1137 * are equal ignoring case.
1138 *
1139 * <p> Two characters {@code c1} and {@code c2} are considered the same
1140 * ignoring case if at least one of the following is true:
1141 * <ul>
1142 * <li> The two characters are the same (as compared by the
1143 * {@code ==} operator)
1144 * <li> Calling {@code Character.toLowerCase(Character.toUpperCase(char))}
1145 * on each character produces the same result
1146 * </ul>
1147 *
1148 * <p>Note that this method does <em>not</em> take locale into account, and
1149 * will result in unsatisfactory results for certain locales. The
1150 * {@link java.text.Collator} class provides locale-sensitive comparison.
1151 *
1152 * @param anotherString
1153 * The {@code String} to compare this {@code String} against
1154 *
1155 * @return {@code true} if the argument is not {@code null} and it
1156 * represents an equivalent {@code String} ignoring case; {@code
1157 * false} otherwise
1158 *
1159 * @see #equals(Object)
1160 */
1161 public boolean equalsIgnoreCase(String anotherString) {
1162 return (this == anotherString) ? true
1163 : (anotherString != null)
1164 && (anotherString.length() == length())
1165 && regionMatches(true, 0, anotherString, 0, length());
1166 }
1167
1168 /**
1169 * Compares two strings lexicographically.
1170 * The comparison is based on the Unicode value of each character in
1171 * the strings. The character sequence represented by this
1172 * {@code String} object is compared lexicographically to the
1173 * character sequence represented by the argument string. The result is
1174 * a negative integer if this {@code String} object
1175 * lexicographically precedes the argument string. The result is a
1176 * positive integer if this {@code String} object lexicographically
1177 * follows the argument string. The result is zero if the strings
1178 * are equal; {@code compareTo} returns {@code 0} exactly when
1179 * the {@link #equals(Object)} method would return {@code true}.
1180 * <p>
1181 * This is the definition of lexicographic ordering. If two strings are
1182 * different, then either they have different characters at some index
1183 * that is a valid index for both strings, or their lengths are different,
1184 * or both. If they have different characters at one or more index
1185 * positions, let <i>k</i> be the smallest such index; then the string
1186 * whose character at position <i>k</i> has the smaller value, as
1187 * determined by using the {@code <} operator, lexicographically precedes the
1188 * other string. In this case, {@code compareTo} returns the
1189 * difference of the two character values at position {@code k} in
1190 * the two string -- that is, the value:
1191 * <blockquote><pre>
1192 * this.charAt(k)-anotherString.charAt(k)
1193 * </pre></blockquote>
1194 * If there is no index position at which they differ, then the shorter
1195 * string lexicographically precedes the longer string. In this case,
1196 * {@code compareTo} returns the difference of the lengths of the
1197 * strings -- that is, the value:
1198 * <blockquote><pre>
1199 * this.length()-anotherString.length()
1200 * </pre></blockquote>
1201 *
1202 * <p>For finer-grained String comparison, refer to
1203 * {@link java.text.Collator}.
1204 *
1205 * @param anotherString the {@code String} to be compared.
1206 * @return the value {@code 0} if the argument string is equal to
1207 * this string; a value less than {@code 0} if this string
1208 * is lexicographically less than the string argument; and a
1209 * value greater than {@code 0} if this string is
1210 * lexicographically greater than the string argument.
1211 */
1212 public int compareTo(String anotherString) {
1213 byte v1[] = value;
1214 byte v2[] = anotherString.value;
1215 byte coder = coder();
1216 if (coder == anotherString.coder()) {
1217 return coder == LATIN1 ? StringLatin1.compareTo(v1, v2)
1218 : StringUTF16.compareTo(v1, v2);
1219 }
1220 return coder == LATIN1 ? StringLatin1.compareToUTF16(v1, v2)
1221 : StringUTF16.compareToLatin1(v1, v2);
1222 }
1223
1224 /**
1225 * A Comparator that orders {@code String} objects as by
1226 * {@code compareToIgnoreCase}. This comparator is serializable.
1227 * <p>
1228 * Note that this Comparator does <em>not</em> take locale into account,
1229 * and will result in an unsatisfactory ordering for certain locales.
1230 * The {@link java.text.Collator} class provides locale-sensitive comparison.
1231 *
1232 * @see java.text.Collator
1233 * @since 1.2
1234 */
1235 public static final Comparator<String> CASE_INSENSITIVE_ORDER
1236 = new CaseInsensitiveComparator();
1237 private static class CaseInsensitiveComparator
1238 implements Comparator<String>, java.io.Serializable {
1239 // use serialVersionUID from JDK 1.2.2 for interoperability
1240 @java.io.Serial
1241 private static final long serialVersionUID = 8575799808933029326L;
1242
1243 public int compare(String s1, String s2) {
1244 byte v1[] = s1.value;
1245 byte v2[] = s2.value;
1246 byte coder = s1.coder();
1247 if (coder == s2.coder()) {
1248 return coder == LATIN1 ? StringLatin1.compareToCI(v1, v2)
1249 : StringUTF16.compareToCI(v1, v2);
1250 }
1251 return coder == LATIN1 ? StringLatin1.compareToCI_UTF16(v1, v2)
1252 : StringUTF16.compareToCI_Latin1(v1, v2);
1253 }
1254
1255 /** Replaces the de-serialized object. */
1256 @java.io.Serial
1257 private Object readResolve() { return CASE_INSENSITIVE_ORDER; }
1258 }
1259
1260 /**
1261 * Compares two strings lexicographically, ignoring case
1262 * differences. This method returns an integer whose sign is that of
1263 * calling {@code compareTo} with normalized versions of the strings
1264 * where case differences have been eliminated by calling
1265 * {@code Character.toLowerCase(Character.toUpperCase(character))} on
1266 * each character.
1267 * <p>
1268 * Note that this method does <em>not</em> take locale into account,
1269 * and will result in an unsatisfactory ordering for certain locales.
1270 * The {@link java.text.Collator} class provides locale-sensitive comparison.
1271 *
1272 * @param str the {@code String} to be compared.
1273 * @return a negative integer, zero, or a positive integer as the
1274 * specified String is greater than, equal to, or less
1275 * than this String, ignoring case considerations.
1276 * @see java.text.Collator
1277 * @since 1.2
1278 */
1279 public int compareToIgnoreCase(String str) {
1280 return CASE_INSENSITIVE_ORDER.compare(this, str);
1281 }
1282
1283 /**
1284 * Tests if two string regions are equal.
1285 * <p>
1286 * A substring of this {@code String} object is compared to a substring
1287 * of the argument other. The result is true if these substrings
1288 * represent identical character sequences. The substring of this
1289 * {@code String} object to be compared begins at index {@code toffset}
1290 * and has length {@code len}. The substring of other to be compared
1291 * begins at index {@code ooffset} and has length {@code len}. The
1292 * result is {@code false} if and only if at least one of the following
1293 * is true:
1294 * <ul><li>{@code toffset} is negative.
1295 * <li>{@code ooffset} is negative.
1296 * <li>{@code toffset+len} is greater than the length of this
1297 * {@code String} object.
1298 * <li>{@code ooffset+len} is greater than the length of the other
1299 * argument.
1300 * <li>There is some nonnegative integer <i>k</i> less than {@code len}
1301 * such that:
1302 * {@code this.charAt(toffset + }<i>k</i>{@code ) != other.charAt(ooffset + }
1303 * <i>k</i>{@code )}
1304 * </ul>
1305 *
1306 * <p>Note that this method does <em>not</em> take locale into account. The
1307 * {@link java.text.Collator} class provides locale-sensitive comparison.
1308 *
1309 * @param toffset the starting offset of the subregion in this string.
1310 * @param other the string argument.
1311 * @param ooffset the starting offset of the subregion in the string
1312 * argument.
1313 * @param len the number of characters to compare.
1314 * @return {@code true} if the specified subregion of this string
1315 * exactly matches the specified subregion of the string argument;
1316 * {@code false} otherwise.
1317 */
1318 public boolean regionMatches(int toffset, String other, int ooffset, int len) {
1319 byte tv[] = value;
1320 byte ov[] = other.value;
1321 // Note: toffset, ooffset, or len might be near -1>>>1.
1322 if ((ooffset < 0) || (toffset < 0) ||
1323 (toffset > (long)length() - len) ||
1324 (ooffset > (long)other.length() - len)) {
1325 return false;
1326 }
1327 byte coder = coder();
1328 if (coder == other.coder()) {
1329 if (!isLatin1() && (len > 0)) {
1330 toffset = toffset << 1;
1331 ooffset = ooffset << 1;
1332 len = len << 1;
1333 }
1334 while (len-- > 0) {
1335 if (tv[toffset++] != ov[ooffset++]) {
1336 return false;
1337 }
1338 }
1339 } else {
1340 if (coder == LATIN1) {
1341 while (len-- > 0) {
1342 if (StringLatin1.getChar(tv, toffset++) !=
1343 StringUTF16.getChar(ov, ooffset++)) {
1344 return false;
1345 }
1346 }
1347 } else {
1348 while (len-- > 0) {
1349 if (StringUTF16.getChar(tv, toffset++) !=
1350 StringLatin1.getChar(ov, ooffset++)) {
1351 return false;
1352 }
1353 }
1354 }
1355 }
1356 return true;
1357 }
1358
1359 /**
1360 * Tests if two string regions are equal.
1361 * <p>
1362 * A substring of this {@code String} object is compared to a substring
1363 * of the argument {@code other}. The result is {@code true} if these
1364 * substrings represent character sequences that are the same, ignoring
1365 * case if and only if {@code ignoreCase} is true. The substring of
1366 * this {@code String} object to be compared begins at index
1367 * {@code toffset} and has length {@code len}. The substring of
1368 * {@code other} to be compared begins at index {@code ooffset} and
1369 * has length {@code len}. The result is {@code false} if and only if
1370 * at least one of the following is true:
1371 * <ul><li>{@code toffset} is negative.
1372 * <li>{@code ooffset} is negative.
1373 * <li>{@code toffset+len} is greater than the length of this
1374 * {@code String} object.
1375 * <li>{@code ooffset+len} is greater than the length of the other
1376 * argument.
1377 * <li>{@code ignoreCase} is {@code false} and there is some nonnegative
1378 * integer <i>k</i> less than {@code len} such that:
1379 * <blockquote><pre>
1380 * this.charAt(toffset+k) != other.charAt(ooffset+k)
1381 * </pre></blockquote>
1382 * <li>{@code ignoreCase} is {@code true} and there is some nonnegative
1383 * integer <i>k</i> less than {@code len} such that:
1384 * <blockquote><pre>
1385 * Character.toLowerCase(Character.toUpperCase(this.charAt(toffset+k))) !=
1386 * Character.toLowerCase(Character.toUpperCase(other.charAt(ooffset+k)))
1387 * </pre></blockquote>
1388 * </ul>
1389 *
1390 * <p>Note that this method does <em>not</em> take locale into account,
1391 * and will result in unsatisfactory results for certain locales when
1392 * {@code ignoreCase} is {@code true}. The {@link java.text.Collator} class
1393 * provides locale-sensitive comparison.
1394 *
1395 * @param ignoreCase if {@code true}, ignore case when comparing
1396 * characters.
1397 * @param toffset the starting offset of the subregion in this
1398 * string.
1399 * @param other the string argument.
1400 * @param ooffset the starting offset of the subregion in the string
1401 * argument.
1402 * @param len the number of characters to compare.
1403 * @return {@code true} if the specified subregion of this string
1404 * matches the specified subregion of the string argument;
1405 * {@code false} otherwise. Whether the matching is exact
1406 * or case insensitive depends on the {@code ignoreCase}
1407 * argument.
1408 */
1409 public boolean regionMatches(boolean ignoreCase, int toffset,
1410 String other, int ooffset, int len) {
1411 if (!ignoreCase) {
1412 return regionMatches(toffset, other, ooffset, len);
1413 }
1414 // Note: toffset, ooffset, or len might be near -1>>>1.
1415 if ((ooffset < 0) || (toffset < 0)
1416 || (toffset > (long)length() - len)
1417 || (ooffset > (long)other.length() - len)) {
1418 return false;
1419 }
1420 byte tv[] = value;
1421 byte ov[] = other.value;
1422 byte coder = coder();
1423 if (coder == other.coder()) {
1424 return coder == LATIN1
1425 ? StringLatin1.regionMatchesCI(tv, toffset, ov, ooffset, len)
1426 : StringUTF16.regionMatchesCI(tv, toffset, ov, ooffset, len);
1427 }
1428 return coder == LATIN1
1429 ? StringLatin1.regionMatchesCI_UTF16(tv, toffset, ov, ooffset, len)
1430 : StringUTF16.regionMatchesCI_Latin1(tv, toffset, ov, ooffset, len);
1431 }
1432
1433 /**
1434 * Tests if the substring of this string beginning at the
1435 * specified index starts with the specified prefix.
1436 *
1437 * @param prefix the prefix.
1438 * @param toffset where to begin looking in this string.
1439 * @return {@code true} if the character sequence represented by the
1440 * argument is a prefix of the substring of this object starting
1441 * at index {@code toffset}; {@code false} otherwise.
1442 * The result is {@code false} if {@code toffset} is
1443 * negative or greater than the length of this
1444 * {@code String} object; otherwise the result is the same
1445 * as the result of the expression
1446 * <pre>
1447 * this.substring(toffset).startsWith(prefix)
1448 * </pre>
1449 */
1450 public boolean startsWith(String prefix, int toffset) {
1451 // Note: toffset might be near -1>>>1.
1452 if (toffset < 0 || toffset > length() - prefix.length()) {
1453 return false;
1454 }
1455 byte ta[] = value;
1456 byte pa[] = prefix.value;
1457 int po = 0;
1458 int pc = pa.length;
1459 byte coder = coder();
1460 if (coder == prefix.coder()) {
1461 int to = (coder == LATIN1) ? toffset : toffset << 1;
1462 while (po < pc) {
1463 if (ta[to++] != pa[po++]) {
1464 return false;
1465 }
1466 }
1467 } else {
1468 if (coder == LATIN1) { // && pcoder == UTF16
1469 return false;
1470 }
1471 // coder == UTF16 && pcoder == LATIN1)
1472 while (po < pc) {
1473 if (StringUTF16.getChar(ta, toffset++) != (pa[po++] & 0xff)) {
1474 return false;
1475 }
1476 }
1477 }
1478 return true;
1479 }
1480
1481 /**
1482 * Tests if this string starts with the specified prefix.
1483 *
1484 * @param prefix the prefix.
1485 * @return {@code true} if the character sequence represented by the
1486 * argument is a prefix of the character sequence represented by
1487 * this string; {@code false} otherwise.
1488 * Note also that {@code true} will be returned if the
1489 * argument is an empty string or is equal to this
1490 * {@code String} object as determined by the
1491 * {@link #equals(Object)} method.
1492 * @since 1.0
1493 */
1494 public boolean startsWith(String prefix) {
1495 return startsWith(prefix, 0);
1496 }
1497
1498 /**
1499 * Tests if this string ends with the specified suffix.
1500 *
1501 * @param suffix the suffix.
1502 * @return {@code true} if the character sequence represented by the
1503 * argument is a suffix of the character sequence represented by
1504 * this object; {@code false} otherwise. Note that the
1505 * result will be {@code true} if the argument is the
1506 * empty string or is equal to this {@code String} object
1507 * as determined by the {@link #equals(Object)} method.
1508 */
1509 public boolean endsWith(String suffix) {
1510 return startsWith(suffix, length() - suffix.length());
1511 }
1512
1513 /**
1514 * Returns a hash code for this string. The hash code for a
1515 * {@code String} object is computed as
1516 * <blockquote><pre>
1517 * s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]
1518 * </pre></blockquote>
1519 * using {@code int} arithmetic, where {@code s[i]} is the
1520 * <i>i</i>th character of the string, {@code n} is the length of
1521 * the string, and {@code ^} indicates exponentiation.
1522 * (The hash value of the empty string is zero.)
1523 *
1524 * @return a hash code value for this object.
1525 */
1526 public int hashCode() {
1527 // The hash or hashIsZero fields are subject to a benign data race,
1528 // making it crucial to ensure that any observable result of the
1529 // calculation in this method stays correct under any possible read of
1530 // these fields. Necessary restrictions to allow this to be correct
1531 // without explicit memory fences or similar concurrency primitives is
1532 // that we can ever only write to one of these two fields for a given
1533 // String instance, and that the computation is idempotent and derived
1534 // from immutable state
1535 int h = hash;
1536 if (h == 0 && !hashIsZero) {
1537 h = isLatin1() ? StringLatin1.hashCode(value)
1538 : StringUTF16.hashCode(value);
1539 if (h == 0) {
1540 hashIsZero = true;
1541 } else {
1542 hash = h;
1543 }
1544 }
1545 return h;
1546 }
1547
1548 /**
1549 * Returns the index within this string of the first occurrence of
1550 * the specified character. If a character with value
1551 * {@code ch} occurs in the character sequence represented by
1552 * this {@code String} object, then the index (in Unicode
1553 * code units) of the first such occurrence is returned. For
1554 * values of {@code ch} in the range from 0 to 0xFFFF
1555 * (inclusive), this is the smallest value <i>k</i> such that:
1556 * <blockquote><pre>
1557 * this.charAt(<i>k</i>) == ch
1558 * </pre></blockquote>
1559 * is true. For other values of {@code ch}, it is the
1560 * smallest value <i>k</i> such that:
1561 * <blockquote><pre>
1562 * this.codePointAt(<i>k</i>) == ch
1563 * </pre></blockquote>
1564 * is true. In either case, if no such character occurs in this
1565 * string, then {@code -1} is returned.
1566 *
1567 * @param ch a character (Unicode code point).
1568 * @return the index of the first occurrence of the character in the
1569 * character sequence represented by this object, or
1570 * {@code -1} if the character does not occur.
1571 */
1572 public int indexOf(int ch) {
1573 return indexOf(ch, 0);
1574 }
1575
1576 /**
1577 * Returns the index within this string of the first occurrence of the
1578 * specified character, starting the search at the specified index.
1579 * <p>
1580 * If a character with value {@code ch} occurs in the
1581 * character sequence represented by this {@code String}
1582 * object at an index no smaller than {@code fromIndex}, then
1583 * the index of the first such occurrence is returned. For values
1584 * of {@code ch} in the range from 0 to 0xFFFF (inclusive),
1585 * this is the smallest value <i>k</i> such that:
1586 * <blockquote><pre>
1587 * (this.charAt(<i>k</i>) == ch) {@code &&} (<i>k</i> >= fromIndex)
1588 * </pre></blockquote>
1589 * is true. For other values of {@code ch}, it is the
1590 * smallest value <i>k</i> such that:
1591 * <blockquote><pre>
1592 * (this.codePointAt(<i>k</i>) == ch) {@code &&} (<i>k</i> >= fromIndex)
1593 * </pre></blockquote>
1594 * is true. In either case, if no such character occurs in this
1595 * string at or after position {@code fromIndex}, then
1596 * {@code -1} is returned.
1597 *
1598 * <p>
1599 * There is no restriction on the value of {@code fromIndex}. If it
1600 * is negative, it has the same effect as if it were zero: this entire
1601 * string may be searched. If it is greater than the length of this
1602 * string, it has the same effect as if it were equal to the length of
1603 * this string: {@code -1} is returned.
1604 *
1605 * <p>All indices are specified in {@code char} values
1606 * (Unicode code units).
1607 *
1608 * @param ch a character (Unicode code point).
1609 * @param fromIndex the index to start the search from.
1610 * @return the index of the first occurrence of the character in the
1611 * character sequence represented by this object that is greater
1612 * than or equal to {@code fromIndex}, or {@code -1}
1613 * if the character does not occur.
1614 */
1615 public int indexOf(int ch, int fromIndex) {
1616 return isLatin1() ? StringLatin1.indexOf(value, ch, fromIndex)
1617 : StringUTF16.indexOf(value, ch, fromIndex);
1618 }
1619
1620 /**
1621 * Returns the index within this string of the last occurrence of
1622 * the specified character. For values of {@code ch} in the
1623 * range from 0 to 0xFFFF (inclusive), the index (in Unicode code
1624 * units) returned is the largest value <i>k</i> such that:
1625 * <blockquote><pre>
1626 * this.charAt(<i>k</i>) == ch
1627 * </pre></blockquote>
1628 * is true. For other values of {@code ch}, it is the
1629 * largest value <i>k</i> such that:
1630 * <blockquote><pre>
1631 * this.codePointAt(<i>k</i>) == ch
1632 * </pre></blockquote>
1633 * is true. In either case, if no such character occurs in this
1634 * string, then {@code -1} is returned. The
1635 * {@code String} is searched backwards starting at the last
1636 * character.
1637 *
1638 * @param ch a character (Unicode code point).
1639 * @return the index of the last occurrence of the character in the
1640 * character sequence represented by this object, or
1641 * {@code -1} if the character does not occur.
1642 */
1643 public int lastIndexOf(int ch) {
1644 return lastIndexOf(ch, length() - 1);
1645 }
1646
1647 /**
1648 * Returns the index within this string of the last occurrence of
1649 * the specified character, searching backward starting at the
1650 * specified index. For values of {@code ch} in the range
1651 * from 0 to 0xFFFF (inclusive), the index returned is the largest
1652 * value <i>k</i> such that:
1653 * <blockquote><pre>
1654 * (this.charAt(<i>k</i>) == ch) {@code &&} (<i>k</i> <= fromIndex)
1655 * </pre></blockquote>
1656 * is true. For other values of {@code ch}, it is the
1657 * largest value <i>k</i> such that:
1658 * <blockquote><pre>
1659 * (this.codePointAt(<i>k</i>) == ch) {@code &&} (<i>k</i> <= fromIndex)
1660 * </pre></blockquote>
1661 * is true. In either case, if no such character occurs in this
1662 * string at or before position {@code fromIndex}, then
1663 * {@code -1} is returned.
1664 *
1665 * <p>All indices are specified in {@code char} values
1666 * (Unicode code units).
1667 *
1668 * @param ch a character (Unicode code point).
1669 * @param fromIndex the index to start the search from. There is no
1670 * restriction on the value of {@code fromIndex}. If it is
1671 * greater than or equal to the length of this string, it has
1672 * the same effect as if it were equal to one less than the
1673 * length of this string: this entire string may be searched.
1674 * If it is negative, it has the same effect as if it were -1:
1675 * -1 is returned.
1676 * @return the index of the last occurrence of the character in the
1677 * character sequence represented by this object that is less
1678 * than or equal to {@code fromIndex}, or {@code -1}
1679 * if the character does not occur before that point.
1680 */
1681 public int lastIndexOf(int ch, int fromIndex) {
1682 return isLatin1() ? StringLatin1.lastIndexOf(value, ch, fromIndex)
1683 : StringUTF16.lastIndexOf(value, ch, fromIndex);
1684 }
1685
1686 /**
1687 * Returns the index within this string of the first occurrence of the
1688 * specified substring.
1689 *
1690 * <p>The returned index is the smallest value {@code k} for which:
1691 * <pre>{@code
1692 * this.startsWith(str, k)
1693 * }</pre>
1694 * If no such value of {@code k} exists, then {@code -1} is returned.
1695 *
1696 * @param str the substring to search for.
1697 * @return the index of the first occurrence of the specified substring,
1698 * or {@code -1} if there is no such occurrence.
1699 */
1700 public int indexOf(String str) {
1701 byte coder = coder();
1702 if (coder == str.coder()) {
1703 return isLatin1() ? StringLatin1.indexOf(value, str.value)
1704 : StringUTF16.indexOf(value, str.value);
1705 }
1706 if (coder == LATIN1) { // str.coder == UTF16
1707 return -1;
1708 }
1709 return StringUTF16.indexOfLatin1(value, str.value);
1710 }
1711
1712 /**
1713 * Returns the index within this string of the first occurrence of the
1714 * specified substring, starting at the specified index.
1715 *
1716 * <p>The returned index is the smallest value {@code k} for which:
1717 * <pre>{@code
1718 * k >= Math.min(fromIndex, this.length()) &&
1719 * this.startsWith(str, k)
1720 * }</pre>
1721 * If no such value of {@code k} exists, then {@code -1} is returned.
1722 *
1723 * @param str the substring to search for.
1724 * @param fromIndex the index from which to start the search.
1725 * @return the index of the first occurrence of the specified substring,
1726 * starting at the specified index,
1727 * or {@code -1} if there is no such occurrence.
1728 */
1729 public int indexOf(String str, int fromIndex) {
1730 return indexOf(value, coder(), length(), str, fromIndex);
1731 }
1732
1733 /**
1734 * Code shared by String and AbstractStringBuilder to do searches. The
1735 * source is the character array being searched, and the target
1736 * is the string being searched for.
1737 *
1738 * @param src the characters being searched.
1739 * @param srcCoder the coder of the source string.
1740 * @param srcCount length of the source string.
1741 * @param tgtStr the characters being searched for.
1742 * @param fromIndex the index to begin searching from.
1743 */
1744 static int indexOf(byte[] src, byte srcCoder, int srcCount,
1745 String tgtStr, int fromIndex) {
1746 byte[] tgt = tgtStr.value;
1747 byte tgtCoder = tgtStr.coder();
1748 int tgtCount = tgtStr.length();
1749
1750 if (fromIndex >= srcCount) {
1751 return (tgtCount == 0 ? srcCount : -1);
1752 }
1753 if (fromIndex < 0) {
1754 fromIndex = 0;
1755 }
1756 if (tgtCount == 0) {
1757 return fromIndex;
1758 }
1759 if (tgtCount > srcCount) {
1760 return -1;
1761 }
1762 if (srcCoder == tgtCoder) {
1763 return srcCoder == LATIN1
1764 ? StringLatin1.indexOf(src, srcCount, tgt, tgtCount, fromIndex)
1765 : StringUTF16.indexOf(src, srcCount, tgt, tgtCount, fromIndex);
1766 }
1767 if (srcCoder == LATIN1) { // && tgtCoder == UTF16
1768 return -1;
1769 }
1770 // srcCoder == UTF16 && tgtCoder == LATIN1) {
1771 return StringUTF16.indexOfLatin1(src, srcCount, tgt, tgtCount, fromIndex);
1772 }
1773
1774 /**
1775 * Returns the index within this string of the last occurrence of the
1776 * specified substring. The last occurrence of the empty string ""
1777 * is considered to occur at the index value {@code this.length()}.
1778 *
1779 * <p>The returned index is the largest value {@code k} for which:
1780 * <pre>{@code
1781 * this.startsWith(str, k)
1782 * }</pre>
1783 * If no such value of {@code k} exists, then {@code -1} is returned.
1784 *
1785 * @param str the substring to search for.
1786 * @return the index of the last occurrence of the specified substring,
1787 * or {@code -1} if there is no such occurrence.
1788 */
1789 public int lastIndexOf(String str) {
1790 return lastIndexOf(str, length());
1791 }
1792
1793 /**
1794 * Returns the index within this string of the last occurrence of the
1795 * specified substring, searching backward starting at the specified index.
1796 *
1797 * <p>The returned index is the largest value {@code k} for which:
1798 * <pre>{@code
1799 * k <= Math.min(fromIndex, this.length()) &&
1800 * this.startsWith(str, k)
1801 * }</pre>
1802 * If no such value of {@code k} exists, then {@code -1} is returned.
1803 *
1804 * @param str the substring to search for.
1805 * @param fromIndex the index to start the search from.
1806 * @return the index of the last occurrence of the specified substring,
1807 * searching backward from the specified index,
1808 * or {@code -1} if there is no such occurrence.
1809 */
1810 public int lastIndexOf(String str, int fromIndex) {
1811 return lastIndexOf(value, coder(), length(), str, fromIndex);
1812 }
1813
1814 /**
1815 * Code shared by String and AbstractStringBuilder to do searches. The
1816 * source is the character array being searched, and the target
1817 * is the string being searched for.
1818 *
1819 * @param src the characters being searched.
1820 * @param srcCoder coder handles the mapping between bytes/chars
1821 * @param srcCount count of the source string.
1822 * @param tgtStr the characters being searched for.
1823 * @param fromIndex the index to begin searching from.
1824 */
1825 static int lastIndexOf(byte[] src, byte srcCoder, int srcCount,
1826 String tgtStr, int fromIndex) {
1827 byte[] tgt = tgtStr.value;
1828 byte tgtCoder = tgtStr.coder();
1829 int tgtCount = tgtStr.length();
1830 /*
1831 * Check arguments; return immediately where possible. For
1832 * consistency, don't check for null str.
1833 */
1834 int rightIndex = srcCount - tgtCount;
1835 if (fromIndex > rightIndex) {
1836 fromIndex = rightIndex;
1837 }
1838 if (fromIndex < 0) {
1839 return -1;
1840 }
1841 /* Empty string always matches. */
1842 if (tgtCount == 0) {
1843 return fromIndex;
1844 }
1845 if (srcCoder == tgtCoder) {
1846 return srcCoder == LATIN1
1847 ? StringLatin1.lastIndexOf(src, srcCount, tgt, tgtCount, fromIndex)
1848 : StringUTF16.lastIndexOf(src, srcCount, tgt, tgtCount, fromIndex);
1849 }
1850 if (srcCoder == LATIN1) { // && tgtCoder == UTF16
1851 return -1;
1852 }
1853 // srcCoder == UTF16 && tgtCoder == LATIN1
1854 return StringUTF16.lastIndexOfLatin1(src, srcCount, tgt, tgtCount, fromIndex);
1855 }
1856
1857 /**
1858 * Returns a string that is a substring of this string. The
1859 * substring begins with the character at the specified index and
1860 * extends to the end of this string. <p>
1861 * Examples:
1862 * <blockquote><pre>
1863 * "unhappy".substring(2) returns "happy"
1864 * "Harbison".substring(3) returns "bison"
1865 * "emptiness".substring(9) returns "" (an empty string)
1866 * </pre></blockquote>
1867 *
1868 * @param beginIndex the beginning index, inclusive.
1869 * @return the specified substring.
1870 * @throws IndexOutOfBoundsException if
1871 * {@code beginIndex} is negative or larger than the
1872 * length of this {@code String} object.
1873 */
1874 public String substring(int beginIndex) {
1875 return substring(beginIndex, length());
1876 }
1877
1878 /**
1879 * Returns a string that is a substring of this string. The
1880 * substring begins at the specified {@code beginIndex} and
1881 * extends to the character at index {@code endIndex - 1}.
1882 * Thus the length of the substring is {@code endIndex-beginIndex}.
1883 * <p>
1884 * Examples:
1885 * <blockquote><pre>
1886 * "hamburger".substring(4, 8) returns "urge"
1887 * "smiles".substring(1, 5) returns "mile"
1888 * </pre></blockquote>
1889 *
1890 * @param beginIndex the beginning index, inclusive.
1891 * @param endIndex the ending index, exclusive.
1892 * @return the specified substring.
1893 * @throws IndexOutOfBoundsException if the
1894 * {@code beginIndex} is negative, or
1895 * {@code endIndex} is larger than the length of
1896 * this {@code String} object, or
1897 * {@code beginIndex} is larger than
1898 * {@code endIndex}.
1899 */
1900 public String substring(int beginIndex, int endIndex) {
1901 int length = length();
1902 checkBoundsBeginEnd(beginIndex, endIndex, length);
1903 if (beginIndex == 0 && endIndex == length) {
1904 return this;
1905 }
1906 int subLen = endIndex - beginIndex;
1907 return isLatin1() ? StringLatin1.newString(value, beginIndex, subLen)
1908 : StringUTF16.newString(value, beginIndex, subLen);
1909 }
1910
1911 /**
1912 * Returns a character sequence that is a subsequence of this sequence.
1913 *
1914 * <p> An invocation of this method of the form
1915 *
1916 * <blockquote><pre>
1917 * str.subSequence(begin, end)</pre></blockquote>
1918 *
1919 * behaves in exactly the same way as the invocation
1920 *
1921 * <blockquote><pre>
1922 * str.substring(begin, end)</pre></blockquote>
1923 *
1924 * @apiNote
1925 * This method is defined so that the {@code String} class can implement
1926 * the {@link CharSequence} interface.
1927 *
1928 * @param beginIndex the begin index, inclusive.
1929 * @param endIndex the end index, exclusive.
1930 * @return the specified subsequence.
1931 *
1932 * @throws IndexOutOfBoundsException
1933 * if {@code beginIndex} or {@code endIndex} is negative,
1934 * if {@code endIndex} is greater than {@code length()},
1935 * or if {@code beginIndex} is greater than {@code endIndex}
1936 *
1937 * @since 1.4
1938 * @spec JSR-51
1939 */
1940 public CharSequence subSequence(int beginIndex, int endIndex) {
1941 return this.substring(beginIndex, endIndex);
1942 }
1943
1944 /**
1945 * Concatenates the specified string to the end of this string.
1946 * <p>
1947 * If the length of the argument string is {@code 0}, then this
1948 * {@code String} object is returned. Otherwise, a
1949 * {@code String} object is returned that represents a character
1950 * sequence that is the concatenation of the character sequence
1951 * represented by this {@code String} object and the character
1952 * sequence represented by the argument string.<p>
1953 * Examples:
1954 * <blockquote><pre>
1955 * "cares".concat("s") returns "caress"
1956 * "to".concat("get").concat("her") returns "together"
1957 * </pre></blockquote>
1958 *
1959 * @param str the {@code String} that is concatenated to the end
1960 * of this {@code String}.
1961 * @return a string that represents the concatenation of this object's
1962 * characters followed by the string argument's characters.
1963 */
1964 public String concat(String str) {
1965 if (str.isEmpty()) {
1966 return this;
1967 }
1968 return StringConcatHelper.simpleConcat(this, str);
1969 }
1970
1971 /**
1972 * Returns a string resulting from replacing all occurrences of
1973 * {@code oldChar} in this string with {@code newChar}.
1974 * <p>
1975 * If the character {@code oldChar} does not occur in the
1976 * character sequence represented by this {@code String} object,
1977 * then a reference to this {@code String} object is returned.
1978 * Otherwise, a {@code String} object is returned that
1979 * represents a character sequence identical to the character sequence
1980 * represented by this {@code String} object, except that every
1981 * occurrence of {@code oldChar} is replaced by an occurrence
1982 * of {@code newChar}.
1983 * <p>
1984 * Examples:
1985 * <blockquote><pre>
1986 * "mesquite in your cellar".replace('e', 'o')
1987 * returns "mosquito in your collar"
1988 * "the war of baronets".replace('r', 'y')
1989 * returns "the way of bayonets"
1990 * "sparring with a purple porpoise".replace('p', 't')
1991 * returns "starring with a turtle tortoise"
1992 * "JonL".replace('q', 'x') returns "JonL" (no change)
1993 * </pre></blockquote>
1994 *
1995 * @param oldChar the old character.
1996 * @param newChar the new character.
1997 * @return a string derived from this string by replacing every
1998 * occurrence of {@code oldChar} with {@code newChar}.
1999 */
2000 public String replace(char oldChar, char newChar) {
2001 if (oldChar != newChar) {
2002 String ret = isLatin1() ? StringLatin1.replace(value, oldChar, newChar)
2003 : StringUTF16.replace(value, oldChar, newChar);
2004 if (ret != null) {
2005 return ret;
2006 }
2007 }
2008 return this;
2009 }
2010
2011 /**
2012 * Tells whether or not this string matches the given <a
2013 * href="../util/regex/Pattern.html#sum">regular expression</a>.
2014 *
2015 * <p> An invocation of this method of the form
2016 * <i>str</i>{@code .matches(}<i>regex</i>{@code )} yields exactly the
2017 * same result as the expression
2018 *
2019 * <blockquote>
2020 * {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#matches(String,CharSequence)
2021 * matches(<i>regex</i>, <i>str</i>)}
2022 * </blockquote>
2023 *
2024 * @param regex
2025 * the regular expression to which this string is to be matched
2026 *
2027 * @return {@code true} if, and only if, this string matches the
2028 * given regular expression
2029 *
2030 * @throws PatternSyntaxException
2031 * if the regular expression's syntax is invalid
2032 *
2033 * @see java.util.regex.Pattern
2034 *
2035 * @since 1.4
2036 * @spec JSR-51
2037 */
2038 public boolean matches(String regex) {
2039 return Pattern.matches(regex, this);
2040 }
2041
2042 /**
2043 * Returns true if and only if this string contains the specified
2044 * sequence of char values.
2045 *
2046 * @param s the sequence to search for
2047 * @return true if this string contains {@code s}, false otherwise
2048 * @since 1.5
2049 */
2050 public boolean contains(CharSequence s) {
2051 return indexOf(s.toString()) >= 0;
2052 }
2053
2054 /**
2055 * Replaces the first substring of this string that matches the given <a
2056 * href="../util/regex/Pattern.html#sum">regular expression</a> with the
2057 * given replacement.
2058 *
2059 * <p> An invocation of this method of the form
2060 * <i>str</i>{@code .replaceFirst(}<i>regex</i>{@code ,} <i>repl</i>{@code )}
2061 * yields exactly the same result as the expression
2062 *
2063 * <blockquote>
2064 * <code>
2065 * {@link java.util.regex.Pattern}.{@link
2066 * java.util.regex.Pattern#compile compile}(<i>regex</i>).{@link
2067 * java.util.regex.Pattern#matcher(java.lang.CharSequence) matcher}(<i>str</i>).{@link
2068 * java.util.regex.Matcher#replaceFirst replaceFirst}(<i>repl</i>)
2069 * </code>
2070 * </blockquote>
2071 *
2072 *<p>
2073 * Note that backslashes ({@code \}) and dollar signs ({@code $}) in the
2074 * replacement string may cause the results to be different than if it were
2075 * being treated as a literal replacement string; see
2076 * {@link java.util.regex.Matcher#replaceFirst}.
2077 * Use {@link java.util.regex.Matcher#quoteReplacement} to suppress the special
2078 * meaning of these characters, if desired.
2079 *
2080 * @param regex
2081 * the regular expression to which this string is to be matched
2082 * @param replacement
2083 * the string to be substituted for the first match
2084 *
2085 * @return The resulting {@code String}
2086 *
2087 * @throws PatternSyntaxException
2088 * if the regular expression's syntax is invalid
2089 *
2090 * @see java.util.regex.Pattern
2091 *
2092 * @since 1.4
2093 * @spec JSR-51
2094 */
2095 public String replaceFirst(String regex, String replacement) {
2096 return Pattern.compile(regex).matcher(this).replaceFirst(replacement);
2097 }
2098
2099 /**
2100 * Replaces each substring of this string that matches the given <a
2101 * href="../util/regex/Pattern.html#sum">regular expression</a> with the
2102 * given replacement.
2103 *
2104 * <p> An invocation of this method of the form
2105 * <i>str</i>{@code .replaceAll(}<i>regex</i>{@code ,} <i>repl</i>{@code )}
2106 * yields exactly the same result as the expression
2107 *
2108 * <blockquote>
2109 * <code>
2110 * {@link java.util.regex.Pattern}.{@link
2111 * java.util.regex.Pattern#compile compile}(<i>regex</i>).{@link
2112 * java.util.regex.Pattern#matcher(java.lang.CharSequence) matcher}(<i>str</i>).{@link
2113 * java.util.regex.Matcher#replaceAll replaceAll}(<i>repl</i>)
2114 * </code>
2115 * </blockquote>
2116 *
2117 *<p>
2118 * Note that backslashes ({@code \}) and dollar signs ({@code $}) in the
2119 * replacement string may cause the results to be different than if it were
2120 * being treated as a literal replacement string; see
2121 * {@link java.util.regex.Matcher#replaceAll Matcher.replaceAll}.
2122 * Use {@link java.util.regex.Matcher#quoteReplacement} to suppress the special
2123 * meaning of these characters, if desired.
2124 *
2125 * @param regex
2126 * the regular expression to which this string is to be matched
2127 * @param replacement
2128 * the string to be substituted for each match
2129 *
2130 * @return The resulting {@code String}
2131 *
2132 * @throws PatternSyntaxException
2133 * if the regular expression's syntax is invalid
2134 *
2135 * @see java.util.regex.Pattern
2136 *
2137 * @since 1.4
2138 * @spec JSR-51
2139 */
2140 public String replaceAll(String regex, String replacement) {
2141 return Pattern.compile(regex).matcher(this).replaceAll(replacement);
2142 }
2143
2144 /**
2145 * Replaces each substring of this string that matches the literal target
2146 * sequence with the specified literal replacement sequence. The
2147 * replacement proceeds from the beginning of the string to the end, for
2148 * example, replacing "aa" with "b" in the string "aaa" will result in
2149 * "ba" rather than "ab".
2150 *
2151 * @param target The sequence of char values to be replaced
2152 * @param replacement The replacement sequence of char values
2153 * @return The resulting string
2154 * @since 1.5
2155 */
2156 public String replace(CharSequence target, CharSequence replacement) {
2157 String trgtStr = target.toString();
2158 String replStr = replacement.toString();
2159 int thisLen = length();
2160 int trgtLen = trgtStr.length();
2161 int replLen = replStr.length();
2162
2163 if (trgtLen > 0) {
2164 if (trgtLen == 1 && replLen == 1) {
2165 return replace(trgtStr.charAt(0), replStr.charAt(0));
2166 }
2167
2168 boolean thisIsLatin1 = this.isLatin1();
2169 boolean trgtIsLatin1 = trgtStr.isLatin1();
2170 boolean replIsLatin1 = replStr.isLatin1();
2171 String ret = (thisIsLatin1 && trgtIsLatin1 && replIsLatin1)
2172 ? StringLatin1.replace(value, thisLen,
2173 trgtStr.value, trgtLen,
2174 replStr.value, replLen)
2175 : StringUTF16.replace(value, thisLen, thisIsLatin1,
2176 trgtStr.value, trgtLen, trgtIsLatin1,
2177 replStr.value, replLen, replIsLatin1);
2178 if (ret != null) {
2179 return ret;
2180 }
2181 return this;
2182
2183 } else { // trgtLen == 0
2184 int resultLen;
2185 try {
2186 resultLen = Math.addExact(thisLen, Math.multiplyExact(
2187 Math.addExact(thisLen, 1), replLen));
2188 } catch (ArithmeticException ignored) {
2189 throw new OutOfMemoryError();
2190 }
2191
2192 StringBuilder sb = new StringBuilder(resultLen);
2193 sb.append(replStr);
2194 for (int i = 0; i < thisLen; ++i) {
2195 sb.append(charAt(i)).append(replStr);
2196 }
2197 return sb.toString();
2198 }
2199 }
2200
2201 /**
2202 * Splits this string around matches of the given
2203 * <a href="../util/regex/Pattern.html#sum">regular expression</a>.
2204 *
2205 * <p> The array returned by this method contains each substring of this
2206 * string that is terminated by another substring that matches the given
2207 * expression or is terminated by the end of the string. The substrings in
2208 * the array are in the order in which they occur in this string. If the
2209 * expression does not match any part of the input then the resulting array
2210 * has just one element, namely this string.
2211 *
2212 * <p> When there is a positive-width match at the beginning of this
2213 * string then an empty leading substring is included at the beginning
2214 * of the resulting array. A zero-width match at the beginning however
2215 * never produces such empty leading substring.
2216 *
2217 * <p> The {@code limit} parameter controls the number of times the
2218 * pattern is applied and therefore affects the length of the resulting
2219 * array.
2220 * <ul>
2221 * <li><p>
2222 * If the <i>limit</i> is positive then the pattern will be applied
2223 * at most <i>limit</i> - 1 times, the array's length will be
2224 * no greater than <i>limit</i>, and the array's last entry will contain
2225 * all input beyond the last matched delimiter.</p></li>
2226 *
2227 * <li><p>
2228 * If the <i>limit</i> is zero then the pattern will be applied as
2229 * many times as possible, the array can have any length, and trailing
2230 * empty strings will be discarded.</p></li>
2231 *
2232 * <li><p>
2233 * If the <i>limit</i> is negative then the pattern will be applied
2234 * as many times as possible and the array can have any length.</p></li>
2235 * </ul>
2236 *
2237 * <p> The string {@code "boo:and:foo"}, for example, yields the
2238 * following results with these parameters:
2239 *
2240 * <blockquote><table class="plain">
2241 * <caption style="display:none">Split example showing regex, limit, and result</caption>
2242 * <thead>
2243 * <tr>
2244 * <th scope="col">Regex</th>
2245 * <th scope="col">Limit</th>
2246 * <th scope="col">Result</th>
2247 * </tr>
2248 * </thead>
2249 * <tbody>
2250 * <tr><th scope="row" rowspan="3" style="font-weight:normal">:</th>
2251 * <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">2</th>
2252 * <td>{@code { "boo", "and:foo" }}</td></tr>
2253 * <tr><!-- : -->
2254 * <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">5</th>
2255 * <td>{@code { "boo", "and", "foo" }}</td></tr>
2256 * <tr><!-- : -->
2257 * <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">-2</th>
2258 * <td>{@code { "boo", "and", "foo" }}</td></tr>
2259 * <tr><th scope="row" rowspan="3" style="font-weight:normal">o</th>
2260 * <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">5</th>
2261 * <td>{@code { "b", "", ":and:f", "", "" }}</td></tr>
2262 * <tr><!-- o -->
2263 * <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">-2</th>
2264 * <td>{@code { "b", "", ":and:f", "", "" }}</td></tr>
2265 * <tr><!-- o -->
2266 * <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">0</th>
2267 * <td>{@code { "b", "", ":and:f" }}</td></tr>
2268 * </tbody>
2269 * </table></blockquote>
2270 *
2271 * <p> An invocation of this method of the form
2272 * <i>str.</i>{@code split(}<i>regex</i>{@code ,} <i>n</i>{@code )}
2273 * yields the same result as the expression
2274 *
2275 * <blockquote>
2276 * <code>
2277 * {@link java.util.regex.Pattern}.{@link
2278 * java.util.regex.Pattern#compile compile}(<i>regex</i>).{@link
2279 * java.util.regex.Pattern#split(java.lang.CharSequence,int) split}(<i>str</i>, <i>n</i>)
2280 * </code>
2281 * </blockquote>
2282 *
2283 *
2284 * @param regex
2285 * the delimiting regular expression
2286 *
2287 * @param limit
2288 * the result threshold, as described above
2289 *
2290 * @return the array of strings computed by splitting this string
2291 * around matches of the given regular expression
2292 *
2293 * @throws PatternSyntaxException
2294 * if the regular expression's syntax is invalid
2295 *
2296 * @see java.util.regex.Pattern
2297 *
2298 * @since 1.4
2299 * @spec JSR-51
2300 */
2301 public String[] split(String regex, int limit) {
2302 /* fastpath if the regex is a
2303 (1)one-char String and this character is not one of the
2304 RegEx's meta characters ".$|()[{^?*+\\", or
2305 (2)two-char String and the first char is the backslash and
2306 the second is not the ascii digit or ascii letter.
2307 */
2308 char ch = 0;
2309 if (((regex.length() == 1 &&
2310 ".$|()[{^?*+\\".indexOf(ch = regex.charAt(0)) == -1) ||
2311 (regex.length() == 2 &&
2312 regex.charAt(0) == '\\' &&
2313 (((ch = regex.charAt(1))-'0')|('9'-ch)) < 0 &&
2314 ((ch-'a')|('z'-ch)) < 0 &&
2315 ((ch-'A')|('Z'-ch)) < 0)) &&
2316 (ch < Character.MIN_HIGH_SURROGATE ||
2317 ch > Character.MAX_LOW_SURROGATE))
2318 {
2319 int off = 0;
2320 int next = 0;
2321 boolean limited = limit > 0;
2322 ArrayList<String> list = new ArrayList<>();
2323 while ((next = indexOf(ch, off)) != -1) {
2324 if (!limited || list.size() < limit - 1) {
2325 list.add(substring(off, next));
2326 off = next + 1;
2327 } else { // last one
2328 //assert (list.size() == limit - 1);
2329 int last = length();
2330 list.add(substring(off, last));
2331 off = last;
2332 break;
2333 }
2334 }
2335 // If no match was found, return this
2336 if (off == 0)
2337 return new String[]{this};
2338
2339 // Add remaining segment
2340 if (!limited || list.size() < limit)
2341 list.add(substring(off, length()));
2342
2343 // Construct result
2344 int resultSize = list.size();
2345 if (limit == 0) {
2346 while (resultSize > 0 && list.get(resultSize - 1).isEmpty()) {
2347 resultSize--;
2348 }
2349 }
2350 String[] result = new String[resultSize];
2351 return list.subList(0, resultSize).toArray(result);
2352 }
2353 return Pattern.compile(regex).split(this, limit);
2354 }
2355
2356 /**
2357 * Splits this string around matches of the given <a
2358 * href="../util/regex/Pattern.html#sum">regular expression</a>.
2359 *
2360 * <p> This method works as if by invoking the two-argument {@link
2361 * #split(String, int) split} method with the given expression and a limit
2362 * argument of zero. Trailing empty strings are therefore not included in
2363 * the resulting array.
2364 *
2365 * <p> The string {@code "boo:and:foo"}, for example, yields the following
2366 * results with these expressions:
2367 *
2368 * <blockquote><table class="plain">
2369 * <caption style="display:none">Split examples showing regex and result</caption>
2370 * <thead>
2371 * <tr>
2372 * <th scope="col">Regex</th>
2373 * <th scope="col">Result</th>
2374 * </tr>
2375 * </thead>
2376 * <tbody>
2377 * <tr><th scope="row" style="text-weight:normal">:</th>
2378 * <td>{@code { "boo", "and", "foo" }}</td></tr>
2379 * <tr><th scope="row" style="text-weight:normal">o</th>
2380 * <td>{@code { "b", "", ":and:f" }}</td></tr>
2381 * </tbody>
2382 * </table></blockquote>
2383 *
2384 *
2385 * @param regex
2386 * the delimiting regular expression
2387 *
2388 * @return the array of strings computed by splitting this string
2389 * around matches of the given regular expression
2390 *
2391 * @throws PatternSyntaxException
2392 * if the regular expression's syntax is invalid
2393 *
2394 * @see java.util.regex.Pattern
2395 *
2396 * @since 1.4
2397 * @spec JSR-51
2398 */
2399 public String[] split(String regex) {
2400 return split(regex, 0);
2401 }
2402
2403 /**
2404 * Returns a new String composed of copies of the
2405 * {@code CharSequence elements} joined together with a copy of
2406 * the specified {@code delimiter}.
2407 *
2408 * <blockquote>For example,
2409 * <pre>{@code
2410 * String message = String.join("-", "Java", "is", "cool");
2411 * // message returned is: "Java-is-cool"
2412 * }</pre></blockquote>
2413 *
2414 * Note that if an element is null, then {@code "null"} is added.
2415 *
2416 * @param delimiter the delimiter that separates each element
2417 * @param elements the elements to join together.
2418 *
2419 * @return a new {@code String} that is composed of the {@code elements}
2420 * separated by the {@code delimiter}
2421 *
2422 * @throws NullPointerException If {@code delimiter} or {@code elements}
2423 * is {@code null}
2424 *
2425 * @see java.util.StringJoiner
2426 * @since 1.8
2427 */
2428 public static String join(CharSequence delimiter, CharSequence... elements) {
2429 Objects.requireNonNull(delimiter);
2430 Objects.requireNonNull(elements);
2431 // Number of elements not likely worth Arrays.stream overhead.
2432 StringJoiner joiner = new StringJoiner(delimiter);
2433 for (CharSequence cs: elements) {
2434 joiner.add(cs);
2435 }
2436 return joiner.toString();
2437 }
2438
2439 /**
2440 * Returns a new {@code String} composed of copies of the
2441 * {@code CharSequence elements} joined together with a copy of the
2442 * specified {@code delimiter}.
2443 *
2444 * <blockquote>For example,
2445 * <pre>{@code
2446 * List<String> strings = List.of("Java", "is", "cool");
2447 * String message = String.join(" ", strings);
2448 * // message returned is: "Java is cool"
2449 *
2450 * Set<String> strings =
2451 * new LinkedHashSet<>(List.of("Java", "is", "very", "cool"));
2452 * String message = String.join("-", strings);
2453 * // message returned is: "Java-is-very-cool"
2454 * }</pre></blockquote>
2455 *
2456 * Note that if an individual element is {@code null}, then {@code "null"} is added.
2457 *
2458 * @param delimiter a sequence of characters that is used to separate each
2459 * of the {@code elements} in the resulting {@code String}
2460 * @param elements an {@code Iterable} that will have its {@code elements}
2461 * joined together.
2462 *
2463 * @return a new {@code String} that is composed from the {@code elements}
2464 * argument
2465 *
2466 * @throws NullPointerException If {@code delimiter} or {@code elements}
2467 * is {@code null}
2468 *
2469 * @see #join(CharSequence,CharSequence...)
2470 * @see java.util.StringJoiner
2471 * @since 1.8
2472 */
2473 public static String join(CharSequence delimiter,
2474 Iterable<? extends CharSequence> elements) {
2475 Objects.requireNonNull(delimiter);
2476 Objects.requireNonNull(elements);
2477 StringJoiner joiner = new StringJoiner(delimiter);
2478 for (CharSequence cs: elements) {
2479 joiner.add(cs);
2480 }
2481 return joiner.toString();
2482 }
2483
2484 /**
2485 * Converts all of the characters in this {@code String} to lower
2486 * case using the rules of the given {@code Locale}. Case mapping is based
2487 * on the Unicode Standard version specified by the {@link java.lang.Character Character}
2488 * class. Since case mappings are not always 1:1 char mappings, the resulting
2489 * {@code String} may be a different length than the original {@code String}.
2490 * <p>
2491 * Examples of lowercase mappings are in the following table:
2492 * <table class="plain">
2493 * <caption style="display:none">Lowercase mapping examples showing language code of locale, upper case, lower case, and description</caption>
2494 * <thead>
2495 * <tr>
2496 * <th scope="col">Language Code of Locale</th>
2497 * <th scope="col">Upper Case</th>
2498 * <th scope="col">Lower Case</th>
2499 * <th scope="col">Description</th>
2500 * </tr>
2501 * </thead>
2502 * <tbody>
2503 * <tr>
2504 * <td>tr (Turkish)</td>
2505 * <th scope="row" style="font-weight:normal; text-align:left">\u0130</th>
2506 * <td>\u0069</td>
2507 * <td>capital letter I with dot above -> small letter i</td>
2508 * </tr>
2509 * <tr>
2510 * <td>tr (Turkish)</td>
2511 * <th scope="row" style="font-weight:normal; text-align:left">\u0049</th>
2512 * <td>\u0131</td>
2513 * <td>capital letter I -> small letter dotless i </td>
2514 * </tr>
2515 * <tr>
2516 * <td>(all)</td>
2517 * <th scope="row" style="font-weight:normal; text-align:left">French Fries</th>
2518 * <td>french fries</td>
2519 * <td>lowercased all chars in String</td>
2520 * </tr>
2521 * <tr>
2522 * <td>(all)</td>
2523 * <th scope="row" style="font-weight:normal; text-align:left">
2524 * ΙΧΘΥΣ</th>
2525 * <td>ιχθυσ</td>
2526 * <td>lowercased all chars in String</td>
2527 * </tr>
2528 * </tbody>
2529 * </table>
2530 *
2531 * @param locale use the case transformation rules for this locale
2532 * @return the {@code String}, converted to lowercase.
2533 * @see java.lang.String#toLowerCase()
2534 * @see java.lang.String#toUpperCase()
2535 * @see java.lang.String#toUpperCase(Locale)
2536 * @since 1.1
2537 */
2538 public String toLowerCase(Locale locale) {
2539 return isLatin1() ? StringLatin1.toLowerCase(this, value, locale)
2540 : StringUTF16.toLowerCase(this, value, locale);
2541 }
2542
2543 /**
2544 * Converts all of the characters in this {@code String} to lower
2545 * case using the rules of the default locale. This is equivalent to calling
2546 * {@code toLowerCase(Locale.getDefault())}.
2547 * <p>
2548 * <b>Note:</b> This method is locale sensitive, and may produce unexpected
2549 * results if used for strings that are intended to be interpreted locale
2550 * independently.
2551 * Examples are programming language identifiers, protocol keys, and HTML
2552 * tags.
2553 * For instance, {@code "TITLE".toLowerCase()} in a Turkish locale
2554 * returns {@code "t\u005Cu0131tle"}, where '\u005Cu0131' is the
2555 * LATIN SMALL LETTER DOTLESS I character.
2556 * To obtain correct results for locale insensitive strings, use
2557 * {@code toLowerCase(Locale.ROOT)}.
2558 *
2559 * @return the {@code String}, converted to lowercase.
2560 * @see java.lang.String#toLowerCase(Locale)
2561 */
2562 public String toLowerCase() {
2563 return toLowerCase(Locale.getDefault());
2564 }
2565
2566 /**
2567 * Converts all of the characters in this {@code String} to upper
2568 * case using the rules of the given {@code Locale}. Case mapping is based
2569 * on the Unicode Standard version specified by the {@link java.lang.Character Character}
2570 * class. Since case mappings are not always 1:1 char mappings, the resulting
2571 * {@code String} may be a different length than the original {@code String}.
2572 * <p>
2573 * Examples of locale-sensitive and 1:M case mappings are in the following table.
2574 *
2575 * <table class="plain">
2576 * <caption style="display:none">Examples of locale-sensitive and 1:M case mappings. Shows Language code of locale, lower case, upper case, and description.</caption>
2577 * <thead>
2578 * <tr>
2579 * <th scope="col">Language Code of Locale</th>
2580 * <th scope="col">Lower Case</th>
2581 * <th scope="col">Upper Case</th>
2582 * <th scope="col">Description</th>
2583 * </tr>
2584 * </thead>
2585 * <tbody>
2586 * <tr>
2587 * <td>tr (Turkish)</td>
2588 * <th scope="row" style="font-weight:normal; text-align:left">\u0069</th>
2589 * <td>\u0130</td>
2590 * <td>small letter i -> capital letter I with dot above</td>
2591 * </tr>
2592 * <tr>
2593 * <td>tr (Turkish)</td>
2594 * <th scope="row" style="font-weight:normal; text-align:left">\u0131</th>
2595 * <td>\u0049</td>
2596 * <td>small letter dotless i -> capital letter I</td>
2597 * </tr>
2598 * <tr>
2599 * <td>(all)</td>
2600 * <th scope="row" style="font-weight:normal; text-align:left">\u00df</th>
2601 * <td>\u0053 \u0053</td>
2602 * <td>small letter sharp s -> two letters: SS</td>
2603 * </tr>
2604 * <tr>
2605 * <td>(all)</td>
2606 * <th scope="row" style="font-weight:normal; text-align:left">Fahrvergnügen</th>
2607 * <td>FAHRVERGNÜGEN</td>
2608 * <td></td>
2609 * </tr>
2610 * </tbody>
2611 * </table>
2612 * @param locale use the case transformation rules for this locale
2613 * @return the {@code String}, converted to uppercase.
2614 * @see java.lang.String#toUpperCase()
2615 * @see java.lang.String#toLowerCase()
2616 * @see java.lang.String#toLowerCase(Locale)
2617 * @since 1.1
2618 */
2619 public String toUpperCase(Locale locale) {
2620 return isLatin1() ? StringLatin1.toUpperCase(this, value, locale)
2621 : StringUTF16.toUpperCase(this, value, locale);
2622 }
2623
2624 /**
2625 * Converts all of the characters in this {@code String} to upper
2626 * case using the rules of the default locale. This method is equivalent to
2627 * {@code toUpperCase(Locale.getDefault())}.
2628 * <p>
2629 * <b>Note:</b> This method is locale sensitive, and may produce unexpected
2630 * results if used for strings that are intended to be interpreted locale
2631 * independently.
2632 * Examples are programming language identifiers, protocol keys, and HTML
2633 * tags.
2634 * For instance, {@code "title".toUpperCase()} in a Turkish locale
2635 * returns {@code "T\u005Cu0130TLE"}, where '\u005Cu0130' is the
2636 * LATIN CAPITAL LETTER I WITH DOT ABOVE character.
2637 * To obtain correct results for locale insensitive strings, use
2638 * {@code toUpperCase(Locale.ROOT)}.
2639 *
2640 * @return the {@code String}, converted to uppercase.
2641 * @see java.lang.String#toUpperCase(Locale)
2642 */
2643 public String toUpperCase() {
2644 return toUpperCase(Locale.getDefault());
2645 }
2646
2647 /**
2648 * Returns a string whose value is this string, with all leading
2649 * and trailing space removed, where space is defined
2650 * as any character whose codepoint is less than or equal to
2651 * {@code 'U+0020'} (the space character).
2652 * <p>
2653 * If this {@code String} object represents an empty character
2654 * sequence, or the first and last characters of character sequence
2655 * represented by this {@code String} object both have codes
2656 * that are not space (as defined above), then a
2657 * reference to this {@code String} object is returned.
2658 * <p>
2659 * Otherwise, if all characters in this string are space (as
2660 * defined above), then a {@code String} object representing an
2661 * empty string is returned.
2662 * <p>
2663 * Otherwise, let <i>k</i> be the index of the first character in the
2664 * string whose code is not a space (as defined above) and let
2665 * <i>m</i> be the index of the last character in the string whose code
2666 * is not a space (as defined above). A {@code String}
2667 * object is returned, representing the substring of this string that
2668 * begins with the character at index <i>k</i> and ends with the
2669 * character at index <i>m</i>-that is, the result of
2670 * {@code this.substring(k, m + 1)}.
2671 * <p>
2672 * This method may be used to trim space (as defined above) from
2673 * the beginning and end of a string.
2674 *
2675 * @return a string whose value is this string, with all leading
2676 * and trailing space removed, or this string if it
2677 * has no leading or trailing space.
2678 */
2679 public String trim() {
2680 String ret = isLatin1() ? StringLatin1.trim(value)
2681 : StringUTF16.trim(value);
2682 return ret == null ? this : ret;
2683 }
2684
2685 /**
2686 * Returns a string whose value is this string, with all leading
2687 * and trailing {@linkplain Character#isWhitespace(int) white space}
2688 * removed.
2689 * <p>
2690 * If this {@code String} object represents an empty string,
2691 * or if all code points in this string are
2692 * {@linkplain Character#isWhitespace(int) white space}, then an empty string
2693 * is returned.
2694 * <p>
2695 * Otherwise, returns a substring of this string beginning with the first
2696 * code point that is not a {@linkplain Character#isWhitespace(int) white space}
2697 * up to and including the last code point that is not a
2698 * {@linkplain Character#isWhitespace(int) white space}.
2699 * <p>
2700 * This method may be used to strip
2701 * {@linkplain Character#isWhitespace(int) white space} from
2702 * the beginning and end of a string.
2703 *
2704 * @return a string whose value is this string, with all leading
2705 * and trailing white space removed
2706 *
2707 * @see Character#isWhitespace(int)
2708 *
2709 * @since 11
2710 */
2711 public String strip() {
2712 String ret = isLatin1() ? StringLatin1.strip(value)
2713 : StringUTF16.strip(value);
2714 return ret == null ? this : ret;
2715 }
2716
2717 /**
2718 * Returns a string whose value is this string, with all leading
2719 * {@linkplain Character#isWhitespace(int) white space} removed.
2720 * <p>
2721 * If this {@code String} object represents an empty string,
2722 * or if all code points in this string are
2723 * {@linkplain Character#isWhitespace(int) white space}, then an empty string
2724 * is returned.
2725 * <p>
2726 * Otherwise, returns a substring of this string beginning with the first
2727 * code point that is not a {@linkplain Character#isWhitespace(int) white space}
2728 * up to and including the last code point of this string.
2729 * <p>
2730 * This method may be used to trim
2731 * {@linkplain Character#isWhitespace(int) white space} from
2732 * the beginning of a string.
2733 *
2734 * @return a string whose value is this string, with all leading white
2735 * space removed
2736 *
2737 * @see Character#isWhitespace(int)
2738 *
2739 * @since 11
2740 */
2741 public String stripLeading() {
2742 String ret = isLatin1() ? StringLatin1.stripLeading(value)
2743 : StringUTF16.stripLeading(value);
2744 return ret == null ? this : ret;
2745 }
2746
2747 /**
2748 * Returns a string whose value is this string, with all trailing
2749 * {@linkplain Character#isWhitespace(int) white space} removed.
2750 * <p>
2751 * If this {@code String} object represents an empty string,
2752 * or if all characters in this string are
2753 * {@linkplain Character#isWhitespace(int) white space}, then an empty string
2754 * is returned.
2755 * <p>
2756 * Otherwise, returns a substring of this string beginning with the first
2757 * code point of this string up to and including the last code point
2758 * that is not a {@linkplain Character#isWhitespace(int) white space}.
2759 * <p>
2760 * This method may be used to trim
2761 * {@linkplain Character#isWhitespace(int) white space} from
2762 * the end of a string.
2763 *
2764 * @return a string whose value is this string, with all trailing white
2765 * space removed
2766 *
2767 * @see Character#isWhitespace(int)
2768 *
2769 * @since 11
2770 */
2771 public String stripTrailing() {
2772 String ret = isLatin1() ? StringLatin1.stripTrailing(value)
2773 : StringUTF16.stripTrailing(value);
2774 return ret == null ? this : ret;
2775 }
2776
2777 /**
2778 * Returns {@code true} if the string is empty or contains only
2779 * {@linkplain Character#isWhitespace(int) white space} codepoints,
2780 * otherwise {@code false}.
2781 *
2782 * @return {@code true} if the string is empty or contains only
2783 * {@linkplain Character#isWhitespace(int) white space} codepoints,
2784 * otherwise {@code false}
2785 *
2786 * @see Character#isWhitespace(int)
2787 *
2788 * @since 11
2789 */
2790 public boolean isBlank() {
2791 return indexOfNonWhitespace() == length();
2792 }
2793
2794 /**
2795 * Returns a stream of lines extracted from this string,
2796 * separated by line terminators.
2797 * <p>
2798 * A <i>line terminator</i> is one of the following:
2799 * a line feed character {@code "\n"} (U+000A),
2800 * a carriage return character {@code "\r"} (U+000D),
2801 * or a carriage return followed immediately by a line feed
2802 * {@code "\r\n"} (U+000D U+000A).
2803 * <p>
2804 * A <i>line</i> is either a sequence of zero or more characters
2805 * followed by a line terminator, or it is a sequence of one or
2806 * more characters followed by the end of the string. A
2807 * line does not include the line terminator.
2808 * <p>
2809 * The stream returned by this method contains the lines from
2810 * this string in the order in which they occur.
2811 *
2812 * @apiNote This definition of <i>line</i> implies that an empty
2813 * string has zero lines and that there is no empty line
2814 * following a line terminator at the end of a string.
2815 *
2816 * @implNote This method provides better performance than
2817 * split("\R") by supplying elements lazily and
2818 * by faster search of new line terminators.
2819 *
2820 * @return the stream of lines extracted from this string
2821 *
2822 * @since 11
2823 */
2824 public Stream<String> lines() {
2825 return isLatin1() ? StringLatin1.lines(value) : StringUTF16.lines(value);
2826 }
2827
2828 /**
2829 * Adjusts the indentation of each line of this string based on the value of
2830 * {@code n}, and normalizes line termination characters.
2831 * <p>
2832 * This string is conceptually separated into lines using
2833 * {@link String#lines()}. Each line is then adjusted as described below
2834 * and then suffixed with a line feed {@code "\n"} (U+000A). The resulting
2835 * lines are then concatenated and returned.
2836 * <p>
2837 * If {@code n > 0} then {@code n} spaces (U+0020) are inserted at the
2838 * beginning of each line.
2839 * <p>
2840 * If {@code n < 0} then up to {@code n}
2841 * {@linkplain Character#isWhitespace(int) white space characters} are removed
2842 * from the beginning of each line. If a given line does not contain
2843 * sufficient white space then all leading
2844 * {@linkplain Character#isWhitespace(int) white space characters} are removed.
2845 * Each white space character is treated as a single character. In
2846 * particular, the tab character {@code "\t"} (U+0009) is considered a
2847 * single character; it is not expanded.
2848 * <p>
2849 * If {@code n == 0} then the line remains unchanged. However, line
2850 * terminators are still normalized.
2851 *
2852 * @param n number of leading
2853 * {@linkplain Character#isWhitespace(int) white space characters}
2854 * to add or remove
2855 *
2856 * @return string with indentation adjusted and line endings normalized
2857 *
2858 * @see String#lines()
2859 * @see String#isBlank()
2860 * @see Character#isWhitespace(int)
2861 *
2862 * @since 12
2863 */
2864 public String indent(int n) {
2865 if (isEmpty()) {
2866 return "";
2867 }
2868 Stream<String> stream = lines();
2869 if (n > 0) {
2870 final String spaces = " ".repeat(n);
2871 stream = stream.map(s -> spaces + s);
2872 } else if (n == Integer.MIN_VALUE) {
2873 stream = stream.map(s -> s.stripLeading());
2874 } else if (n < 0) {
2875 stream = stream.map(s -> s.substring(Math.min(-n, s.indexOfNonWhitespace())));
2876 }
2877 return stream.collect(Collectors.joining("\n", "", "\n"));
2878 }
2879
2880 private int indexOfNonWhitespace() {
2881 return isLatin1() ? StringLatin1.indexOfNonWhitespace(value)
2882 : StringUTF16.indexOfNonWhitespace(value);
2883 }
2884
2885 private int lastIndexOfNonWhitespace() {
2886 return isLatin1() ? StringLatin1.lastIndexOfNonWhitespace(value)
2887 : StringUTF16.lastIndexOfNonWhitespace(value);
2888 }
2889
2890 /**
2891 * {@preview Associated with text blocks, a preview feature of
2892 * the Java language.
2893 *
2894 * This method is associated with <i>text blocks</i>, a preview
2895 * feature of the Java language. Programs can only use this
2896 * method when preview features are enabled. Preview features
2897 * may be removed in a future release, or upgraded to permanent
2898 * features of the Java language.}
2899 *
2900 * Returns a string whose value is this string, with incidental
2901 * {@linkplain Character#isWhitespace(int) white space} removed from
2902 * the beginning and end of every line.
2903 * <p>
2904 * Incidental {@linkplain Character#isWhitespace(int) white space}
2905 * is often present in a text block to align the content with the opening
2906 * delimiter. For example, in the following code, dots represent incidental
2907 * {@linkplain Character#isWhitespace(int) white space}:
2908 * <blockquote><pre>
2909 * String html = """
2910 * ..............<html>
2911 * .............. <body>
2912 * .............. <p>Hello, world</p>
2913 * .............. </body>
2914 * ..............</html>
2915 * ..............""";
2916 * </pre></blockquote>
2917 * This method treats the incidental
2918 * {@linkplain Character#isWhitespace(int) white space} as indentation to be
2919 * stripped, producing a string that preserves the relative indentation of
2920 * the content. Using | to visualize the start of each line of the string:
2921 * <blockquote><pre>
2922 * |<html>
2923 * | <body>
2924 * | <p>Hello, world</p>
2925 * | </body>
2926 * |</html>
2927 * </pre></blockquote>
2928 * First, the individual lines of this string are extracted as if by using
2929 * {@link String#lines()}.
2930 * <p>
2931 * Then, the <i>minimum indentation</i> (min) is determined as follows.
2932 * For each non-blank line (as defined by {@link String#isBlank()}), the
2933 * leading {@linkplain Character#isWhitespace(int) white space} characters are
2934 * counted. The leading {@linkplain Character#isWhitespace(int) white space}
2935 * characters on the last line are also counted even if
2936 * {@linkplain String#isBlank() blank}. The <i>min</i> value is the smallest
2937 * of these counts.
2938 * <p>
2939 * For each {@linkplain String#isBlank() non-blank} line, <i>min</i> leading
2940 * {@linkplain Character#isWhitespace(int) white space} characters are removed,
2941 * and any trailing {@linkplain Character#isWhitespace(int) white space}
2942 * characters are removed. {@linkplain String#isBlank() Blank} lines are
2943 * replaced with the empty string.
2944 *
2945 * <p>
2946 * Finally, the lines are joined into a new string, using the LF character
2947 * {@code "\n"} (U+000A) to separate lines.
2948 *
2949 * @apiNote
2950 * This method's primary purpose is to shift a block of lines as far as
2951 * possible to the left, while preserving relative indentation. Lines
2952 * that were indented the least will thus have no leading
2953 * {@linkplain Character#isWhitespace(int) white space}.
2954 * The line count of the result will be the same as line count of this
2955 * string.
2956 * If this string ends with a line terminator then the result will end
2957 * with a line terminator.
2958 *
2959 * @implNote
2960 * This method treats all {@linkplain Character#isWhitespace(int) white space}
2961 * characters as having equal width. As long as the indentation on every
2962 * line is consistently composed of the same character sequences, then the
2963 * result will be as described above.
2964 *
2965 * @return string with incidental indentation removed and line
2966 * terminators normalized
2967 *
2968 * @see String#lines()
2969 * @see String#isBlank()
2970 * @see String#indent(int)
2971 * @see Character#isWhitespace(int)
2972 *
2973 * @since 13
2974 *
2975 */
2976 @jdk.internal.PreviewFeature(feature=jdk.internal.PreviewFeature.Feature.TEXT_BLOCKS,
2977 essentialAPI=true)
2978 public String stripIndent() {
2979 int length = length();
2980 if (length == 0) {
2981 return "";
2982 }
2983 char lastChar = charAt(length - 1);
2984 boolean optOut = lastChar == '\n' || lastChar == '\r';
2985 List<String> lines = lines().collect(Collectors.toList());
2986 final int outdent = optOut ? 0 : outdent(lines);
2987 return lines.stream()
2988 .map(line -> {
2989 int firstNonWhitespace = line.indexOfNonWhitespace();
2990 int lastNonWhitespace = line.lastIndexOfNonWhitespace();
2991 int incidentalWhitespace = Math.min(outdent, firstNonWhitespace);
2992 return firstNonWhitespace > lastNonWhitespace
2993 ? "" : line.substring(incidentalWhitespace, lastNonWhitespace);
2994 })
2995 .collect(Collectors.joining("\n", "", optOut ? "\n" : ""));
2996 }
2997
2998 private static int outdent(List<String> lines) {
2999 // Note: outdent is guaranteed to be zero or positive number.
3000 // If there isn't a non-blank line then the last must be blank
3001 int outdent = Integer.MAX_VALUE;
3002 for (String line : lines) {
3003 int leadingWhitespace = line.indexOfNonWhitespace();
3004 if (leadingWhitespace != line.length()) {
3005 outdent = Integer.min(outdent, leadingWhitespace);
3006 }
3007 }
3008 String lastLine = lines.get(lines.size() - 1);
3009 if (lastLine.isBlank()) {
3010 outdent = Integer.min(outdent, lastLine.length());
3011 }
3012 return outdent;
3013 }
3014
3015 /**
3016 * {@preview Associated with text blocks, a preview feature of
3017 * the Java language.
3018 *
3019 * This method is associated with <i>text blocks</i>, a preview
3020 * feature of the Java language. Programs can only use this
3021 * method when preview features are enabled. Preview features
3022 * may be removed in a future release, or upgraded to permanent
3023 * features of the Java language.}
3024 *
3025 * Returns a string whose value is this string, with escape sequences
3026 * translated as if in a string literal.
3027 * <p>
3028 * Escape sequences are translated as follows;
3029 * <table class="striped">
3030 * <caption style="display:none">Translation</caption>
3031 * <thead>
3032 * <tr>
3033 * <th scope="col">Escape</th>
3034 * <th scope="col">Name</th>
3035 * <th scope="col">Translation</th>
3036 * </tr>
3037 * </thead>
3038 * <tbody>
3039 * <tr>
3040 * <th scope="row">{@code \u005Cb}</th>
3041 * <td>backspace</td>
3042 * <td>{@code U+0008}</td>
3043 * </tr>
3044 * <tr>
3045 * <th scope="row">{@code \u005Ct}</th>
3046 * <td>horizontal tab</td>
3047 * <td>{@code U+0009}</td>
3048 * </tr>
3049 * <tr>
3050 * <th scope="row">{@code \u005Cn}</th>
3051 * <td>line feed</td>
3052 * <td>{@code U+000A}</td>
3053 * </tr>
3054 * <tr>
3055 * <th scope="row">{@code \u005Cf}</th>
3056 * <td>form feed</td>
3057 * <td>{@code U+000C}</td>
3058 * </tr>
3059 * <tr>
3060 * <th scope="row">{@code \u005Cr}</th>
3061 * <td>carriage return</td>
3062 * <td>{@code U+000D}</td>
3063 * </tr>
3064 * <tr>
3065 * <th scope="row">{@code \u005Cs}</th>
3066 * <td>space</td>
3067 * <td>{@code U+0020}</td>
3068 * </tr>
3069 * <tr>
3070 * <th scope="row">{@code \u005C"}</th>
3071 * <td>double quote</td>
3072 * <td>{@code U+0022}</td>
3073 * </tr>
3074 * <tr>
3075 * <th scope="row">{@code \u005C'}</th>
3076 * <td>single quote</td>
3077 * <td>{@code U+0027}</td>
3078 * </tr>
3079 * <tr>
3080 * <th scope="row">{@code \u005C\u005C}</th>
3081 * <td>backslash</td>
3082 * <td>{@code U+005C}</td>
3083 * </tr>
3084 * <tr>
3085 * <th scope="row">{@code \u005C0 - \u005C377}</th>
3086 * <td>octal escape</td>
3087 * <td>code point equivalents</td>
3088 * </tr>
3089 * <tr>
3090 * <th scope="row">{@code \u005C<line-terminator>}</th>
3091 * <td>continuation</td>
3092 * <td>discard</td>
3093 * </tr>
3094 * </tbody>
3095 * </table>
3096 *
3097 * @implNote
3098 * This method does <em>not</em> translate Unicode escapes such as "{@code \u005cu2022}".
3099 * Unicode escapes are translated by the Java compiler when reading input characters and
3100 * are not part of the string literal specification.
3101 *
3102 * @throws IllegalArgumentException when an escape sequence is malformed.
3103 *
3104 * @return String with escape sequences translated.
3105 *
3106 * @jls 3.10.7 Escape Sequences
3107 *
3108 * @since 13
3109 */
3110 @jdk.internal.PreviewFeature(feature=jdk.internal.PreviewFeature.Feature.TEXT_BLOCKS,
3111 essentialAPI=true)
3112 public String translateEscapes() {
3113 if (isEmpty()) {
3114 return "";
3115 }
3116 char[] chars = toCharArray();
3117 int length = chars.length;
3118 int from = 0;
3119 int to = 0;
3120 while (from < length) {
3121 char ch = chars[from++];
3122 if (ch == '\\') {
3123 ch = from < length ? chars[from++] : '\0';
3124 switch (ch) {
3125 case 'b':
3126 ch = '\b';
3127 break;
3128 case 'f':
3129 ch = '\f';
3130 break;
3131 case 'n':
3132 ch = '\n';
3133 break;
3134 case 'r':
3135 ch = '\r';
3136 break;
3137 case 's':
3138 ch = ' ';
3139 break;
3140 case 't':
3141 ch = '\t';
3142 break;
3143 case '\'':
3144 case '\"':
3145 case '\\':
3146 // as is
3147 break;
3148 case '0': case '1': case '2': case '3':
3149 case '4': case '5': case '6': case '7':
3150 int limit = Integer.min(from + (ch <= '3' ? 2 : 1), length);
3151 int code = ch - '0';
3152 while (from < limit) {
3153 ch = chars[from];
3154 if (ch < '0' || '7' < ch) {
3155 break;
3156 }
3157 from++;
3158 code = (code << 3) | (ch - '0');
3159 }
3160 ch = (char)code;
3161 break;
3162 case '\n':
3163 continue;
3164 case '\r':
3165 if (from < length && chars[from] == '\n') {
3166 from++;
3167 }
3168 continue;
3169 default: {
3170 String msg = String.format(
3171 "Invalid escape sequence: \\%c \\\\u%04X",
3172 ch, (int)ch);
3173 throw new IllegalArgumentException(msg);
3174 }
3175 }
3176 }
3177
3178 chars[to++] = ch;
3179 }
3180
3181 return new String(chars, 0, to);
3182 }
3183
3184 /**
3185 * This method allows the application of a function to {@code this}
3186 * string. The function should expect a single String argument
3187 * and produce an {@code R} result.
3188 * <p>
3189 * Any exception thrown by {@code f()} will be propagated to the
3190 * caller.
3191 *
3192 * @param f functional interface to a apply
3193 *
3194 * @param <R> class of the result
3195 *
3196 * @return the result of applying the function to this string
3197 *
3198 * @see java.util.function.Function
3199 *
3200 * @since 12
3201 */
3202 public <R> R transform(Function<? super String, ? extends R> f) {
3203 return f.apply(this);
3204 }
3205
3206 /**
3207 * This object (which is already a string!) is itself returned.
3208 *
3209 * @return the string itself.
3210 */
3211 public String toString() {
3212 return this;
3213 }
3214
3215 /**
3216 * Returns a stream of {@code int} zero-extending the {@code char} values
3217 * from this sequence. Any char which maps to a <a
3218 * href="{@docRoot}/java.base/java/lang/Character.html#unicode">surrogate code
3219 * point</a> is passed through uninterpreted.
3220 *
3221 * @return an IntStream of char values from this sequence
3222 * @since 9
3223 */
3224 @Override
3225 public IntStream chars() {
3226 return StreamSupport.intStream(
3227 isLatin1() ? new StringLatin1.CharsSpliterator(value, Spliterator.IMMUTABLE)
3228 : new StringUTF16.CharsSpliterator(value, Spliterator.IMMUTABLE),
3229 false);
3230 }
3231
3232
3233 /**
3234 * Returns a stream of code point values from this sequence. Any surrogate
3235 * pairs encountered in the sequence are combined as if by {@linkplain
3236 * Character#toCodePoint Character.toCodePoint} and the result is passed
3237 * to the stream. Any other code units, including ordinary BMP characters,
3238 * unpaired surrogates, and undefined code units, are zero-extended to
3239 * {@code int} values which are then passed to the stream.
3240 *
3241 * @return an IntStream of Unicode code points from this sequence
3242 * @since 9
3243 */
3244 @Override
3245 public IntStream codePoints() {
3246 return StreamSupport.intStream(
3247 isLatin1() ? new StringLatin1.CharsSpliterator(value, Spliterator.IMMUTABLE)
3248 : new StringUTF16.CodePointsSpliterator(value, Spliterator.IMMUTABLE),
3249 false);
3250 }
3251
3252 /**
3253 * Converts this string to a new character array.
3254 *
3255 * @return a newly allocated character array whose length is the length
3256 * of this string and whose contents are initialized to contain
3257 * the character sequence represented by this string.
3258 */
3259 public char[] toCharArray() {
3260 return isLatin1() ? StringLatin1.toChars(value)
3261 : StringUTF16.toChars(value);
3262 }
3263
3264 /**
3265 * Returns a formatted string using the specified format string and
3266 * arguments.
3267 *
3268 * <p> The locale always used is the one returned by {@link
3269 * java.util.Locale#getDefault(java.util.Locale.Category)
3270 * Locale.getDefault(Locale.Category)} with
3271 * {@link java.util.Locale.Category#FORMAT FORMAT} category specified.
3272 *
3273 * @param format
3274 * A <a href="../util/Formatter.html#syntax">format string</a>
3275 *
3276 * @param args
3277 * Arguments referenced by the format specifiers in the format
3278 * string. If there are more arguments than format specifiers, the
3279 * extra arguments are ignored. The number of arguments is
3280 * variable and may be zero. The maximum number of arguments is
3281 * limited by the maximum dimension of a Java array as defined by
3282 * <cite>The Java™ Virtual Machine Specification</cite>.
3283 * The behaviour on a
3284 * {@code null} argument depends on the <a
3285 * href="../util/Formatter.html#syntax">conversion</a>.
3286 *
3287 * @throws java.util.IllegalFormatException
3288 * If a format string contains an illegal syntax, a format
3289 * specifier that is incompatible with the given arguments,
3290 * insufficient arguments given the format string, or other
3291 * illegal conditions. For specification of all possible
3292 * formatting errors, see the <a
3293 * href="../util/Formatter.html#detail">Details</a> section of the
3294 * formatter class specification.
3295 *
3296 * @return A formatted string
3297 *
3298 * @see java.util.Formatter
3299 * @since 1.5
3300 */
3301 public static String format(String format, Object... args) {
3302 return new Formatter().format(format, args).toString();
3303 }
3304
3305 /**
3306 * Returns a formatted string using the specified locale, format string,
3307 * and arguments.
3308 *
3309 * @param l
3310 * The {@linkplain java.util.Locale locale} to apply during
3311 * formatting. If {@code l} is {@code null} then no localization
3312 * is applied.
3313 *
3314 * @param format
3315 * A <a href="../util/Formatter.html#syntax">format string</a>
3316 *
3317 * @param args
3318 * Arguments referenced by the format specifiers in the format
3319 * string. If there are more arguments than format specifiers, the
3320 * extra arguments are ignored. The number of arguments is
3321 * variable and may be zero. The maximum number of arguments is
3322 * limited by the maximum dimension of a Java array as defined by
3323 * <cite>The Java™ Virtual Machine Specification</cite>.
3324 * The behaviour on a
3325 * {@code null} argument depends on the
3326 * <a href="../util/Formatter.html#syntax">conversion</a>.
3327 *
3328 * @throws java.util.IllegalFormatException
3329 * If a format string contains an illegal syntax, a format
3330 * specifier that is incompatible with the given arguments,
3331 * insufficient arguments given the format string, or other
3332 * illegal conditions. For specification of all possible
3333 * formatting errors, see the <a
3334 * href="../util/Formatter.html#detail">Details</a> section of the
3335 * formatter class specification
3336 *
3337 * @return A formatted string
3338 *
3339 * @see java.util.Formatter
3340 * @since 1.5
3341 */
3342 public static String format(Locale l, String format, Object... args) {
3343 return new Formatter(l).format(format, args).toString();
3344 }
3345
3346 /**
3347 * {@preview Associated with text blocks, a preview feature of
3348 * the Java language.
3349 *
3350 * This method is associated with <i>text blocks</i>, a preview
3351 * feature of the Java language. Programs can only use this
3352 * method when preview features are enabled. Preview features
3353 * may be removed in a future release, or upgraded to permanent
3354 * features of the Java language.}
3355 *
3356 * Formats using this string as the format string, and the supplied
3357 * arguments.
3358 *
3359 * @implSpec This method is equivalent to {@code String.format(this, args)}.
3360 *
3361 * @param args
3362 * Arguments referenced by the format specifiers in this string.
3363 *
3364 * @return A formatted string
3365 *
3366 * @see java.lang.String#format(String,Object...)
3367 * @see java.util.Formatter
3368 *
3369 * @since 13
3370 *
3371 */
3372 @jdk.internal.PreviewFeature(feature=jdk.internal.PreviewFeature.Feature.TEXT_BLOCKS,
3373 essentialAPI=true)
3374 public String formatted(Object... args) {
3375 return new Formatter().format(this, args).toString();
3376 }
3377
3378 /**
3379 * Returns the string representation of the {@code Object} argument.
3380 *
3381 * @param obj an {@code Object}.
3382 * @return if the argument is {@code null}, then a string equal to
3383 * {@code "null"}; otherwise, the value of
3384 * {@code obj.toString()} is returned.
3385 * @see java.lang.Object#toString()
3386 */
3387 public static String valueOf(Object obj) {
3388 return (obj == null) ? "null" : obj.toString();
3389 }
3390
3391 /**
3392 * Returns the string representation of the {@code char} array
3393 * argument. The contents of the character array are copied; subsequent
3394 * modification of the character array does not affect the returned
3395 * string.
3396 *
3397 * @param data the character array.
3398 * @return a {@code String} that contains the characters of the
3399 * character array.
3400 */
3401 public static String valueOf(char data[]) {
3402 return new String(data);
3403 }
3404
3405 /**
3406 * Returns the string representation of a specific subarray of the
3407 * {@code char} array argument.
3408 * <p>
3409 * The {@code offset} argument is the index of the first
3410 * character of the subarray. The {@code count} argument
3411 * specifies the length of the subarray. The contents of the subarray
3412 * are copied; subsequent modification of the character array does not
3413 * affect the returned string.
3414 *
3415 * @param data the character array.
3416 * @param offset initial offset of the subarray.
3417 * @param count length of the subarray.
3418 * @return a {@code String} that contains the characters of the
3419 * specified subarray of the character array.
3420 * @throws IndexOutOfBoundsException if {@code offset} is
3421 * negative, or {@code count} is negative, or
3422 * {@code offset+count} is larger than
3423 * {@code data.length}.
3424 */
3425 public static String valueOf(char data[], int offset, int count) {
3426 return new String(data, offset, count);
3427 }
3428
3429 /**
3430 * Equivalent to {@link #valueOf(char[], int, int)}.
3431 *
3432 * @param data the character array.
3433 * @param offset initial offset of the subarray.
3434 * @param count length of the subarray.
3435 * @return a {@code String} that contains the characters of the
3436 * specified subarray of the character array.
3437 * @throws IndexOutOfBoundsException if {@code offset} is
3438 * negative, or {@code count} is negative, or
3439 * {@code offset+count} is larger than
3440 * {@code data.length}.
3441 */
3442 public static String copyValueOf(char data[], int offset, int count) {
3443 return new String(data, offset, count);
3444 }
3445
3446 /**
3447 * Equivalent to {@link #valueOf(char[])}.
3448 *
3449 * @param data the character array.
3450 * @return a {@code String} that contains the characters of the
3451 * character array.
3452 */
3453 public static String copyValueOf(char data[]) {
3454 return new String(data);
3455 }
3456
3457 /**
3458 * Returns the string representation of the {@code boolean} argument.
3459 *
3460 * @param b a {@code boolean}.
3461 * @return if the argument is {@code true}, a string equal to
3462 * {@code "true"} is returned; otherwise, a string equal to
3463 * {@code "false"} is returned.
3464 */
3465 public static String valueOf(boolean b) {
3466 return b ? "true" : "false";
3467 }
3468
3469 /**
3470 * Returns the string representation of the {@code char}
3471 * argument.
3472 *
3473 * @param c a {@code char}.
3474 * @return a string of length {@code 1} containing
3475 * as its single character the argument {@code c}.
3476 */
3477 public static String valueOf(char c) {
3478 if (COMPACT_STRINGS && StringLatin1.canEncode(c)) {
3479 return new String(StringLatin1.toBytes(c), LATIN1);
3480 }
3481 return new String(StringUTF16.toBytes(c), UTF16);
3482 }
3483
3484 /**
3485 * Returns the string representation of the {@code int} argument.
3486 * <p>
3487 * The representation is exactly the one returned by the
3488 * {@code Integer.toString} method of one argument.
3489 *
3490 * @param i an {@code int}.
3491 * @return a string representation of the {@code int} argument.
3492 * @see java.lang.Integer#toString(int, int)
3493 */
3494 public static String valueOf(int i) {
3495 return Integer.toString(i);
3496 }
3497
3498 /**
3499 * Returns the string representation of the {@code long} argument.
3500 * <p>
3501 * The representation is exactly the one returned by the
3502 * {@code Long.toString} method of one argument.
3503 *
3504 * @param l a {@code long}.
3505 * @return a string representation of the {@code long} argument.
3506 * @see java.lang.Long#toString(long)
3507 */
3508 public static String valueOf(long l) {
3509 return Long.toString(l);
3510 }
3511
3512 /**
3513 * Returns the string representation of the {@code float} argument.
3514 * <p>
3515 * The representation is exactly the one returned by the
3516 * {@code Float.toString} method of one argument.
3517 *
3518 * @param f a {@code float}.
3519 * @return a string representation of the {@code float} argument.
3520 * @see java.lang.Float#toString(float)
3521 */
3522 public static String valueOf(float f) {
3523 return Float.toString(f);
3524 }
3525
3526 /**
3527 * Returns the string representation of the {@code double} argument.
3528 * <p>
3529 * The representation is exactly the one returned by the
3530 * {@code Double.toString} method of one argument.
3531 *
3532 * @param d a {@code double}.
3533 * @return a string representation of the {@code double} argument.
3534 * @see java.lang.Double#toString(double)
3535 */
3536 public static String valueOf(double d) {
3537 return Double.toString(d);
3538 }
3539
3540 /**
3541 * Returns a canonical representation for the string object.
3542 * <p>
3543 * A pool of strings, initially empty, is maintained privately by the
3544 * class {@code String}.
3545 * <p>
3546 * When the intern method is invoked, if the pool already contains a
3547 * string equal to this {@code String} object as determined by
3548 * the {@link #equals(Object)} method, then the string from the pool is
3549 * returned. Otherwise, this {@code String} object is added to the
3550 * pool and a reference to this {@code String} object is returned.
3551 * <p>
3552 * It follows that for any two strings {@code s} and {@code t},
3553 * {@code s.intern() == t.intern()} is {@code true}
3554 * if and only if {@code s.equals(t)} is {@code true}.
3555 * <p>
3556 * All literal strings and string-valued constant expressions are
3557 * interned. String literals are defined in section 3.10.5 of the
3558 * <cite>The Java™ Language Specification</cite>.
3559 *
3560 * @return a string that has the same contents as this string, but is
3561 * guaranteed to be from a pool of unique strings.
3562 * @jls 3.10.5 String Literals
3563 */
3564 public native String intern();
3565
3566 /**
3567 * Returns a string whose value is the concatenation of this
3568 * string repeated {@code count} times.
3569 * <p>
3570 * If this string is empty or count is zero then the empty
3571 * string is returned.
3572 *
3573 * @param count number of times to repeat
3574 *
3575 * @return A string composed of this string repeated
3576 * {@code count} times or the empty string if this
3577 * string is empty or count is zero
3578 *
3579 * @throws IllegalArgumentException if the {@code count} is
3580 * negative.
3581 *
3582 * @since 11
3583 */
3584 public String repeat(int count) {
3585 if (count < 0) {
3586 throw new IllegalArgumentException("count is negative: " + count);
3587 }
3588 if (count == 1) {
3589 return this;
3590 }
3591 final int len = value.length;
3592 if (len == 0 || count == 0) {
3593 return "";
3594 }
3595 if (len == 1) {
3596 final byte[] single = new byte[count];
3597 Arrays.fill(single, value[0]);
3598 return new String(single, coder);
3599 }
3600 if (Integer.MAX_VALUE / count < len) {
3601 throw new OutOfMemoryError("Repeating " + len + " bytes String " + count +
3602 " times will produce a String exceeding maximum size.");
3603 }
3604 final int limit = len * count;
3605 final byte[] multiple = new byte[limit];
3606 System.arraycopy(value, 0, multiple, 0, len);
3607 int copied = len;
3608 for (; copied < limit - copied; copied <<= 1) {
3609 System.arraycopy(multiple, 0, multiple, copied, copied);
3610 }
3611 System.arraycopy(multiple, 0, multiple, copied, limit - copied);
3612 return new String(multiple, coder);
3613 }
3614
3615 ////////////////////////////////////////////////////////////////
3616
3617 /**
3618 * Copy character bytes from this string into dst starting at dstBegin.
3619 * This method doesn't perform any range checking.
3620 *
3621 * Invoker guarantees: dst is in UTF16 (inflate itself for asb), if two
3622 * coders are different, and dst is big enough (range check)
3623 *
3624 * @param dstBegin the char index, not offset of byte[]
3625 * @param coder the coder of dst[]
3626 */
3627 void getBytes(byte dst[], int dstBegin, byte coder) {
3628 if (coder() == coder) {
3629 System.arraycopy(value, 0, dst, dstBegin << coder, value.length);
3630 } else { // this.coder == LATIN && coder == UTF16
3631 StringLatin1.inflate(value, 0, dst, dstBegin, value.length);
3632 }
3633 }
3634
3635 /*
3636 * Package private constructor. Trailing Void argument is there for
3637 * disambiguating it against other (public) constructors.
3638 *
3639 * Stores the char[] value into a byte[] that each byte represents
3640 * the8 low-order bits of the corresponding character, if the char[]
3641 * contains only latin1 character. Or a byte[] that stores all
3642 * characters in their byte sequences defined by the {@code StringUTF16}.
3643 */
3644 String(char[] value, int off, int len, Void sig) {
3645 if (len == 0) {
3646 this.value = "".value;
3647 this.coder = "".coder;
3648 return;
3649 }
3650 if (COMPACT_STRINGS) {
3651 byte[] val = StringUTF16.compress(value, off, len);
3652 if (val != null) {
3653 this.value = val;
3654 this.coder = LATIN1;
3655 return;
3656 }
3657 }
3658 this.coder = UTF16;
3659 this.value = StringUTF16.toBytes(value, off, len);
3660 }
3661
3662 /*
3663 * Package private constructor. Trailing Void argument is there for
3664 * disambiguating it against other (public) constructors.
3665 */
3666 String(AbstractStringBuilder asb, Void sig) {
3667 byte[] val = asb.getValue();
3668 int length = asb.length();
3669 if (asb.isLatin1()) {
3670 this.coder = LATIN1;
3671 this.value = Arrays.copyOfRange(val, 0, length);
3672 } else {
3673 if (COMPACT_STRINGS) {
3674 byte[] buf = StringUTF16.compress(val, 0, length);
3675 if (buf != null) {
3676 this.coder = LATIN1;
3677 this.value = buf;
3678 return;
3679 }
3680 }
3681 this.coder = UTF16;
3682 this.value = Arrays.copyOfRange(val, 0, length << 1);
3683 }
3684 }
3685
3686 /*
3687 * Package private constructor which shares value array for speed.
3688 */
3689 String(byte[] value, byte coder) {
3690 this.value = value;
3691 this.coder = coder;
3692 }
3693
3694 byte coder() {
3695 return COMPACT_STRINGS ? coder : UTF16;
3696 }
3697
3698 byte[] value() {
3699 return value;
3700 }
3701
3702 boolean isLatin1() {
3703 return COMPACT_STRINGS && coder == LATIN1;
3704 }
3705
3706 @Native static final byte LATIN1 = 0;
3707 @Native static final byte UTF16 = 1;
3708
3709 /*
3710 * StringIndexOutOfBoundsException if {@code index} is
3711 * negative or greater than or equal to {@code length}.
3712 */
3713 static void checkIndex(int index, int length) {
3714 if (index < 0 || index >= length) {
3715 throw new StringIndexOutOfBoundsException("index " + index +
3716 ", length " + length);
3717 }
3718 }
3719
3720 /*
3721 * StringIndexOutOfBoundsException if {@code offset}
3722 * is negative or greater than {@code length}.
3723 */
3724 static void checkOffset(int offset, int length) {
3725 if (offset < 0 || offset > length) {
3726 throw new StringIndexOutOfBoundsException("offset " + offset +
3727 ", length " + length);
3728 }
3729 }
3730
3731 /*
3732 * Check {@code offset}, {@code count} against {@code 0} and {@code length}
3733 * bounds.
3734 *
3735 * @throws StringIndexOutOfBoundsException
3736 * If {@code offset} is negative, {@code count} is negative,
3737 * or {@code offset} is greater than {@code length - count}
3738 */
3739 static void checkBoundsOffCount(int offset, int count, int length) {
3740 if (offset < 0 || count < 0 || offset > length - count) {
3741 throw new StringIndexOutOfBoundsException(
3742 "offset " + offset + ", count " + count + ", length " + length);
3743 }
3744 }
3745
3746 /*
3747 * Check {@code begin}, {@code end} against {@code 0} and {@code length}
3748 * bounds.
3749 *
3750 * @throws StringIndexOutOfBoundsException
3751 * If {@code begin} is negative, {@code begin} is greater than
3752 * {@code end}, or {@code end} is greater than {@code length}.
3753 */
3754 static void checkBoundsBeginEnd(int begin, int end, int length) {
3755 if (begin < 0 || begin > end || end > length) {
3756 throw new StringIndexOutOfBoundsException(
3757 "begin " + begin + ", end " + end + ", length " + length);
3758 }
3759 }
3760
3761 /**
3762 * Returns the string representation of the {@code codePoint}
3763 * argument.
3764 *
3765 * @param codePoint a {@code codePoint}.
3766 * @return a string of length {@code 1} or {@code 2} containing
3767 * as its single character the argument {@code codePoint}.
3768 * @throws IllegalArgumentException if the specified
3769 * {@code codePoint} is not a {@linkplain Character#isValidCodePoint
3770 * valid Unicode code point}.
3771 */
3772 static String valueOfCodePoint(int codePoint) {
3773 if (COMPACT_STRINGS && StringLatin1.canEncode(codePoint)) {
3774 return new String(StringLatin1.toBytes((char)codePoint), LATIN1);
3775 } else if (Character.isBmpCodePoint(codePoint)) {
3776 return new String(StringUTF16.toBytes((char)codePoint), UTF16);
3777 } else if (Character.isSupplementaryCodePoint(codePoint)) {
3778 return new String(StringUTF16.toBytesSupplementary(codePoint), UTF16);
3779 }
3780
3781 throw new IllegalArgumentException(
3782 format("Not a valid Unicode code point: 0x%X", codePoint));
3783 }
3784
3785 /**
3786 * Returns an {@link Optional} containing the nominal descriptor for this
3787 * instance, which is the instance itself.
3788 *
3789 * @return an {@link Optional} describing the {@linkplain String} instance
3790 * @since 12
3791 */
3792 @Override
3793 public Optional<String> describeConstable() {
3794 return Optional.of(this);
3795 }
3796
3797 /**
3798 * Resolves this instance as a {@link ConstantDesc}, the result of which is
3799 * the instance itself.
3800 *
3801 * @param lookup ignored
3802 * @return the {@linkplain String} instance
3803 * @since 12
3804 */
3805 @Override
3806 public String resolveConstantDesc(MethodHandles.Lookup lookup) {
3807 return this;
3808 }
3809
3810 }