1 /*
2 * Copyright (c) 1994, 2014, 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.nio.charset.Charset;
31 import java.util.ArrayList;
32 import java.util.Arrays;
33 import java.util.Comparator;
34 import java.util.Formatter;
35 import java.util.Locale;
36 import java.util.Objects;
37 import java.util.StringJoiner;
38 import java.util.regex.Matcher;
39 import java.util.regex.Pattern;
40 import java.util.regex.PatternSyntaxException;
41
42 /**
43 * The {@code String} class represents character strings. All
44 * string literals in Java programs, such as {@code "abc"}, are
45 * implemented as instances of this class.
46 * <p>
47 * Strings are constant; their values cannot be changed after they
48 * are created. String buffers support mutable strings.
49 * Because String objects are immutable they can be shared. For example:
50 * <blockquote><pre>
51 * String str = "abc";
52 * </pre></blockquote><p>
53 * is equivalent to:
54 * <blockquote><pre>
55 * char data[] = {'a', 'b', 'c'};
56 * String str = new String(data);
57 * </pre></blockquote><p>
58 * Here are some more examples of how strings can be used:
59 * <blockquote><pre>
60 * System.out.println("abc");
61 * String cde = "cde";
62 * System.out.println("abc" + cde);
63 * String c = "abc".substring(2,3);
64 * String d = cde.substring(1, 2);
65 * </pre></blockquote>
66 * <p>
67 * The class {@code String} includes methods for examining
68 * individual characters of the sequence, for comparing strings, for
69 * searching strings, for extracting substrings, and for creating a
70 * copy of a string with all characters translated to uppercase or to
71 * lowercase. Case mapping is based on the Unicode Standard version
72 * specified by the {@link java.lang.Character Character} class.
73 * <p>
74 * The Java language provides special support for the string
75 * concatenation operator ( + ), and for conversion of
76 * other objects to strings. String concatenation is implemented
77 * through the {@code StringBuilder}(or {@code StringBuffer})
78 * class and its {@code append} method.
79 * String conversions are implemented through the method
80 * {@code toString}, defined by {@code Object} and
81 * inherited by all classes in Java. For additional information on
82 * string concatenation and conversion, see Gosling, Joy, and Steele,
83 * <i>The Java Language Specification</i>.
84 *
85 * <p> Unless otherwise noted, passing a <tt>null</tt> argument to a constructor
86 * or method in this class will cause a {@link NullPointerException} to be
87 * thrown.
88 *
89 * <p>A {@code String} represents a string in the UTF-16 format
90 * in which <em>supplementary characters</em> are represented by <em>surrogate
91 * pairs</em> (see the section <a href="Character.html#unicode">Unicode
92 * Character Representations</a> in the {@code Character} class for
93 * more information).
94 * Index values refer to {@code char} code units, so a supplementary
95 * character uses two positions in a {@code String}.
96 * <p>The {@code String} class provides methods for dealing with
97 * Unicode code points (i.e., characters), in addition to those for
98 * dealing with Unicode code units (i.e., {@code char} values).
99 *
100 * @author Lee Boynton
101 * @author Arthur van Hoff
102 * @author Martin Buchholz
103 * @author Ulf Zibis
104 * @see java.lang.Object#toString()
105 * @see java.lang.StringBuffer
106 * @see java.lang.StringBuilder
107 * @see java.nio.charset.Charset
108 * @since 1.0
109 */
110
111 public final class String
112 implements java.io.Serializable, Comparable<String>, CharSequence {
113 /** The value is used for character storage. */
114 private final char value[];
115
116 /** Cache the hash code for the string */
117 private int hash; // Default to 0
118
119 /** use serialVersionUID from JDK 1.0.2 for interoperability */
120 private static final long serialVersionUID = -6849794470754667710L;
121
122 /**
123 * Class String is special cased within the Serialization Stream Protocol.
124 *
125 * A String instance is written into an ObjectOutputStream according to
126 * <a href="{@docRoot}/../platform/serialization/spec/output.html">
127 * Object Serialization Specification, Section 6.2, "Stream Elements"</a>
128 */
129 private static final ObjectStreamField[] serialPersistentFields =
130 new ObjectStreamField[0];
131
132 /**
133 * Initializes a newly created {@code String} object so that it represents
134 * an empty character sequence. Note that use of this constructor is
135 * unnecessary since Strings are immutable.
136 */
137 public String() {
138 this.value = "".value;
139 }
140
141 /**
142 * Initializes a newly created {@code String} object so that it represents
143 * the same sequence of characters as the argument; in other words, the
144 * newly created string is a copy of the argument string. Unless an
145 * explicit copy of {@code original} is needed, use of this constructor is
146 * unnecessary since Strings are immutable.
147 *
148 * @param original
149 * A {@code String}
150 */
151 public String(String original) {
152 this.value = original.value;
153 this.hash = original.hash;
154 }
155
156 /**
157 * Allocates a new {@code String} so that it represents the sequence of
158 * characters currently contained in the character array argument. The
159 * contents of the character array are copied; subsequent modification of
160 * the character array does not affect the newly created string.
161 *
162 * @param value
163 * The initial value of the string
164 */
165 public String(char value[]) {
166 this.value = Arrays.copyOf(value, value.length);
167 }
168
169 /**
170 * Allocates a new {@code String} that contains characters from a subarray
171 * of the character array argument. The {@code offset} argument is the
172 * index of the first character of the subarray and the {@code count}
173 * argument specifies the length of the subarray. The contents of the
174 * subarray are copied; subsequent modification of the character array does
175 * not affect the newly created string.
176 *
177 * @param value
178 * Array that is the source of characters
179 *
180 * @param offset
181 * The initial offset
182 *
183 * @param count
184 * The length
185 *
186 * @throws IndexOutOfBoundsException
187 * If {@code offset} is negative, {@code count} is negative, or
188 * {@code offset} is greater than {@code value.length - count}
189 */
190 public String(char value[], int offset, int count) {
191 if (offset < 0) {
192 throw new StringIndexOutOfBoundsException(offset);
193 }
194 if (count <= 0) {
195 if (count == 0) {
196 this.value = "".value;
197 return;
198 }
199 throw new StringIndexOutOfBoundsException(count);
200 }
201 // Note: offset or count might be near -1>>>1.
202 if (offset > value.length - count) {
203 throw new StringIndexOutOfBoundsException(offset + count);
204 }
205 this.value = Arrays.copyOfRange(value, offset, offset+count);
206 }
207
208 /**
209 * Allocates a new {@code String} that contains characters from a subarray
210 * of the <a href="Character.html#unicode">Unicode code point</a> array
211 * argument. The {@code offset} argument is the index of the first code
212 * point of the subarray and the {@code count} argument specifies the
213 * length of the subarray. The contents of the subarray are converted to
214 * {@code char}s; subsequent modification of the {@code int} array does not
215 * affect the newly created string.
216 *
217 * @param codePoints
218 * Array that is the source of Unicode code points
219 *
220 * @param offset
221 * The initial offset
222 *
223 * @param count
224 * The length
225 *
226 * @throws IllegalArgumentException
227 * If any invalid Unicode code point is found in {@code
228 * codePoints}
229 *
230 * @throws IndexOutOfBoundsException
231 * If {@code offset} is negative, {@code count} is negative, or
232 * {@code offset} is greater than {@code codePoints.length - count}
233 *
234 * @since 1.5
235 */
236 public String(int[] codePoints, int offset, int count) {
237 if (offset < 0) {
238 throw new StringIndexOutOfBoundsException(offset);
239 }
240 if (count <= 0) {
241 if (count == 0) {
242 this.value = "".value;
243 return;
244 }
245 throw new StringIndexOutOfBoundsException(count);
246 }
247 // Note: offset or count might be near -1>>>1.
248 if (offset > codePoints.length - count) {
249 throw new StringIndexOutOfBoundsException(offset + count);
250 }
251
252 final int end = offset + count;
253
254 // Pass 1: Compute precise size of char[]
255 int n = count;
256 for (int i = offset; i < end; i++) {
257 int c = codePoints[i];
258 if (Character.isBmpCodePoint(c))
259 continue;
260 else if (Character.isValidCodePoint(c))
261 n++;
262 else throw new IllegalArgumentException(Integer.toString(c));
263 }
264
265 // Pass 2: Allocate and fill in char[]
266 final char[] v = new char[n];
267
268 for (int i = offset, j = 0; i < end; i++, j++) {
269 int c = codePoints[i];
270 if (Character.isBmpCodePoint(c))
271 v[j] = (char)c;
272 else
273 Character.toSurrogates(c, v, j++);
274 }
275
276 this.value = v;
277 }
278
279 /**
280 * Allocates a new {@code String} constructed from a subarray of an array
281 * of 8-bit integer values.
282 *
283 * <p> The {@code offset} argument is the index of the first byte of the
284 * subarray, and the {@code count} argument specifies the length of the
285 * subarray.
286 *
287 * <p> Each {@code byte} in the subarray is converted to a {@code char} as
288 * specified in the method above.
289 *
290 * @deprecated This method does not properly convert bytes into characters.
291 * As of JDK 1.1, the preferred way to do this is via the
292 * {@code String} constructors that take a {@link
293 * java.nio.charset.Charset}, charset name, or that use the platform's
294 * default charset.
295 *
296 * @param ascii
297 * The bytes to be converted to characters
298 *
299 * @param hibyte
300 * The top 8 bits of each 16-bit Unicode code unit
301 *
302 * @param offset
303 * The initial offset
304 * @param count
305 * The length
306 *
307 * @throws IndexOutOfBoundsException
308 * If {@code offset} is negative, {@code count} is negative, or
309 * {@code offset} is greater than {@code ascii.length - count}
310 *
311 * @see #String(byte[], int)
312 * @see #String(byte[], int, int, java.lang.String)
313 * @see #String(byte[], int, int, java.nio.charset.Charset)
314 * @see #String(byte[], int, int)
315 * @see #String(byte[], java.lang.String)
316 * @see #String(byte[], java.nio.charset.Charset)
317 * @see #String(byte[])
318 */
319 @Deprecated
320 public String(byte ascii[], int hibyte, int offset, int count) {
321 checkBounds(ascii, offset, count);
322 char value[] = new char[count];
323
324 if (hibyte == 0) {
325 for (int i = count; i-- > 0;) {
326 value[i] = (char)(ascii[i + offset] & 0xff);
327 }
328 } else {
329 hibyte <<= 8;
330 for (int i = count; i-- > 0;) {
331 value[i] = (char)(hibyte | (ascii[i + offset] & 0xff));
332 }
333 }
334 this.value = value;
335 }
336
337 /**
338 * Allocates a new {@code String} containing characters constructed from
339 * an array of 8-bit integer values. Each character <i>c</i>in the
340 * resulting string is constructed from the corresponding component
341 * <i>b</i> in the byte array such that:
342 *
343 * <blockquote><pre>
344 * <b><i>c</i></b> == (char)(((hibyte & 0xff) << 8)
345 * | (<b><i>b</i></b> & 0xff))
346 * </pre></blockquote>
347 *
348 * @deprecated This method does not properly convert bytes into
349 * characters. As of JDK 1.1, the preferred way to do this is via the
350 * {@code String} constructors that take a {@link
351 * java.nio.charset.Charset}, charset name, or that use the platform's
352 * default charset.
353 *
354 * @param ascii
355 * The bytes to be converted to characters
356 *
357 * @param hibyte
358 * The top 8 bits of each 16-bit Unicode code unit
359 *
360 * @see #String(byte[], int, int, java.lang.String)
361 * @see #String(byte[], int, int, java.nio.charset.Charset)
362 * @see #String(byte[], int, int)
363 * @see #String(byte[], java.lang.String)
364 * @see #String(byte[], java.nio.charset.Charset)
365 * @see #String(byte[])
366 */
367 @Deprecated
368 public String(byte ascii[], int hibyte) {
369 this(ascii, hibyte, 0, ascii.length);
370 }
371
372 /* Common private utility method used to bounds check the byte array
373 * and requested offset & length values used by the String(byte[],..)
374 * constructors.
375 */
376 private static void checkBounds(byte[] bytes, int offset, int length) {
377 if (length < 0)
378 throw new StringIndexOutOfBoundsException(length);
379 if (offset < 0)
380 throw new StringIndexOutOfBoundsException(offset);
381 if (offset > bytes.length - length)
382 throw new StringIndexOutOfBoundsException(offset + length);
383 }
384
385 /**
386 * Constructs a new {@code String} by decoding the specified subarray of
387 * bytes using the specified charset. The length of the new {@code String}
388 * is a function of the charset, and hence may not be equal to the length
389 * of the subarray.
390 *
391 * <p> The behavior of this constructor when the given bytes are not valid
392 * in the given charset is unspecified. The {@link
393 * java.nio.charset.CharsetDecoder} class should be used when more control
394 * over the decoding process is required.
395 *
396 * @param bytes
397 * The bytes to be decoded into characters
398 *
399 * @param offset
400 * The index of the first byte to decode
401 *
402 * @param length
403 * The number of bytes to decode
404
405 * @param charsetName
406 * The name of a supported {@linkplain java.nio.charset.Charset
407 * charset}
408 *
409 * @throws UnsupportedEncodingException
410 * If the named charset is not supported
411 *
412 * @throws IndexOutOfBoundsException
413 * If {@code offset} is negative, {@code length} is negative, or
414 * {@code offset} is greater than {@code bytes.length - length}
415 *
416 * @since 1.1
417 */
418 public String(byte bytes[], int offset, int length, String charsetName)
419 throws UnsupportedEncodingException {
420 if (charsetName == null)
421 throw new NullPointerException("charsetName");
422 checkBounds(bytes, offset, length);
423 this.value = StringCoding.decode(charsetName, bytes, offset, length);
424 }
425
426 /**
427 * Constructs a new {@code String} by decoding the specified subarray of
428 * bytes using the specified {@linkplain java.nio.charset.Charset charset}.
429 * The length of the new {@code String} is a function of the charset, and
430 * hence may not be equal to the length of the subarray.
431 *
432 * <p> This method always replaces malformed-input and unmappable-character
433 * sequences with this charset's default replacement string. The {@link
434 * java.nio.charset.CharsetDecoder} class should be used when more control
435 * over the decoding process is required.
436 *
437 * @param bytes
438 * The bytes to be decoded into characters
439 *
440 * @param offset
441 * The index of the first byte to decode
442 *
443 * @param length
444 * The number of bytes to decode
445 *
446 * @param charset
447 * The {@linkplain java.nio.charset.Charset charset} to be used to
448 * decode the {@code bytes}
449 *
450 * @throws IndexOutOfBoundsException
451 * If {@code offset} is negative, {@code length} is negative, or
452 * {@code offset} is greater than {@code bytes.length - length}
453 *
454 * @since 1.6
455 */
456 public String(byte bytes[], int offset, int length, Charset charset) {
457 if (charset == null)
458 throw new NullPointerException("charset");
459 checkBounds(bytes, offset, length);
460 this.value = StringCoding.decode(charset, bytes, offset, length);
461 }
462
463 /**
464 * Constructs a new {@code String} by decoding the specified array of bytes
465 * using the specified {@linkplain java.nio.charset.Charset charset}. The
466 * length of the new {@code String} is a function of the charset, and hence
467 * may not be equal to the length of the byte array.
468 *
469 * <p> The behavior of this constructor when the given bytes are not valid
470 * in the given charset is unspecified. The {@link
471 * java.nio.charset.CharsetDecoder} class should be used when more control
472 * over the decoding process is required.
473 *
474 * @param bytes
475 * The bytes to be decoded into characters
476 *
477 * @param charsetName
478 * The name of a supported {@linkplain java.nio.charset.Charset
479 * charset}
480 *
481 * @throws UnsupportedEncodingException
482 * If the named charset is not supported
483 *
484 * @since 1.1
485 */
486 public String(byte bytes[], String charsetName)
487 throws UnsupportedEncodingException {
488 this(bytes, 0, bytes.length, charsetName);
489 }
490
491 /**
492 * Constructs a new {@code String} by decoding the specified array of
493 * bytes using the specified {@linkplain java.nio.charset.Charset charset}.
494 * The length of the new {@code String} is a function of the charset, and
495 * hence may not be equal to the length of the byte array.
496 *
497 * <p> This method always replaces malformed-input and unmappable-character
498 * sequences with this charset's default replacement string. The {@link
499 * java.nio.charset.CharsetDecoder} class should be used when more control
500 * over the decoding process is required.
501 *
502 * @param bytes
503 * The bytes to be decoded into characters
504 *
505 * @param charset
506 * The {@linkplain java.nio.charset.Charset charset} to be used to
507 * decode the {@code bytes}
508 *
509 * @since 1.6
510 */
511 public String(byte bytes[], Charset charset) {
512 this(bytes, 0, bytes.length, charset);
513 }
514
515 /**
516 * Constructs a new {@code String} by decoding the specified subarray of
517 * bytes using the platform's default charset. The length of the new
518 * {@code String} is a function of the charset, and hence may not be equal
519 * to the length of the subarray.
520 *
521 * <p> The behavior of this constructor when the given bytes are not valid
522 * in the default charset is unspecified. The {@link
523 * java.nio.charset.CharsetDecoder} class should be used when more control
524 * over the decoding process is required.
525 *
526 * @param bytes
527 * The bytes to be decoded into characters
528 *
529 * @param offset
530 * The index of the first byte to decode
531 *
532 * @param length
533 * The number of bytes to decode
534 *
535 * @throws IndexOutOfBoundsException
536 * If {@code offset} is negative, {@code length} is negative, or
537 * {@code offset} is greater than {@code bytes.length - length}
538 *
539 * @since 1.1
540 */
541 public String(byte bytes[], int offset, int length) {
542 checkBounds(bytes, offset, length);
543 this.value = StringCoding.decode(bytes, offset, length);
544 }
545
546 /**
547 * Constructs a new {@code String} by decoding the specified array of bytes
548 * using the platform's default charset. The length of the new {@code
549 * String} is a function of the charset, and hence may not be equal to the
550 * length of the byte array.
551 *
552 * <p> The behavior of this constructor when the given bytes are not valid
553 * in the default charset is unspecified. The {@link
554 * java.nio.charset.CharsetDecoder} class should be used when more control
555 * over the decoding process is required.
556 *
557 * @param bytes
558 * The bytes to be decoded into characters
559 *
560 * @since 1.1
561 */
562 public String(byte bytes[]) {
563 this(bytes, 0, bytes.length);
564 }
565
566 /**
567 * Allocates a new string that contains the sequence of characters
568 * currently contained in the string buffer argument. The contents of the
569 * string buffer are copied; subsequent modification of the string buffer
570 * does not affect the newly created string.
571 *
572 * @param buffer
573 * A {@code StringBuffer}
574 */
575 public String(StringBuffer buffer) {
576 synchronized(buffer) {
577 this.value = Arrays.copyOf(buffer.getValue(), buffer.length());
578 }
579 }
580
581 /**
582 * Allocates a new string that contains the sequence of characters
583 * currently contained in the string builder argument. The contents of the
584 * string builder are copied; subsequent modification of the string builder
585 * does not affect the newly created string.
586 *
587 * <p> This constructor is provided to ease migration to {@code
588 * StringBuilder}. Obtaining a string from a string builder via the {@code
589 * toString} method is likely to run faster and is generally preferred.
590 *
591 * @param builder
592 * A {@code StringBuilder}
593 *
594 * @since 1.5
595 */
596 public String(StringBuilder builder) {
597 this.value = Arrays.copyOf(builder.getValue(), builder.length());
598 }
599
600 /*
601 * Package private constructor which shares value array for speed.
602 * this constructor is always expected to be called with share==true.
603 * a separate constructor is needed because we already have a public
604 * String(char[]) constructor that makes a copy of the given char[].
605 */
606 String(char[] value, boolean share) {
607 // assert share : "unshared not supported";
608 this.value = value;
609 }
610
611 /**
612 * Returns the length of this string.
613 * The length is equal to the number of <a href="Character.html#unicode">Unicode
614 * code units</a> in the string.
615 *
616 * @return the length of the sequence of characters represented by this
617 * object.
618 */
619 public int length() {
620 return value.length;
621 }
622
623 /**
624 * Returns {@code true} if, and only if, {@link #length()} is {@code 0}.
625 *
626 * @return {@code true} if {@link #length()} is {@code 0}, otherwise
627 * {@code false}
628 *
629 * @since 1.6
630 */
631 public boolean isEmpty() {
632 return value.length == 0;
633 }
634
635 /**
636 * Returns the {@code char} value at the
637 * specified index. An index ranges from {@code 0} to
638 * {@code length() - 1}. The first {@code char} value of the sequence
639 * is at index {@code 0}, the next at index {@code 1},
640 * and so on, as for array indexing.
641 *
642 * <p>If the {@code char} value specified by the index is a
643 * <a href="Character.html#unicode">surrogate</a>, the surrogate
644 * value is returned.
645 *
646 * @param index the index of the {@code char} value.
647 * @return the {@code char} value at the specified index of this string.
648 * The first {@code char} value is at index {@code 0}.
649 * @exception IndexOutOfBoundsException if the {@code index}
650 * argument is negative or not less than the length of this
651 * string.
652 */
653 public char charAt(int index) {
654 if ((index < 0) || (index >= value.length)) {
655 throw new StringIndexOutOfBoundsException(index);
656 }
657 return value[index];
658 }
659
660 /**
661 * Returns the character (Unicode code point) at the specified
662 * index. The index refers to {@code char} values
663 * (Unicode code units) and ranges from {@code 0} to
664 * {@link #length()}{@code - 1}.
665 *
666 * <p> If the {@code char} value specified at the given index
667 * is in the high-surrogate range, the following index is less
668 * than the length of this {@code String}, and the
669 * {@code char} value at the following index is in the
670 * low-surrogate range, then the supplementary code point
671 * corresponding to this surrogate pair is returned. Otherwise,
672 * the {@code char} value at the given index is returned.
673 *
674 * @param index the index to the {@code char} values
675 * @return the code point value of the character at the
676 * {@code index}
677 * @exception IndexOutOfBoundsException if the {@code index}
678 * argument is negative or not less than the length of this
679 * string.
680 * @since 1.5
681 */
682 public int codePointAt(int index) {
683 if ((index < 0) || (index >= value.length)) {
684 throw new StringIndexOutOfBoundsException(index);
685 }
686 return Character.codePointAtImpl(value, index, value.length);
687 }
688
689 /**
690 * Returns the character (Unicode code point) before the specified
691 * index. The index refers to {@code char} values
692 * (Unicode code units) and ranges from {@code 1} to {@link
693 * CharSequence#length() length}.
694 *
695 * <p> If the {@code char} value at {@code (index - 1)}
696 * is in the low-surrogate range, {@code (index - 2)} is not
697 * negative, and the {@code char} value at {@code (index -
698 * 2)} is in the high-surrogate range, then the
699 * supplementary code point value of the surrogate pair is
700 * returned. If the {@code char} value at {@code index -
701 * 1} is an unpaired low-surrogate or a high-surrogate, the
702 * surrogate value is returned.
703 *
704 * @param index the index following the code point that should be returned
705 * @return the Unicode code point value before the given index.
706 * @exception IndexOutOfBoundsException if the {@code index}
707 * argument is less than 1 or greater than the length
708 * of this string.
709 * @since 1.5
710 */
711 public int codePointBefore(int index) {
712 int i = index - 1;
713 if ((i < 0) || (i >= value.length)) {
714 throw new StringIndexOutOfBoundsException(index);
715 }
716 return Character.codePointBeforeImpl(value, index, 0);
717 }
718
719 /**
720 * Returns the number of Unicode code points in the specified text
721 * range of this {@code String}. The text range begins at the
722 * specified {@code beginIndex} and extends to the
723 * {@code char} at index {@code endIndex - 1}. Thus the
724 * length (in {@code char}s) of the text range is
725 * {@code endIndex-beginIndex}. Unpaired surrogates within
726 * the text range count as one code point each.
727 *
728 * @param beginIndex the index to the first {@code char} of
729 * the text range.
730 * @param endIndex the index after the last {@code char} of
731 * the text range.
732 * @return the number of Unicode code points in the specified text
733 * range
734 * @exception IndexOutOfBoundsException if the
735 * {@code beginIndex} is negative, or {@code endIndex}
736 * is larger than the length of this {@code String}, or
737 * {@code beginIndex} is larger than {@code endIndex}.
738 * @since 1.5
739 */
740 public int codePointCount(int beginIndex, int endIndex) {
741 if (beginIndex < 0 || endIndex > value.length || beginIndex > endIndex) {
742 throw new IndexOutOfBoundsException();
743 }
744 return Character.codePointCountImpl(value, beginIndex, endIndex - beginIndex);
745 }
746
747 /**
748 * Returns the index within this {@code String} that is
749 * offset from the given {@code index} by
750 * {@code codePointOffset} code points. Unpaired surrogates
751 * within the text range given by {@code index} and
752 * {@code codePointOffset} count as one code point each.
753 *
754 * @param index the index to be offset
755 * @param codePointOffset the offset in code points
756 * @return the index within this {@code String}
757 * @exception IndexOutOfBoundsException if {@code index}
758 * is negative or larger then the length of this
759 * {@code String}, or if {@code codePointOffset} is positive
760 * and the substring starting with {@code index} has fewer
761 * than {@code codePointOffset} code points,
762 * or if {@code codePointOffset} is negative and the substring
763 * before {@code index} has fewer than the absolute value
764 * of {@code codePointOffset} code points.
765 * @since 1.5
766 */
767 public int offsetByCodePoints(int index, int codePointOffset) {
768 if (index < 0 || index > value.length) {
769 throw new IndexOutOfBoundsException();
770 }
771 return Character.offsetByCodePointsImpl(value, 0, value.length,
772 index, codePointOffset);
773 }
774
775 /**
776 * Copy characters from this string into dst starting at dstBegin.
777 * This method doesn't perform any range checking.
778 */
779 void getChars(char dst[], int dstBegin) {
780 System.arraycopy(value, 0, dst, dstBegin, value.length);
781 }
782
783 /**
784 * Copies characters from this string into the destination character
785 * array.
786 * <p>
787 * The first character to be copied is at index {@code srcBegin};
788 * the last character to be copied is at index {@code srcEnd-1}
789 * (thus the total number of characters to be copied is
790 * {@code srcEnd-srcBegin}). The characters are copied into the
791 * subarray of {@code dst} starting at index {@code dstBegin}
792 * and ending at index:
793 * <blockquote><pre>
794 * dstbegin + (srcEnd-srcBegin) - 1
795 * </pre></blockquote>
796 *
797 * @param srcBegin index of the first character in the string
798 * to copy.
799 * @param srcEnd index after the last character in the string
800 * to copy.
801 * @param dst the destination array.
802 * @param dstBegin the start offset in the destination array.
803 * @exception IndexOutOfBoundsException If any of the following
804 * is true:
805 * <ul><li>{@code srcBegin} is negative.
806 * <li>{@code srcBegin} is greater than {@code srcEnd}
807 * <li>{@code srcEnd} is greater than the length of this
808 * string
809 * <li>{@code dstBegin} is negative
810 * <li>{@code dstBegin+(srcEnd-srcBegin)} is larger than
811 * {@code dst.length}</ul>
812 */
813 public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin) {
814 if (srcBegin < 0) {
815 throw new StringIndexOutOfBoundsException(srcBegin);
816 }
817 if (srcEnd > value.length) {
818 throw new StringIndexOutOfBoundsException(srcEnd);
819 }
820 if (srcBegin > srcEnd) {
821 throw new StringIndexOutOfBoundsException(srcEnd - srcBegin);
822 }
823 System.arraycopy(value, srcBegin, dst, dstBegin, srcEnd - srcBegin);
824 }
825
826 /**
827 * Copies characters from this string into the destination byte array. Each
828 * byte receives the 8 low-order bits of the corresponding character. The
829 * eight high-order bits of each character are not copied and do not
830 * participate in the transfer in any way.
831 *
832 * <p> The first character to be copied is at index {@code srcBegin}; the
833 * last character to be copied is at index {@code srcEnd-1}. The total
834 * number of characters to be copied is {@code srcEnd-srcBegin}. The
835 * characters, converted to bytes, are copied into the subarray of {@code
836 * dst} starting at index {@code dstBegin} and ending at index:
837 *
838 * <blockquote><pre>
839 * dstbegin + (srcEnd-srcBegin) - 1
840 * </pre></blockquote>
841 *
842 * @deprecated This method does not properly convert characters into
843 * bytes. As of JDK 1.1, the preferred way to do this is via the
844 * {@link #getBytes()} method, which uses the platform's default charset.
845 *
846 * @param srcBegin
847 * Index of the first character in the string to copy
848 *
849 * @param srcEnd
850 * Index after the last character in the string to copy
851 *
852 * @param dst
853 * The destination array
854 *
855 * @param dstBegin
856 * The start offset in the destination array
857 *
858 * @throws IndexOutOfBoundsException
859 * If any of the following is true:
860 * <ul>
861 * <li> {@code srcBegin} is negative
862 * <li> {@code srcBegin} is greater than {@code srcEnd}
863 * <li> {@code srcEnd} is greater than the length of this String
864 * <li> {@code dstBegin} is negative
865 * <li> {@code dstBegin+(srcEnd-srcBegin)} is larger than {@code
866 * dst.length}
867 * </ul>
868 */
869 @Deprecated
870 public void getBytes(int srcBegin, int srcEnd, byte dst[], int dstBegin) {
871 if (srcBegin < 0) {
872 throw new StringIndexOutOfBoundsException(srcBegin);
873 }
874 if (srcEnd > value.length) {
875 throw new StringIndexOutOfBoundsException(srcEnd);
876 }
877 if (srcBegin > srcEnd) {
878 throw new StringIndexOutOfBoundsException(srcEnd - srcBegin);
879 }
880 Objects.requireNonNull(dst);
881
882 int j = dstBegin;
883 int n = srcEnd;
884 int i = srcBegin;
885 char[] val = value; /* avoid getfield opcode */
886
887 while (i < n) {
888 dst[j++] = (byte)val[i++];
889 }
890 }
891
892 /**
893 * Encodes this {@code String} into a sequence of bytes using the named
894 * charset, storing the result into a new byte array.
895 *
896 * <p> The behavior of this method when this string cannot be encoded in
897 * the given charset is unspecified. The {@link
898 * java.nio.charset.CharsetEncoder} class should be used when more control
899 * over the encoding process is required.
900 *
901 * @param charsetName
902 * The name of a supported {@linkplain java.nio.charset.Charset
903 * charset}
904 *
905 * @return The resultant byte array
906 *
907 * @throws UnsupportedEncodingException
908 * If the named charset is not supported
909 *
910 * @since 1.1
911 */
912 public byte[] getBytes(String charsetName)
913 throws UnsupportedEncodingException {
914 if (charsetName == null) throw new NullPointerException();
915 return StringCoding.encode(charsetName, value, 0, value.length);
916 }
917
918 /**
919 * Encodes this {@code String} into a sequence of bytes using the given
920 * {@linkplain java.nio.charset.Charset charset}, storing the result into a
921 * new byte array.
922 *
923 * <p> This method always replaces malformed-input and unmappable-character
924 * sequences with this charset's default replacement byte array. The
925 * {@link java.nio.charset.CharsetEncoder} class should be used when more
926 * control over the encoding process is required.
927 *
928 * @param charset
929 * The {@linkplain java.nio.charset.Charset} to be used to encode
930 * the {@code String}
931 *
932 * @return The resultant byte array
933 *
934 * @since 1.6
935 */
936 public byte[] getBytes(Charset charset) {
937 if (charset == null) throw new NullPointerException();
938 return StringCoding.encode(charset, value, 0, value.length);
939 }
940
941 /**
942 * Encodes this {@code String} into a sequence of bytes using the
943 * platform's default charset, storing the result into a new byte array.
944 *
945 * <p> The behavior of this method when this string cannot be encoded in
946 * the default charset is unspecified. The {@link
947 * java.nio.charset.CharsetEncoder} class should be used when more control
948 * over the encoding process is required.
949 *
950 * @return The resultant byte array
951 *
952 * @since 1.1
953 */
954 public byte[] getBytes() {
955 return StringCoding.encode(value, 0, value.length);
956 }
957
958 /**
959 * Compares this string to the specified object. The result is {@code
960 * true} if and only if the argument is not {@code null} and is a {@code
961 * String} object that represents the same sequence of characters as this
962 * object.
963 *
964 * @param anObject
965 * The object to compare this {@code String} against
966 *
967 * @return {@code true} if the given object represents a {@code String}
968 * equivalent to this string, {@code false} otherwise
969 *
970 * @see #compareTo(String)
971 * @see #equalsIgnoreCase(String)
972 */
973 public boolean equals(Object anObject) {
974 if (this == anObject) {
975 return true;
976 }
977 if (anObject instanceof String) {
978 String anotherString = (String)anObject;
979 int n = value.length;
980 if (n == anotherString.value.length) {
981 char v1[] = value;
982 char v2[] = anotherString.value;
983 int i = 0;
984 while (n-- != 0) {
985 if (v1[i] != v2[i])
986 return false;
987 i++;
988 }
989 return true;
990 }
991 }
992 return false;
993 }
994
995 /**
996 * Compares this string to the specified {@code StringBuffer}. The result
997 * is {@code true} if and only if this {@code String} represents the same
998 * sequence of characters as the specified {@code StringBuffer}. This method
999 * synchronizes on the {@code StringBuffer}.
1000 *
1001 * @param sb
1002 * The {@code StringBuffer} to compare this {@code String} against
1003 *
1004 * @return {@code true} if this {@code String} represents the same
1005 * sequence of characters as the specified {@code StringBuffer},
1006 * {@code false} otherwise
1007 *
1008 * @since 1.4
1009 */
1010 public boolean contentEquals(StringBuffer sb) {
1011 return contentEquals((CharSequence)sb);
1012 }
1013
1014 private boolean nonSyncContentEquals(AbstractStringBuilder sb) {
1015 char v1[] = value;
1016 char v2[] = sb.getValue();
1017 int n = v1.length;
1018 if (n != sb.length()) {
1019 return false;
1020 }
1021 for (int i = 0; i < n; i++) {
1022 if (v1[i] != v2[i]) {
1023 return false;
1024 }
1025 }
1026 return true;
1027 }
1028
1029 /**
1030 * Compares this string to the specified {@code CharSequence}. The
1031 * result is {@code true} if and only if this {@code String} represents the
1032 * same sequence of char values as the specified sequence. Note that if the
1033 * {@code CharSequence} is a {@code StringBuffer} then the method
1034 * synchronizes on it.
1035 *
1036 * @param cs
1037 * The sequence to compare this {@code String} against
1038 *
1039 * @return {@code true} if this {@code String} represents the same
1040 * sequence of char values as the specified sequence, {@code
1041 * false} otherwise
1042 *
1043 * @since 1.5
1044 */
1045 public boolean contentEquals(CharSequence cs) {
1046 // Argument is a StringBuffer, StringBuilder
1047 if (cs instanceof AbstractStringBuilder) {
1048 if (cs instanceof StringBuffer) {
1049 synchronized(cs) {
1050 return nonSyncContentEquals((AbstractStringBuilder)cs);
1051 }
1052 } else {
1053 return nonSyncContentEquals((AbstractStringBuilder)cs);
1054 }
1055 }
1056 // Argument is a String
1057 if (cs instanceof String) {
1058 return equals(cs);
1059 }
1060 // Argument is a generic CharSequence
1061 char v1[] = value;
1062 int n = v1.length;
1063 if (n != cs.length()) {
1064 return false;
1065 }
1066 for (int i = 0; i < n; i++) {
1067 if (v1[i] != cs.charAt(i)) {
1068 return false;
1069 }
1070 }
1071 return true;
1072 }
1073
1074 /**
1075 * Compares this {@code String} to another {@code String}, ignoring case
1076 * considerations. Two strings are considered equal ignoring case if they
1077 * are of the same length and corresponding characters in the two strings
1078 * are equal ignoring case.
1079 *
1080 * <p> Two characters {@code c1} and {@code c2} are considered the same
1081 * ignoring case if at least one of the following is true:
1082 * <ul>
1083 * <li> The two characters are the same (as compared by the
1084 * {@code ==} operator)
1085 * <li> Applying the method {@link
1086 * java.lang.Character#toUpperCase(char)} to each character
1087 * produces the same result
1088 * <li> Applying the method {@link
1089 * java.lang.Character#toLowerCase(char)} to each character
1090 * produces the same result
1091 * </ul>
1092 *
1093 * @param anotherString
1094 * The {@code String} to compare this {@code String} against
1095 *
1096 * @return {@code true} if the argument is not {@code null} and it
1097 * represents an equivalent {@code String} ignoring case; {@code
1098 * false} otherwise
1099 *
1100 * @see #equals(Object)
1101 */
1102 public boolean equalsIgnoreCase(String anotherString) {
1103 return (this == anotherString) ? true
1104 : (anotherString != null)
1105 && (anotherString.value.length == value.length)
1106 && regionMatches(true, 0, anotherString, 0, value.length);
1107 }
1108
1109 /**
1110 * Compares two strings lexicographically.
1111 * The comparison is based on the Unicode value of each character in
1112 * the strings. The character sequence represented by this
1113 * {@code String} object is compared lexicographically to the
1114 * character sequence represented by the argument string. The result is
1115 * a negative integer if this {@code String} object
1116 * lexicographically precedes the argument string. The result is a
1117 * positive integer if this {@code String} object lexicographically
1118 * follows the argument string. The result is zero if the strings
1119 * are equal; {@code compareTo} returns {@code 0} exactly when
1120 * the {@link #equals(Object)} method would return {@code true}.
1121 * <p>
1122 * This is the definition of lexicographic ordering. If two strings are
1123 * different, then either they have different characters at some index
1124 * that is a valid index for both strings, or their lengths are different,
1125 * or both. If they have different characters at one or more index
1126 * positions, let <i>k</i> be the smallest such index; then the string
1127 * whose character at position <i>k</i> has the smaller value, as
1128 * determined by using the < operator, lexicographically precedes the
1129 * other string. In this case, {@code compareTo} returns the
1130 * difference of the two character values at position {@code k} in
1131 * the two string -- that is, the value:
1132 * <blockquote><pre>
1133 * this.charAt(k)-anotherString.charAt(k)
1134 * </pre></blockquote>
1135 * If there is no index position at which they differ, then the shorter
1136 * string lexicographically precedes the longer string. In this case,
1137 * {@code compareTo} returns the difference of the lengths of the
1138 * strings -- that is, the value:
1139 * <blockquote><pre>
1140 * this.length()-anotherString.length()
1141 * </pre></blockquote>
1142 *
1143 * @param anotherString the {@code String} to be compared.
1144 * @return the value {@code 0} if the argument string is equal to
1145 * this string; a value less than {@code 0} if this string
1146 * is lexicographically less than the string argument; and a
1147 * value greater than {@code 0} if this string is
1148 * lexicographically greater than the string argument.
1149 */
1150 public int compareTo(String anotherString) {
1151 int len1 = value.length;
1152 int len2 = anotherString.value.length;
1153 int lim = Math.min(len1, len2);
1154 char v1[] = value;
1155 char v2[] = anotherString.value;
1156
1157 int k = 0;
1158 while (k < lim) {
1159 char c1 = v1[k];
1160 char c2 = v2[k];
1161 if (c1 != c2) {
1162 return c1 - c2;
1163 }
1164 k++;
1165 }
1166 return len1 - len2;
1167 }
1168
1169 /**
1170 * A Comparator that orders {@code String} objects as by
1171 * {@code compareToIgnoreCase}. This comparator is serializable.
1172 * <p>
1173 * Note that this Comparator does <em>not</em> take locale into account,
1174 * and will result in an unsatisfactory ordering for certain locales.
1175 * The java.text package provides <em>Collators</em> to allow
1176 * locale-sensitive ordering.
1177 *
1178 * @see java.text.Collator#compare(String, String)
1179 * @since 1.2
1180 */
1181 public static final Comparator<String> CASE_INSENSITIVE_ORDER
1182 = new CaseInsensitiveComparator();
1183 private static class CaseInsensitiveComparator
1184 implements Comparator<String>, java.io.Serializable {
1185 // use serialVersionUID from JDK 1.2.2 for interoperability
1186 private static final long serialVersionUID = 8575799808933029326L;
1187
1188 public int compare(String s1, String s2) {
1189 int n1 = s1.length();
1190 int n2 = s2.length();
1191 int min = Math.min(n1, n2);
1192 for (int i = 0; i < min; i++) {
1193 char c1 = s1.charAt(i);
1194 char c2 = s2.charAt(i);
1195 if (c1 != c2) {
1196 c1 = Character.toUpperCase(c1);
1197 c2 = Character.toUpperCase(c2);
1198 if (c1 != c2) {
1199 c1 = Character.toLowerCase(c1);
1200 c2 = Character.toLowerCase(c2);
1201 if (c1 != c2) {
1202 // No overflow because of numeric promotion
1203 return c1 - c2;
1204 }
1205 }
1206 }
1207 }
1208 return n1 - n2;
1209 }
1210
1211 /** Replaces the de-serialized object. */
1212 private Object readResolve() { return CASE_INSENSITIVE_ORDER; }
1213 }
1214
1215 /**
1216 * Compares two strings lexicographically, ignoring case
1217 * differences. This method returns an integer whose sign is that of
1218 * calling {@code compareTo} with normalized versions of the strings
1219 * where case differences have been eliminated by calling
1220 * {@code Character.toLowerCase(Character.toUpperCase(character))} on
1221 * each character.
1222 * <p>
1223 * Note that this method does <em>not</em> take locale into account,
1224 * and will result in an unsatisfactory ordering for certain locales.
1225 * The java.text package provides <em>collators</em> to allow
1226 * locale-sensitive ordering.
1227 *
1228 * @param str the {@code String} to be compared.
1229 * @return a negative integer, zero, or a positive integer as the
1230 * specified String is greater than, equal to, or less
1231 * than this String, ignoring case considerations.
1232 * @see java.text.Collator#compare(String, String)
1233 * @since 1.2
1234 */
1235 public int compareToIgnoreCase(String str) {
1236 return CASE_INSENSITIVE_ORDER.compare(this, str);
1237 }
1238
1239 /**
1240 * Tests if two string regions are equal.
1241 * <p>
1242 * A substring of this {@code String} object is compared to a substring
1243 * of the argument other. The result is true if these substrings
1244 * represent identical character sequences. The substring of this
1245 * {@code String} object to be compared begins at index {@code toffset}
1246 * and has length {@code len}. The substring of other to be compared
1247 * begins at index {@code ooffset} and has length {@code len}. The
1248 * result is {@code false} if and only if at least one of the following
1249 * is true:
1250 * <ul><li>{@code toffset} is negative.
1251 * <li>{@code ooffset} is negative.
1252 * <li>{@code toffset+len} is greater than the length of this
1253 * {@code String} object.
1254 * <li>{@code ooffset+len} is greater than the length of the other
1255 * argument.
1256 * <li>There is some nonnegative integer <i>k</i> less than {@code len}
1257 * such that:
1258 * {@code this.charAt(toffset + }<i>k</i>{@code ) != other.charAt(ooffset + }
1259 * <i>k</i>{@code )}
1260 * </ul>
1261 *
1262 * @param toffset the starting offset of the subregion in this string.
1263 * @param other the string argument.
1264 * @param ooffset the starting offset of the subregion in the string
1265 * argument.
1266 * @param len the number of characters to compare.
1267 * @return {@code true} if the specified subregion of this string
1268 * exactly matches the specified subregion of the string argument;
1269 * {@code false} otherwise.
1270 */
1271 public boolean regionMatches(int toffset, String other, int ooffset,
1272 int len) {
1273 char ta[] = value;
1274 int to = toffset;
1275 char pa[] = other.value;
1276 int po = ooffset;
1277 // Note: toffset, ooffset, or len might be near -1>>>1.
1278 if ((ooffset < 0) || (toffset < 0)
1279 || (toffset > (long)value.length - len)
1280 || (ooffset > (long)other.value.length - len)) {
1281 return false;
1282 }
1283 while (len-- > 0) {
1284 if (ta[to++] != pa[po++]) {
1285 return false;
1286 }
1287 }
1288 return true;
1289 }
1290
1291 /**
1292 * Tests if two string regions are equal.
1293 * <p>
1294 * A substring of this {@code String} object is compared to a substring
1295 * of the argument {@code other}. The result is {@code true} if these
1296 * substrings represent character sequences that are the same, ignoring
1297 * case if and only if {@code ignoreCase} is true. The substring of
1298 * this {@code String} object to be compared begins at index
1299 * {@code toffset} and has length {@code len}. The substring of
1300 * {@code other} to be compared begins at index {@code ooffset} and
1301 * has length {@code len}. The result is {@code false} if and only if
1302 * at least one of the following is true:
1303 * <ul><li>{@code toffset} is negative.
1304 * <li>{@code ooffset} is negative.
1305 * <li>{@code toffset+len} is greater than the length of this
1306 * {@code String} object.
1307 * <li>{@code ooffset+len} is greater than the length of the other
1308 * argument.
1309 * <li>{@code ignoreCase} is {@code false} and there is some nonnegative
1310 * integer <i>k</i> less than {@code len} such that:
1311 * <blockquote><pre>
1312 * this.charAt(toffset+k) != other.charAt(ooffset+k)
1313 * </pre></blockquote>
1314 * <li>{@code ignoreCase} is {@code true} and there is some nonnegative
1315 * integer <i>k</i> less than {@code len} such that:
1316 * <blockquote><pre>
1317 * Character.toLowerCase(this.charAt(toffset+k)) !=
1318 Character.toLowerCase(other.charAt(ooffset+k))
1319 * </pre></blockquote>
1320 * and:
1321 * <blockquote><pre>
1322 * Character.toUpperCase(this.charAt(toffset+k)) !=
1323 * Character.toUpperCase(other.charAt(ooffset+k))
1324 * </pre></blockquote>
1325 * </ul>
1326 *
1327 * @param ignoreCase if {@code true}, ignore case when comparing
1328 * characters.
1329 * @param toffset the starting offset of the subregion in this
1330 * string.
1331 * @param other the string argument.
1332 * @param ooffset the starting offset of the subregion in the string
1333 * argument.
1334 * @param len the number of characters to compare.
1335 * @return {@code true} if the specified subregion of this string
1336 * matches the specified subregion of the string argument;
1337 * {@code false} otherwise. Whether the matching is exact
1338 * or case insensitive depends on the {@code ignoreCase}
1339 * argument.
1340 */
1341 public boolean regionMatches(boolean ignoreCase, int toffset,
1342 String other, int ooffset, int len) {
1343 char ta[] = value;
1344 int to = toffset;
1345 char pa[] = other.value;
1346 int po = ooffset;
1347 // Note: toffset, ooffset, or len might be near -1>>>1.
1348 if ((ooffset < 0) || (toffset < 0)
1349 || (toffset > (long)value.length - len)
1350 || (ooffset > (long)other.value.length - len)) {
1351 return false;
1352 }
1353 while (len-- > 0) {
1354 char c1 = ta[to++];
1355 char c2 = pa[po++];
1356 if (c1 == c2) {
1357 continue;
1358 }
1359 if (ignoreCase) {
1360 // If characters don't match but case may be ignored,
1361 // try converting both characters to uppercase.
1362 // If the results match, then the comparison scan should
1363 // continue.
1364 char u1 = Character.toUpperCase(c1);
1365 char u2 = Character.toUpperCase(c2);
1366 if (u1 == u2) {
1367 continue;
1368 }
1369 // Unfortunately, conversion to uppercase does not work properly
1370 // for the Georgian alphabet, which has strange rules about case
1371 // conversion. So we need to make one last check before
1372 // exiting.
1373 if (Character.toLowerCase(u1) == Character.toLowerCase(u2)) {
1374 continue;
1375 }
1376 }
1377 return false;
1378 }
1379 return true;
1380 }
1381
1382 /**
1383 * Tests if the substring of this string beginning at the
1384 * specified index starts with the specified prefix.
1385 *
1386 * @param prefix the prefix.
1387 * @param toffset where to begin looking in this string.
1388 * @return {@code true} if the character sequence represented by the
1389 * argument is a prefix of the substring of this object starting
1390 * at index {@code toffset}; {@code false} otherwise.
1391 * The result is {@code false} if {@code toffset} is
1392 * negative or greater than the length of this
1393 * {@code String} object; otherwise the result is the same
1394 * as the result of the expression
1395 * <pre>
1396 * this.substring(toffset).startsWith(prefix)
1397 * </pre>
1398 */
1399 public boolean startsWith(String prefix, int toffset) {
1400 char ta[] = value;
1401 int to = toffset;
1402 char pa[] = prefix.value;
1403 int po = 0;
1404 int pc = prefix.value.length;
1405 // Note: toffset might be near -1>>>1.
1406 if ((toffset < 0) || (toffset > value.length - pc)) {
1407 return false;
1408 }
1409 while (--pc >= 0) {
1410 if (ta[to++] != pa[po++]) {
1411 return false;
1412 }
1413 }
1414 return true;
1415 }
1416
1417 /**
1418 * Tests if this string starts with the specified prefix.
1419 *
1420 * @param prefix the prefix.
1421 * @return {@code true} if the character sequence represented by the
1422 * argument is a prefix of the character sequence represented by
1423 * this string; {@code false} otherwise.
1424 * Note also that {@code true} will be returned if the
1425 * argument is an empty string or is equal to this
1426 * {@code String} object as determined by the
1427 * {@link #equals(Object)} method.
1428 * @since 1.0
1429 */
1430 public boolean startsWith(String prefix) {
1431 return startsWith(prefix, 0);
1432 }
1433
1434 /**
1435 * Tests if this string ends with the specified suffix.
1436 *
1437 * @param suffix the suffix.
1438 * @return {@code true} if the character sequence represented by the
1439 * argument is a suffix of the character sequence represented by
1440 * this object; {@code false} otherwise. Note that the
1441 * result will be {@code true} if the argument is the
1442 * empty string or is equal to this {@code String} object
1443 * as determined by the {@link #equals(Object)} method.
1444 */
1445 public boolean endsWith(String suffix) {
1446 return startsWith(suffix, value.length - suffix.value.length);
1447 }
1448
1449 /**
1450 * Returns a hash code for this string. The hash code for a
1451 * {@code String} object is computed as
1452 * <blockquote><pre>
1453 * s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]
1454 * </pre></blockquote>
1455 * using {@code int} arithmetic, where {@code s[i]} is the
1456 * <i>i</i>th character of the string, {@code n} is the length of
1457 * the string, and {@code ^} indicates exponentiation.
1458 * (The hash value of the empty string is zero.)
1459 *
1460 * @return a hash code value for this object.
1461 */
1462 public int hashCode() {
1463 int h = hash;
1464 if (h == 0) {
1465 for (char v : value) {
1466 h = 31 * h + v;
1467 }
1468 hash = h;
1469 }
1470 return h;
1471 }
1472
1473 /**
1474 * Returns the index within this string of the first occurrence of
1475 * the specified character. If a character with value
1476 * {@code ch} occurs in the character sequence represented by
1477 * this {@code String} object, then the index (in Unicode
1478 * code units) of the first such occurrence is returned. For
1479 * values of {@code ch} in the range from 0 to 0xFFFF
1480 * (inclusive), this is the smallest value <i>k</i> such that:
1481 * <blockquote><pre>
1482 * this.charAt(<i>k</i>) == ch
1483 * </pre></blockquote>
1484 * is true. For other values of {@code ch}, it is the
1485 * smallest value <i>k</i> such that:
1486 * <blockquote><pre>
1487 * this.codePointAt(<i>k</i>) == ch
1488 * </pre></blockquote>
1489 * is true. In either case, if no such character occurs in this
1490 * string, then {@code -1} is returned.
1491 *
1492 * @param ch a character (Unicode code point).
1493 * @return the index of the first occurrence of the character in the
1494 * character sequence represented by this object, or
1495 * {@code -1} if the character does not occur.
1496 */
1497 public int indexOf(int ch) {
1498 return indexOf(ch, 0);
1499 }
1500
1501 /**
1502 * Returns the index within this string of the first occurrence of the
1503 * specified character, starting the search at the specified index.
1504 * <p>
1505 * If a character with value {@code ch} occurs in the
1506 * character sequence represented by this {@code String}
1507 * object at an index no smaller than {@code fromIndex}, then
1508 * the index of the first such occurrence is returned. For values
1509 * of {@code ch} in the range from 0 to 0xFFFF (inclusive),
1510 * this is the smallest value <i>k</i> such that:
1511 * <blockquote><pre>
1512 * (this.charAt(<i>k</i>) == ch) {@code &&} (<i>k</i> >= fromIndex)
1513 * </pre></blockquote>
1514 * is true. For other values of {@code ch}, it is the
1515 * smallest value <i>k</i> such that:
1516 * <blockquote><pre>
1517 * (this.codePointAt(<i>k</i>) == ch) {@code &&} (<i>k</i> >= fromIndex)
1518 * </pre></blockquote>
1519 * is true. In either case, if no such character occurs in this
1520 * string at or after position {@code fromIndex}, then
1521 * {@code -1} is returned.
1522 *
1523 * <p>
1524 * There is no restriction on the value of {@code fromIndex}. If it
1525 * is negative, it has the same effect as if it were zero: this entire
1526 * string may be searched. If it is greater than the length of this
1527 * string, it has the same effect as if it were equal to the length of
1528 * this string: {@code -1} is returned.
1529 *
1530 * <p>All indices are specified in {@code char} values
1531 * (Unicode code units).
1532 *
1533 * @param ch a character (Unicode code point).
1534 * @param fromIndex the index to start the search from.
1535 * @return the index of the first occurrence of the character in the
1536 * character sequence represented by this object that is greater
1537 * than or equal to {@code fromIndex}, or {@code -1}
1538 * if the character does not occur.
1539 */
1540 public int indexOf(int ch, int fromIndex) {
1541 final int max = value.length;
1542 if (fromIndex < 0) {
1543 fromIndex = 0;
1544 } else if (fromIndex >= max) {
1545 // Note: fromIndex might be near -1>>>1.
1546 return -1;
1547 }
1548
1549 if (ch < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
1550 // handle most cases here (ch is a BMP code point or a
1551 // negative value (invalid code point))
1552 final char[] value = this.value;
1553 for (int i = fromIndex; i < max; i++) {
1554 if (value[i] == ch) {
1555 return i;
1556 }
1557 }
1558 return -1;
1559 } else {
1560 return indexOfSupplementary(ch, fromIndex);
1561 }
1562 }
1563
1564 /**
1565 * Handles (rare) calls of indexOf with a supplementary character.
1566 */
1567 private int indexOfSupplementary(int ch, int fromIndex) {
1568 if (Character.isValidCodePoint(ch)) {
1569 final char[] value = this.value;
1570 final char hi = Character.highSurrogate(ch);
1571 final char lo = Character.lowSurrogate(ch);
1572 final int max = value.length - 1;
1573 for (int i = fromIndex; i < max; i++) {
1574 if (value[i] == hi && value[i + 1] == lo) {
1575 return i;
1576 }
1577 }
1578 }
1579 return -1;
1580 }
1581
1582 /**
1583 * Returns the index within this string of the last occurrence of
1584 * the specified character. For values of {@code ch} in the
1585 * range from 0 to 0xFFFF (inclusive), the index (in Unicode code
1586 * units) returned is the largest value <i>k</i> such that:
1587 * <blockquote><pre>
1588 * this.charAt(<i>k</i>) == ch
1589 * </pre></blockquote>
1590 * is true. For other values of {@code ch}, it is the
1591 * largest value <i>k</i> such that:
1592 * <blockquote><pre>
1593 * this.codePointAt(<i>k</i>) == ch
1594 * </pre></blockquote>
1595 * is true. In either case, if no such character occurs in this
1596 * string, then {@code -1} is returned. The
1597 * {@code String} is searched backwards starting at the last
1598 * character.
1599 *
1600 * @param ch a character (Unicode code point).
1601 * @return the index of the last occurrence of the character in the
1602 * character sequence represented by this object, or
1603 * {@code -1} if the character does not occur.
1604 */
1605 public int lastIndexOf(int ch) {
1606 return lastIndexOf(ch, value.length - 1);
1607 }
1608
1609 /**
1610 * Returns the index within this string of the last occurrence of
1611 * the specified character, searching backward starting at the
1612 * specified index. For values of {@code ch} in the range
1613 * from 0 to 0xFFFF (inclusive), the index returned is the largest
1614 * value <i>k</i> such that:
1615 * <blockquote><pre>
1616 * (this.charAt(<i>k</i>) == ch) {@code &&} (<i>k</i> <= fromIndex)
1617 * </pre></blockquote>
1618 * is true. For other values of {@code ch}, it is the
1619 * largest value <i>k</i> such that:
1620 * <blockquote><pre>
1621 * (this.codePointAt(<i>k</i>) == ch) {@code &&} (<i>k</i> <= fromIndex)
1622 * </pre></blockquote>
1623 * is true. In either case, if no such character occurs in this
1624 * string at or before position {@code fromIndex}, then
1625 * {@code -1} is returned.
1626 *
1627 * <p>All indices are specified in {@code char} values
1628 * (Unicode code units).
1629 *
1630 * @param ch a character (Unicode code point).
1631 * @param fromIndex the index to start the search from. There is no
1632 * restriction on the value of {@code fromIndex}. If it is
1633 * greater than or equal to the length of this string, it has
1634 * the same effect as if it were equal to one less than the
1635 * length of this string: this entire string may be searched.
1636 * If it is negative, it has the same effect as if it were -1:
1637 * -1 is returned.
1638 * @return the index of the last occurrence of the character in the
1639 * character sequence represented by this object that is less
1640 * than or equal to {@code fromIndex}, or {@code -1}
1641 * if the character does not occur before that point.
1642 */
1643 public int lastIndexOf(int ch, int fromIndex) {
1644 if (ch < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
1645 // handle most cases here (ch is a BMP code point or a
1646 // negative value (invalid code point))
1647 final char[] value = this.value;
1648 int i = Math.min(fromIndex, value.length - 1);
1649 for (; i >= 0; i--) {
1650 if (value[i] == ch) {
1651 return i;
1652 }
1653 }
1654 return -1;
1655 } else {
1656 return lastIndexOfSupplementary(ch, fromIndex);
1657 }
1658 }
1659
1660 /**
1661 * Handles (rare) calls of lastIndexOf with a supplementary character.
1662 */
1663 private int lastIndexOfSupplementary(int ch, int fromIndex) {
1664 if (Character.isValidCodePoint(ch)) {
1665 final char[] value = this.value;
1666 char hi = Character.highSurrogate(ch);
1667 char lo = Character.lowSurrogate(ch);
1668 int i = Math.min(fromIndex, value.length - 2);
1669 for (; i >= 0; i--) {
1670 if (value[i] == hi && value[i + 1] == lo) {
1671 return i;
1672 }
1673 }
1674 }
1675 return -1;
1676 }
1677
1678 /**
1679 * Returns the index within this string of the first occurrence of the
1680 * specified substring.
1681 *
1682 * <p>The returned index is the smallest value {@code k} for which:
1683 * <pre>{@code
1684 * this.startsWith(str, k)
1685 * }</pre>
1686 * If no such value of {@code k} exists, then {@code -1} is returned.
1687 *
1688 * @param str the substring to search for.
1689 * @return the index of the first occurrence of the specified substring,
1690 * or {@code -1} if there is no such occurrence.
1691 */
1692 public int indexOf(String str) {
1693 return indexOf(str, 0);
1694 }
1695
1696 /**
1697 * Returns the index within this string of the first occurrence of the
1698 * specified substring, starting at the specified index.
1699 *
1700 * <p>The returned index is the smallest value {@code k} for which:
1701 * <pre>{@code
1702 * k >= Math.min(fromIndex, this.length()) &&
1703 * this.startsWith(str, k)
1704 * }</pre>
1705 * If no such value of {@code k} exists, then {@code -1} is returned.
1706 *
1707 * @param str the substring to search for.
1708 * @param fromIndex the index from which to start the search.
1709 * @return the index of the first occurrence of the specified substring,
1710 * starting at the specified index,
1711 * or {@code -1} if there is no such occurrence.
1712 */
1713 public int indexOf(String str, int fromIndex) {
1714 return indexOf(value, 0, value.length,
1715 str.value, 0, str.value.length, fromIndex);
1716 }
1717
1718 /**
1719 * Code shared by String and AbstractStringBuilder to do searches. The
1720 * source is the character array being searched, and the target
1721 * is the string being searched for.
1722 *
1723 * @param source the characters being searched.
1724 * @param sourceOffset offset of the source string.
1725 * @param sourceCount count of the source string.
1726 * @param target the characters being searched for.
1727 * @param fromIndex the index to begin searching from.
1728 */
1729 static int indexOf(char[] source, int sourceOffset, int sourceCount,
1730 String target, int fromIndex) {
1731 return indexOf(source, sourceOffset, sourceCount,
1732 target.value, 0, target.value.length,
1733 fromIndex);
1734 }
1735
1736 /**
1737 * Code shared by String and StringBuffer to do searches. The
1738 * source is the character array being searched, and the target
1739 * is the string being searched for.
1740 *
1741 * @param source the characters being searched.
1742 * @param sourceOffset offset of the source string.
1743 * @param sourceCount count of the source string.
1744 * @param target the characters being searched for.
1745 * @param targetOffset offset of the target string.
1746 * @param targetCount count of the target string.
1747 * @param fromIndex the index to begin searching from.
1748 */
1749 static int indexOf(char[] source, int sourceOffset, int sourceCount,
1750 char[] target, int targetOffset, int targetCount,
1751 int fromIndex) {
1752 if (fromIndex >= sourceCount) {
1753 return (targetCount == 0 ? sourceCount : -1);
1754 }
1755 if (fromIndex < 0) {
1756 fromIndex = 0;
1757 }
1758 if (targetCount == 0) {
1759 return fromIndex;
1760 }
1761
1762 char first = target[targetOffset];
1763 int max = sourceOffset + (sourceCount - targetCount);
1764
1765 for (int i = sourceOffset + fromIndex; i <= max; i++) {
1766 /* Look for first character. */
1767 if (source[i] != first) {
1768 while (++i <= max && source[i] != first);
1769 }
1770
1771 /* Found first character, now look at the rest of v2 */
1772 if (i <= max) {
1773 int j = i + 1;
1774 int end = j + targetCount - 1;
1775 for (int k = targetOffset + 1; j < end && source[j]
1776 == target[k]; j++, k++);
1777
1778 if (j == end) {
1779 /* Found whole string. */
1780 return i - sourceOffset;
1781 }
1782 }
1783 }
1784 return -1;
1785 }
1786
1787 /**
1788 * Returns the index within this string of the last occurrence of the
1789 * specified substring. The last occurrence of the empty string ""
1790 * is considered to occur at the index value {@code this.length()}.
1791 *
1792 * <p>The returned index is the largest value {@code k} for which:
1793 * <pre>{@code
1794 * this.startsWith(str, k)
1795 * }</pre>
1796 * If no such value of {@code k} exists, then {@code -1} is returned.
1797 *
1798 * @param str the substring to search for.
1799 * @return the index of the last occurrence of the specified substring,
1800 * or {@code -1} if there is no such occurrence.
1801 */
1802 public int lastIndexOf(String str) {
1803 return lastIndexOf(str, value.length);
1804 }
1805
1806 /**
1807 * Returns the index within this string of the last occurrence of the
1808 * specified substring, searching backward starting at the specified index.
1809 *
1810 * <p>The returned index is the largest value {@code k} for which:
1811 * <pre>{@code
1812 * k <= Math.min(fromIndex, this.length()) &&
1813 * this.startsWith(str, k)
1814 * }</pre>
1815 * If no such value of {@code k} exists, then {@code -1} is returned.
1816 *
1817 * @param str the substring to search for.
1818 * @param fromIndex the index to start the search from.
1819 * @return the index of the last occurrence of the specified substring,
1820 * searching backward from the specified index,
1821 * or {@code -1} if there is no such occurrence.
1822 */
1823 public int lastIndexOf(String str, int fromIndex) {
1824 return lastIndexOf(value, 0, value.length,
1825 str.value, 0, str.value.length, fromIndex);
1826 }
1827
1828 /**
1829 * Code shared by String and AbstractStringBuilder to do searches. The
1830 * source is the character array being searched, and the target
1831 * is the string being searched for.
1832 *
1833 * @param source the characters being searched.
1834 * @param sourceOffset offset of the source string.
1835 * @param sourceCount count of the source string.
1836 * @param target the characters being searched for.
1837 * @param fromIndex the index to begin searching from.
1838 */
1839 static int lastIndexOf(char[] source, int sourceOffset, int sourceCount,
1840 String target, int fromIndex) {
1841 return lastIndexOf(source, sourceOffset, sourceCount,
1842 target.value, 0, target.value.length,
1843 fromIndex);
1844 }
1845
1846 /**
1847 * Code shared by String and StringBuffer to do searches. The
1848 * source is the character array being searched, and the target
1849 * is the string being searched for.
1850 *
1851 * @param source the characters being searched.
1852 * @param sourceOffset offset of the source string.
1853 * @param sourceCount count of the source string.
1854 * @param target the characters being searched for.
1855 * @param targetOffset offset of the target string.
1856 * @param targetCount count of the target string.
1857 * @param fromIndex the index to begin searching from.
1858 */
1859 static int lastIndexOf(char[] source, int sourceOffset, int sourceCount,
1860 char[] target, int targetOffset, int targetCount,
1861 int fromIndex) {
1862 /*
1863 * Check arguments; return immediately where possible. For
1864 * consistency, don't check for null str.
1865 */
1866 int rightIndex = sourceCount - targetCount;
1867 if (fromIndex < 0) {
1868 return -1;
1869 }
1870 if (fromIndex > rightIndex) {
1871 fromIndex = rightIndex;
1872 }
1873 /* Empty string always matches. */
1874 if (targetCount == 0) {
1875 return fromIndex;
1876 }
1877
1878 int strLastIndex = targetOffset + targetCount - 1;
1879 char strLastChar = target[strLastIndex];
1880 int min = sourceOffset + targetCount - 1;
1881 int i = min + fromIndex;
1882
1883 startSearchForLastChar:
1884 while (true) {
1885 while (i >= min && source[i] != strLastChar) {
1886 i--;
1887 }
1888 if (i < min) {
1889 return -1;
1890 }
1891 int j = i - 1;
1892 int start = j - (targetCount - 1);
1893 int k = strLastIndex - 1;
1894
1895 while (j > start) {
1896 if (source[j--] != target[k--]) {
1897 i--;
1898 continue startSearchForLastChar;
1899 }
1900 }
1901 return start - sourceOffset + 1;
1902 }
1903 }
1904
1905 /**
1906 * Returns a string that is a substring of this string. The
1907 * substring begins with the character at the specified index and
1908 * extends to the end of this string. <p>
1909 * Examples:
1910 * <blockquote><pre>
1911 * "unhappy".substring(2) returns "happy"
1912 * "Harbison".substring(3) returns "bison"
1913 * "emptiness".substring(9) returns "" (an empty string)
1914 * </pre></blockquote>
1915 *
1916 * @param beginIndex the beginning index, inclusive.
1917 * @return the specified substring.
1918 * @exception IndexOutOfBoundsException if
1919 * {@code beginIndex} is negative or larger than the
1920 * length of this {@code String} object.
1921 */
1922 public String substring(int beginIndex) {
1923 if (beginIndex < 0) {
1924 throw new StringIndexOutOfBoundsException(beginIndex);
1925 }
1926 int subLen = value.length - beginIndex;
1927 if (subLen < 0) {
1928 throw new StringIndexOutOfBoundsException(subLen);
1929 }
1930 return (beginIndex == 0) ? this : new String(value, beginIndex, subLen);
1931 }
1932
1933 /**
1934 * Returns a string that is a substring of this string. The
1935 * substring begins at the specified {@code beginIndex} and
1936 * extends to the character at index {@code endIndex - 1}.
1937 * Thus the length of the substring is {@code endIndex-beginIndex}.
1938 * <p>
1939 * Examples:
1940 * <blockquote><pre>
1941 * "hamburger".substring(4, 8) returns "urge"
1942 * "smiles".substring(1, 5) returns "mile"
1943 * </pre></blockquote>
1944 *
1945 * @param beginIndex the beginning index, inclusive.
1946 * @param endIndex the ending index, exclusive.
1947 * @return the specified substring.
1948 * @exception IndexOutOfBoundsException if the
1949 * {@code beginIndex} is negative, or
1950 * {@code endIndex} is larger than the length of
1951 * this {@code String} object, or
1952 * {@code beginIndex} is larger than
1953 * {@code endIndex}.
1954 */
1955 public String substring(int beginIndex, int endIndex) {
1956 if (beginIndex < 0) {
1957 throw new StringIndexOutOfBoundsException(beginIndex);
1958 }
1959 if (endIndex > value.length) {
1960 throw new StringIndexOutOfBoundsException(endIndex);
1961 }
1962 int subLen = endIndex - beginIndex;
1963 if (subLen < 0) {
1964 throw new StringIndexOutOfBoundsException(subLen);
1965 }
1966 return ((beginIndex == 0) && (endIndex == value.length)) ? this
1967 : new String(value, beginIndex, subLen);
1968 }
1969
1970 /**
1971 * Returns a character sequence that is a subsequence of this sequence.
1972 *
1973 * <p> An invocation of this method of the form
1974 *
1975 * <blockquote><pre>
1976 * str.subSequence(begin, end)</pre></blockquote>
1977 *
1978 * behaves in exactly the same way as the invocation
1979 *
1980 * <blockquote><pre>
1981 * str.substring(begin, end)</pre></blockquote>
1982 *
1983 * @apiNote
1984 * This method is defined so that the {@code String} class can implement
1985 * the {@link CharSequence} interface.
1986 *
1987 * @param beginIndex the begin index, inclusive.
1988 * @param endIndex the end index, exclusive.
1989 * @return the specified subsequence.
1990 *
1991 * @throws IndexOutOfBoundsException
1992 * if {@code beginIndex} or {@code endIndex} is negative,
1993 * if {@code endIndex} is greater than {@code length()},
1994 * or if {@code beginIndex} is greater than {@code endIndex}
1995 *
1996 * @since 1.4
1997 * @spec JSR-51
1998 */
1999 public CharSequence subSequence(int beginIndex, int endIndex) {
2000 return this.substring(beginIndex, endIndex);
2001 }
2002
2003 /**
2004 * Concatenates the specified string to the end of this string.
2005 * <p>
2006 * If the length of the argument string is {@code 0}, then this
2007 * {@code String} object is returned. Otherwise, a
2008 * {@code String} object is returned that represents a character
2009 * sequence that is the concatenation of the character sequence
2010 * represented by this {@code String} object and the character
2011 * sequence represented by the argument string.<p>
2012 * Examples:
2013 * <blockquote><pre>
2014 * "cares".concat("s") returns "caress"
2015 * "to".concat("get").concat("her") returns "together"
2016 * </pre></blockquote>
2017 *
2018 * @param str the {@code String} that is concatenated to the end
2019 * of this {@code String}.
2020 * @return a string that represents the concatenation of this object's
2021 * characters followed by the string argument's characters.
2022 */
2023 public String concat(String str) {
2024 int otherLen = str.length();
2025 if (otherLen == 0) {
2026 return this;
2027 }
2028 int len = value.length;
2029 char buf[] = Arrays.copyOf(value, len + otherLen);
2030 str.getChars(buf, len);
2031 return new String(buf, true);
2032 }
2033
2034 /**
2035 * Returns a string resulting from replacing all occurrences of
2036 * {@code oldChar} in this string with {@code newChar}.
2037 * <p>
2038 * If the character {@code oldChar} does not occur in the
2039 * character sequence represented by this {@code String} object,
2040 * then a reference to this {@code String} object is returned.
2041 * Otherwise, a {@code String} object is returned that
2042 * represents a character sequence identical to the character sequence
2043 * represented by this {@code String} object, except that every
2044 * occurrence of {@code oldChar} is replaced by an occurrence
2045 * of {@code newChar}.
2046 * <p>
2047 * Examples:
2048 * <blockquote><pre>
2049 * "mesquite in your cellar".replace('e', 'o')
2050 * returns "mosquito in your collar"
2051 * "the war of baronets".replace('r', 'y')
2052 * returns "the way of bayonets"
2053 * "sparring with a purple porpoise".replace('p', 't')
2054 * returns "starring with a turtle tortoise"
2055 * "JonL".replace('q', 'x') returns "JonL" (no change)
2056 * </pre></blockquote>
2057 *
2058 * @param oldChar the old character.
2059 * @param newChar the new character.
2060 * @return a string derived from this string by replacing every
2061 * occurrence of {@code oldChar} with {@code newChar}.
2062 */
2063 public String replace(char oldChar, char newChar) {
2064 if (oldChar != newChar) {
2065 int len = value.length;
2066 int i = -1;
2067 char[] val = value; /* avoid getfield opcode */
2068
2069 while (++i < len) {
2070 if (val[i] == oldChar) {
2071 break;
2072 }
2073 }
2074 if (i < len) {
2075 char buf[] = new char[len];
2076 for (int j = 0; j < i; j++) {
2077 buf[j] = val[j];
2078 }
2079 while (i < len) {
2080 char c = val[i];
2081 buf[i] = (c == oldChar) ? newChar : c;
2082 i++;
2083 }
2084 return new String(buf, true);
2085 }
2086 }
2087 return this;
2088 }
2089
2090 /**
2091 * Tells whether or not this string matches the given <a
2092 * href="../util/regex/Pattern.html#sum">regular expression</a>.
2093 *
2094 * <p> An invocation of this method of the form
2095 * <i>str</i>{@code .matches(}<i>regex</i>{@code )} yields exactly the
2096 * same result as the expression
2097 *
2098 * <blockquote>
2099 * {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#matches(String,CharSequence)
2100 * matches(<i>regex</i>, <i>str</i>)}
2101 * </blockquote>
2102 *
2103 * @param regex
2104 * the regular expression to which this string is to be matched
2105 *
2106 * @return {@code true} if, and only if, this string matches the
2107 * given regular expression
2108 *
2109 * @throws PatternSyntaxException
2110 * if the regular expression's syntax is invalid
2111 *
2112 * @see java.util.regex.Pattern
2113 *
2114 * @since 1.4
2115 * @spec JSR-51
2116 */
2117 public boolean matches(String regex) {
2118 return Pattern.matches(regex, this);
2119 }
2120
2121 /**
2122 * Returns true if and only if this string contains the specified
2123 * sequence of char values.
2124 *
2125 * @param s the sequence to search for
2126 * @return true if this string contains {@code s}, false otherwise
2127 * @since 1.5
2128 */
2129 public boolean contains(CharSequence s) {
2130 return indexOf(s.toString()) >= 0;
2131 }
2132
2133 /**
2134 * Replaces the first substring of this string that matches the given <a
2135 * href="../util/regex/Pattern.html#sum">regular expression</a> with the
2136 * given replacement.
2137 *
2138 * <p> An invocation of this method of the form
2139 * <i>str</i>{@code .replaceFirst(}<i>regex</i>{@code ,} <i>repl</i>{@code )}
2140 * yields exactly the same result as the expression
2141 *
2142 * <blockquote>
2143 * <code>
2144 * {@link java.util.regex.Pattern}.{@link
2145 * java.util.regex.Pattern#compile compile}(<i>regex</i>).{@link
2146 * java.util.regex.Pattern#matcher(java.lang.CharSequence) matcher}(<i>str</i>).{@link
2147 * java.util.regex.Matcher#replaceFirst replaceFirst}(<i>repl</i>)
2148 * </code>
2149 * </blockquote>
2150 *
2151 *<p>
2152 * Note that backslashes ({@code \}) and dollar signs ({@code $}) in the
2153 * replacement string may cause the results to be different than if it were
2154 * being treated as a literal replacement string; see
2155 * {@link java.util.regex.Matcher#replaceFirst}.
2156 * Use {@link java.util.regex.Matcher#quoteReplacement} to suppress the special
2157 * meaning of these characters, if desired.
2158 *
2159 * @param regex
2160 * the regular expression to which this string is to be matched
2161 * @param replacement
2162 * the string to be substituted for the first match
2163 *
2164 * @return The resulting {@code String}
2165 *
2166 * @throws PatternSyntaxException
2167 * if the regular expression's syntax is invalid
2168 *
2169 * @see java.util.regex.Pattern
2170 *
2171 * @since 1.4
2172 * @spec JSR-51
2173 */
2174 public String replaceFirst(String regex, String replacement) {
2175 return Pattern.compile(regex).matcher(this).replaceFirst(replacement);
2176 }
2177
2178 /**
2179 * Replaces each substring of this string that matches the given <a
2180 * href="../util/regex/Pattern.html#sum">regular expression</a> with the
2181 * given replacement.
2182 *
2183 * <p> An invocation of this method of the form
2184 * <i>str</i>{@code .replaceAll(}<i>regex</i>{@code ,} <i>repl</i>{@code )}
2185 * yields exactly the same result as the expression
2186 *
2187 * <blockquote>
2188 * <code>
2189 * {@link java.util.regex.Pattern}.{@link
2190 * java.util.regex.Pattern#compile compile}(<i>regex</i>).{@link
2191 * java.util.regex.Pattern#matcher(java.lang.CharSequence) matcher}(<i>str</i>).{@link
2192 * java.util.regex.Matcher#replaceAll replaceAll}(<i>repl</i>)
2193 * </code>
2194 * </blockquote>
2195 *
2196 *<p>
2197 * Note that backslashes ({@code \}) and dollar signs ({@code $}) in the
2198 * replacement string may cause the results to be different than if it were
2199 * being treated as a literal replacement string; see
2200 * {@link java.util.regex.Matcher#replaceAll Matcher.replaceAll}.
2201 * Use {@link java.util.regex.Matcher#quoteReplacement} to suppress the special
2202 * meaning of these characters, if desired.
2203 *
2204 * @param regex
2205 * the regular expression to which this string is to be matched
2206 * @param replacement
2207 * the string to be substituted for each match
2208 *
2209 * @return The resulting {@code String}
2210 *
2211 * @throws PatternSyntaxException
2212 * if the regular expression's syntax is invalid
2213 *
2214 * @see java.util.regex.Pattern
2215 *
2216 * @since 1.4
2217 * @spec JSR-51
2218 */
2219 public String replaceAll(String regex, String replacement) {
2220 return Pattern.compile(regex).matcher(this).replaceAll(replacement);
2221 }
2222
2223 /**
2224 * Replaces each substring of this string that matches the literal target
2225 * sequence with the specified literal replacement sequence. The
2226 * replacement proceeds from the beginning of the string to the end, for
2227 * example, replacing "aa" with "b" in the string "aaa" will result in
2228 * "ba" rather than "ab".
2229 *
2230 * @param target The sequence of char values to be replaced
2231 * @param replacement The replacement sequence of char values
2232 * @return The resulting string
2233 * @since 1.5
2234 */
2235 public String replace(CharSequence target, CharSequence replacement) {
2236 return Pattern.compile(target.toString(), Pattern.LITERAL).matcher(
2237 this).replaceAll(Matcher.quoteReplacement(replacement.toString()));
2238 }
2239
2240 /**
2241 * Splits this string around matches of the given
2242 * <a href="../util/regex/Pattern.html#sum">regular expression</a>.
2243 *
2244 * <p> The array returned by this method contains each substring of this
2245 * string that is terminated by another substring that matches the given
2246 * expression or is terminated by the end of the string. The substrings in
2247 * the array are in the order in which they occur in this string. If the
2248 * expression does not match any part of the input then the resulting array
2249 * has just one element, namely this string.
2250 *
2251 * <p> When there is a positive-width match at the beginning of this
2252 * string then an empty leading substring is included at the beginning
2253 * of the resulting array. A zero-width match at the beginning however
2254 * never produces such empty leading substring.
2255 *
2256 * <p> The {@code limit} parameter controls the number of times the
2257 * pattern is applied and therefore affects the length of the resulting
2258 * array. If the limit <i>n</i> is greater than zero then the pattern
2259 * will be applied at most <i>n</i> - 1 times, the array's
2260 * length will be no greater than <i>n</i>, and the array's last entry
2261 * will contain all input beyond the last matched delimiter. If <i>n</i>
2262 * is non-positive then the pattern will be applied as many times as
2263 * possible and the array can have any length. If <i>n</i> is zero then
2264 * the pattern will be applied as many times as possible, the array can
2265 * have any length, and trailing empty strings will be discarded.
2266 *
2267 * <p> The string {@code "boo:and:foo"}, for example, yields the
2268 * following results with these parameters:
2269 *
2270 * <blockquote><table cellpadding=1 cellspacing=0 summary="Split example showing regex, limit, and result">
2271 * <tr>
2272 * <th>Regex</th>
2273 * <th>Limit</th>
2274 * <th>Result</th>
2275 * </tr>
2276 * <tr><td align=center>:</td>
2277 * <td align=center>2</td>
2278 * <td>{@code { "boo", "and:foo" }}</td></tr>
2279 * <tr><td align=center>:</td>
2280 * <td align=center>5</td>
2281 * <td>{@code { "boo", "and", "foo" }}</td></tr>
2282 * <tr><td align=center>:</td>
2283 * <td align=center>-2</td>
2284 * <td>{@code { "boo", "and", "foo" }}</td></tr>
2285 * <tr><td align=center>o</td>
2286 * <td align=center>5</td>
2287 * <td>{@code { "b", "", ":and:f", "", "" }}</td></tr>
2288 * <tr><td align=center>o</td>
2289 * <td align=center>-2</td>
2290 * <td>{@code { "b", "", ":and:f", "", "" }}</td></tr>
2291 * <tr><td align=center>o</td>
2292 * <td align=center>0</td>
2293 * <td>{@code { "b", "", ":and:f" }}</td></tr>
2294 * </table></blockquote>
2295 *
2296 * <p> An invocation of this method of the form
2297 * <i>str.</i>{@code split(}<i>regex</i>{@code ,} <i>n</i>{@code )}
2298 * yields the same result as the expression
2299 *
2300 * <blockquote>
2301 * <code>
2302 * {@link java.util.regex.Pattern}.{@link
2303 * java.util.regex.Pattern#compile compile}(<i>regex</i>).{@link
2304 * java.util.regex.Pattern#split(java.lang.CharSequence,int) split}(<i>str</i>, <i>n</i>)
2305 * </code>
2306 * </blockquote>
2307 *
2308 *
2309 * @param regex
2310 * the delimiting regular expression
2311 *
2312 * @param limit
2313 * the result threshold, as described above
2314 *
2315 * @return the array of strings computed by splitting this string
2316 * around matches of the given regular expression
2317 *
2318 * @throws PatternSyntaxException
2319 * if the regular expression's syntax is invalid
2320 *
2321 * @see java.util.regex.Pattern
2322 *
2323 * @since 1.4
2324 * @spec JSR-51
2325 */
2326 public String[] split(String regex, int limit) {
2327 /* fastpath if the regex is a
2328 (1)one-char String and this character is not one of the
2329 RegEx's meta characters ".$|()[{^?*+\\", or
2330 (2)two-char String and the first char is the backslash and
2331 the second is not the ascii digit or ascii letter.
2332 */
2333 char ch = 0;
2334 if (((regex.value.length == 1 &&
2335 ".$|()[{^?*+\\".indexOf(ch = regex.charAt(0)) == -1) ||
2336 (regex.length() == 2 &&
2337 regex.charAt(0) == '\\' &&
2338 (((ch = regex.charAt(1))-'0')|('9'-ch)) < 0 &&
2339 ((ch-'a')|('z'-ch)) < 0 &&
2340 ((ch-'A')|('Z'-ch)) < 0)) &&
2341 (ch < Character.MIN_HIGH_SURROGATE ||
2342 ch > Character.MAX_LOW_SURROGATE))
2343 {
2344 int off = 0;
2345 int next = 0;
2346 boolean limited = limit > 0;
2347 ArrayList<String> list = new ArrayList<>();
2348 while ((next = indexOf(ch, off)) != -1) {
2349 if (!limited || list.size() < limit - 1) {
2350 list.add(substring(off, next));
2351 off = next + 1;
2352 } else { // last one
2353 //assert (list.size() == limit - 1);
2354 list.add(substring(off, value.length));
2355 off = value.length;
2356 break;
2357 }
2358 }
2359 // If no match was found, return this
2360 if (off == 0)
2361 return new String[]{this};
2362
2363 // Add remaining segment
2364 if (!limited || list.size() < limit)
2365 list.add(substring(off, value.length));
2366
2367 // Construct result
2368 int resultSize = list.size();
2369 if (limit == 0) {
2370 while (resultSize > 0 && list.get(resultSize - 1).length() == 0) {
2371 resultSize--;
2372 }
2373 }
2374 String[] result = new String[resultSize];
2375 return list.subList(0, resultSize).toArray(result);
2376 }
2377 return Pattern.compile(regex).split(this, limit);
2378 }
2379
2380 /**
2381 * Splits this string around matches of the given <a
2382 * href="../util/regex/Pattern.html#sum">regular expression</a>.
2383 *
2384 * <p> This method works as if by invoking the two-argument {@link
2385 * #split(String, int) split} method with the given expression and a limit
2386 * argument of zero. Trailing empty strings are therefore not included in
2387 * the resulting array.
2388 *
2389 * <p> The string {@code "boo:and:foo"}, for example, yields the following
2390 * results with these expressions:
2391 *
2392 * <blockquote><table cellpadding=1 cellspacing=0 summary="Split examples showing regex and result">
2393 * <tr>
2394 * <th>Regex</th>
2395 * <th>Result</th>
2396 * </tr>
2397 * <tr><td align=center>:</td>
2398 * <td>{@code { "boo", "and", "foo" }}</td></tr>
2399 * <tr><td align=center>o</td>
2400 * <td>{@code { "b", "", ":and:f" }}</td></tr>
2401 * </table></blockquote>
2402 *
2403 *
2404 * @param regex
2405 * the delimiting regular expression
2406 *
2407 * @return the array of strings computed by splitting this string
2408 * around matches of the given regular expression
2409 *
2410 * @throws PatternSyntaxException
2411 * if the regular expression's syntax is invalid
2412 *
2413 * @see java.util.regex.Pattern
2414 *
2415 * @since 1.4
2416 * @spec JSR-51
2417 */
2418 public String[] split(String regex) {
2419 return split(regex, 0);
2420 }
2421
2422 /**
2423 * Returns a new String composed of copies of the
2424 * {@code CharSequence elements} joined together with a copy of
2425 * the specified {@code delimiter}.
2426 *
2427 * <blockquote>For example,
2428 * <pre>{@code
2429 * String message = String.join("-", "Java", "is", "cool");
2430 * // message returned is: "Java-is-cool"
2431 * }</pre></blockquote>
2432 *
2433 * Note that if an element is null, then {@code "null"} is added.
2434 *
2435 * @param delimiter the delimiter that separates each element
2436 * @param elements the elements to join together.
2437 *
2438 * @return a new {@code String} that is composed of the {@code elements}
2439 * separated by the {@code delimiter}
2440 *
2441 * @throws NullPointerException If {@code delimiter} or {@code elements}
2442 * is {@code null}
2443 *
2444 * @see java.util.StringJoiner
2445 * @since 1.8
2446 */
2447 public static String join(CharSequence delimiter, CharSequence... elements) {
2448 Objects.requireNonNull(delimiter);
2449 Objects.requireNonNull(elements);
2450 // Number of elements not likely worth Arrays.stream overhead.
2451 StringJoiner joiner = new StringJoiner(delimiter);
2452 for (CharSequence cs: elements) {
2453 joiner.add(cs);
2454 }
2455 return joiner.toString();
2456 }
2457
2458 /**
2459 * Returns a new {@code String} composed of copies of the
2460 * {@code CharSequence elements} joined together with a copy of the
2461 * specified {@code delimiter}.
2462 *
2463 * <blockquote>For example,
2464 * <pre>{@code
2465 * List<String> strings = new LinkedList<>();
2466 * strings.add("Java");strings.add("is");
2467 * strings.add("cool");
2468 * String message = String.join(" ", strings);
2469 * //message returned is: "Java is cool"
2470 *
2471 * Set<String> strings = new LinkedHashSet<>();
2472 * strings.add("Java"); strings.add("is");
2473 * strings.add("very"); strings.add("cool");
2474 * String message = String.join("-", strings);
2475 * //message returned is: "Java-is-very-cool"
2476 * }</pre></blockquote>
2477 *
2478 * Note that if an individual element is {@code null}, then {@code "null"} is added.
2479 *
2480 * @param delimiter a sequence of characters that is used to separate each
2481 * of the {@code elements} in the resulting {@code String}
2482 * @param elements an {@code Iterable} that will have its {@code elements}
2483 * joined together.
2484 *
2485 * @return a new {@code String} that is composed from the {@code elements}
2486 * argument
2487 *
2488 * @throws NullPointerException If {@code delimiter} or {@code elements}
2489 * is {@code null}
2490 *
2491 * @see #join(CharSequence,CharSequence...)
2492 * @see java.util.StringJoiner
2493 * @since 1.8
2494 */
2495 public static String join(CharSequence delimiter,
2496 Iterable<? extends CharSequence> elements) {
2497 Objects.requireNonNull(delimiter);
2498 Objects.requireNonNull(elements);
2499 StringJoiner joiner = new StringJoiner(delimiter);
2500 for (CharSequence cs: elements) {
2501 joiner.add(cs);
2502 }
2503 return joiner.toString();
2504 }
2505
2506 /**
2507 * Converts all of the characters in this {@code String} to lower
2508 * case using the rules of the given {@code Locale}. Case mapping is based
2509 * on the Unicode Standard version specified by the {@link java.lang.Character Character}
2510 * class. Since case mappings are not always 1:1 char mappings, the resulting
2511 * {@code String} may be a different length than the original {@code String}.
2512 * <p>
2513 * Examples of lowercase mappings are in the following table:
2514 * <table border="1" summary="Lowercase mapping examples showing language code of locale, upper case, lower case, and description">
2515 * <tr>
2516 * <th>Language Code of Locale</th>
2517 * <th>Upper Case</th>
2518 * <th>Lower Case</th>
2519 * <th>Description</th>
2520 * </tr>
2521 * <tr>
2522 * <td>tr (Turkish)</td>
2523 * <td>\u0130</td>
2524 * <td>\u0069</td>
2525 * <td>capital letter I with dot above -> small letter i</td>
2526 * </tr>
2527 * <tr>
2528 * <td>tr (Turkish)</td>
2529 * <td>\u0049</td>
2530 * <td>\u0131</td>
2531 * <td>capital letter I -> small letter dotless i </td>
2532 * </tr>
2533 * <tr>
2534 * <td>(all)</td>
2535 * <td>French Fries</td>
2536 * <td>french fries</td>
2537 * <td>lowercased all chars in String</td>
2538 * </tr>
2539 * <tr>
2540 * <td>(all)</td>
2541 * <td><img src="doc-files/capiota.gif" alt="capiota"><img src="doc-files/capchi.gif" alt="capchi">
2542 * <img src="doc-files/captheta.gif" alt="captheta"><img src="doc-files/capupsil.gif" alt="capupsil">
2543 * <img src="doc-files/capsigma.gif" alt="capsigma"></td>
2544 * <td><img src="doc-files/iota.gif" alt="iota"><img src="doc-files/chi.gif" alt="chi">
2545 * <img src="doc-files/theta.gif" alt="theta"><img src="doc-files/upsilon.gif" alt="upsilon">
2546 * <img src="doc-files/sigma1.gif" alt="sigma"></td>
2547 * <td>lowercased all chars in String</td>
2548 * </tr>
2549 * </table>
2550 *
2551 * @param locale use the case transformation rules for this locale
2552 * @return the {@code String}, converted to lowercase.
2553 * @see java.lang.String#toLowerCase()
2554 * @see java.lang.String#toUpperCase()
2555 * @see java.lang.String#toUpperCase(Locale)
2556 * @since 1.1
2557 */
2558 public String toLowerCase(Locale locale) {
2559 if (locale == null) {
2560 throw new NullPointerException();
2561 }
2562 int first;
2563 boolean hasSurr = false;
2564 final int len = value.length;
2565
2566 // Now check if there are any characters that need to be changed, or are surrogate
2567 for (first = 0 ; first < len; first++) {
2568 int cp = (int)value[first];
2569 if (Character.isSurrogate((char)cp)) {
2570 hasSurr = true;
2571 break;
2572 }
2573 if (cp != Character.toLowerCase(cp)) { // no need to check Character.ERROR
2574 break;
2575 }
2576 }
2577 if (first == len)
2578 return this;
2579 char[] result = new char[len];
2580 System.arraycopy(value, 0, result, 0, first); // Just copy the first few
2581 // lowerCase characters.
2582 String lang = locale.getLanguage();
2583 if (lang == "tr" || lang == "az" || lang == "lt") {
2584 return toLowerCaseEx(result, first, locale, true);
2585 }
2586 if (hasSurr) {
2587 return toLowerCaseEx(result, first, locale, false);
2588 }
2589 for (int i = first; i < len; i++) {
2590 int cp = (int)value[i];
2591 if (cp == '\u03A3' || // GREEK CAPITAL LETTER SIGMA
2592 Character.isSurrogate((char)cp)) {
2593 return toLowerCaseEx(result, i, locale, false);
2594 }
2595 if (cp == '\u0130') { // LATIN CAPITAL LETTER I WITH DOT ABOVE
2596 return toLowerCaseEx(result, i, locale, true);
2597 }
2598 cp = Character.toLowerCase(cp);
2599 if (!Character.isBmpCodePoint(cp)) {
2600 return toLowerCaseEx(result, i, locale, false);
2601 }
2602 result[i] = (char)cp;
2603 }
2604 return new String(result, true);
2605 }
2606
2607 private String toLowerCaseEx(char[] result, int first, Locale locale, boolean localeDependent) {
2608 int resultOffset = first;
2609 int srcCount;
2610 for (int i = first; i < value.length; i += srcCount) {
2611 int srcChar = (int)value[i];
2612 int lowerChar;
2613 char[] lowerCharArray;
2614 srcCount = 1;
2615 if (Character.isSurrogate((char)srcChar)) {
2616 srcChar = codePointAt(i);
2617 srcCount = Character.charCount(srcChar);
2618 }
2619 if (localeDependent || srcChar == '\u03A3') { // GREEK CAPITAL LETTER SIGMA
2620 lowerChar = ConditionalSpecialCasing.toLowerCaseEx(this, i, locale);
2621 } else {
2622 lowerChar = Character.toLowerCase(srcChar);
2623 }
2624 if (Character.isBmpCodePoint(lowerChar)) { // Character.ERROR is not a bmp
2625 result[resultOffset++] = (char)lowerChar;
2626 } else {
2627 if (lowerChar == Character.ERROR) {
2628 lowerCharArray = ConditionalSpecialCasing.toLowerCaseCharArray(this, i, locale);
2629 } else if (srcCount == 2) {
2630 resultOffset += Character.toChars(lowerChar, result, resultOffset);
2631 continue;
2632 } else {
2633 lowerCharArray = Character.toChars(lowerChar);
2634 }
2635 /* Grow result if needed */
2636 int mapLen = lowerCharArray.length;
2637 if (mapLen > srcCount) {
2638 char[] result2 = new char[result.length + mapLen - srcCount];
2639 System.arraycopy(result, 0, result2, 0, resultOffset);
2640 result = result2;
2641 }
2642 for (int x = 0; x < mapLen; ++x) {
2643 result[resultOffset++] = lowerCharArray[x];
2644 }
2645 }
2646 }
2647 return new String(result, 0, resultOffset);
2648 }
2649
2650 /**
2651 * Converts all of the characters in this {@code String} to lower
2652 * case using the rules of the default locale. This is equivalent to calling
2653 * {@code toLowerCase(Locale.getDefault())}.
2654 * <p>
2655 * <b>Note:</b> This method is locale sensitive, and may produce unexpected
2656 * results if used for strings that are intended to be interpreted locale
2657 * independently.
2658 * Examples are programming language identifiers, protocol keys, and HTML
2659 * tags.
2660 * For instance, {@code "TITLE".toLowerCase()} in a Turkish locale
2661 * returns {@code "t\u005Cu0131tle"}, where '\u005Cu0131' is the
2662 * LATIN SMALL LETTER DOTLESS I character.
2663 * To obtain correct results for locale insensitive strings, use
2664 * {@code toLowerCase(Locale.ROOT)}.
2665 *
2666 * @return the {@code String}, converted to lowercase.
2667 * @see java.lang.String#toLowerCase(Locale)
2668 */
2669 public String toLowerCase() {
2670 return toLowerCase(Locale.getDefault());
2671 }
2672
2673 /**
2674 * Converts all of the characters in this {@code String} to upper
2675 * case using the rules of the given {@code Locale}. Case mapping is based
2676 * on the Unicode Standard version specified by the {@link java.lang.Character Character}
2677 * class. Since case mappings are not always 1:1 char mappings, the resulting
2678 * {@code String} may be a different length than the original {@code String}.
2679 * <p>
2680 * Examples of locale-sensitive and 1:M case mappings are in the following table.
2681 *
2682 * <table border="1" summary="Examples of locale-sensitive and 1:M case mappings. Shows Language code of locale, lower case, upper case, and description.">
2683 * <tr>
2684 * <th>Language Code of Locale</th>
2685 * <th>Lower Case</th>
2686 * <th>Upper Case</th>
2687 * <th>Description</th>
2688 * </tr>
2689 * <tr>
2690 * <td>tr (Turkish)</td>
2691 * <td>\u0069</td>
2692 * <td>\u0130</td>
2693 * <td>small letter i -> capital letter I with dot above</td>
2694 * </tr>
2695 * <tr>
2696 * <td>tr (Turkish)</td>
2697 * <td>\u0131</td>
2698 * <td>\u0049</td>
2699 * <td>small letter dotless i -> capital letter I</td>
2700 * </tr>
2701 * <tr>
2702 * <td>(all)</td>
2703 * <td>\u00df</td>
2704 * <td>\u0053 \u0053</td>
2705 * <td>small letter sharp s -> two letters: SS</td>
2706 * </tr>
2707 * <tr>
2708 * <td>(all)</td>
2709 * <td>Fahrvergnügen</td>
2710 * <td>FAHRVERGNÜGEN</td>
2711 * <td></td>
2712 * </tr>
2713 * </table>
2714 * @param locale use the case transformation rules for this locale
2715 * @return the {@code String}, converted to uppercase.
2716 * @see java.lang.String#toUpperCase()
2717 * @see java.lang.String#toLowerCase()
2718 * @see java.lang.String#toLowerCase(Locale)
2719 * @since 1.1
2720 */
2721 public String toUpperCase(Locale locale) {
2722 if (locale == null) {
2723 throw new NullPointerException();
2724 }
2725 int first;
2726 boolean hasSurr = false;
2727 final int len = value.length;
2728
2729 // Now check if there are any characters that need to be changed, or are surrogate
2730 for (first = 0 ; first < len; first++ ) {
2731 int cp = (int)value[first];
2732 if (Character.isSurrogate((char)cp)) {
2733 hasSurr = true;
2734 break;
2735 }
2736 if (cp != Character.toUpperCaseEx(cp)) { // no need to check Character.ERROR
2737 break;
2738 }
2739 }
2740 if (first == len) {
2741 return this;
2742 }
2743 char[] result = new char[len];
2744 System.arraycopy(value, 0, result, 0, first); // Just copy the first few
2745 // upperCase characters.
2746 String lang = locale.getLanguage();
2747 if (lang == "tr" || lang == "az" || lang == "lt") {
2748 return toUpperCaseEx(result, first, locale, true);
2749 }
2750 if (hasSurr) {
2751 return toUpperCaseEx(result, first, locale, false);
2752 }
2753 for (int i = first; i < len; i++) {
2754 int cp = (int)value[i];
2755 if (Character.isSurrogate((char)cp)) {
2756 return toUpperCaseEx(result, i, locale, false);
2757 }
2758 cp = Character.toUpperCaseEx(cp);
2759 if (!Character.isBmpCodePoint(cp)) { // Character.ERROR is not bmp
2760 return toUpperCaseEx(result, i, locale, false);
2761 }
2762 result[i] = (char)cp;
2763 }
2764 return new String(result, true);
2765 }
2766
2767 private String toUpperCaseEx(char[] result, int first, Locale locale,
2768 boolean localeDependent) {
2769 int resultOffset = first;
2770 int srcCount;
2771 for (int i = first; i < value.length; i += srcCount) {
2772 int srcChar = (int)value[i];
2773 int upperChar;
2774 char[] upperCharArray;
2775 srcCount = 1;
2776 if (Character.isSurrogate((char)srcChar)) {
2777 srcChar = codePointAt(i);
2778 srcCount = Character.charCount(srcChar);
2779 }
2780 if (localeDependent) {
2781 upperChar = ConditionalSpecialCasing.toUpperCaseEx(this, i, locale);
2782 } else {
2783 upperChar = Character.toUpperCaseEx(srcChar);
2784 }
2785 if (Character.isBmpCodePoint(upperChar)) {
2786 result[resultOffset++] = (char)upperChar;
2787 } else {
2788 if (upperChar == Character.ERROR) {
2789 if (localeDependent) {
2790 upperCharArray =
2791 ConditionalSpecialCasing.toUpperCaseCharArray(this, i, locale);
2792 } else {
2793 upperCharArray = Character.toUpperCaseCharArray(srcChar);
2794 }
2795 } else if (srcCount == 2) {
2796 resultOffset += Character.toChars(upperChar, result, resultOffset);
2797 continue;
2798 } else {
2799 upperCharArray = Character.toChars(upperChar);
2800 }
2801 /* Grow result if needed */
2802 int mapLen = upperCharArray.length;
2803 if (mapLen > srcCount) {
2804 char[] result2 = new char[result.length + mapLen - srcCount];
2805 System.arraycopy(result, 0, result2, 0, resultOffset);
2806 result = result2;
2807 }
2808 for (int x = 0; x < mapLen; ++x) {
2809 result[resultOffset++] = upperCharArray[x];
2810 }
2811 }
2812 }
2813 return new String(result, 0, resultOffset);
2814 }
2815
2816 /**
2817 * Converts all of the characters in this {@code String} to upper
2818 * case using the rules of the default locale. This method is equivalent to
2819 * {@code toUpperCase(Locale.getDefault())}.
2820 * <p>
2821 * <b>Note:</b> This method is locale sensitive, and may produce unexpected
2822 * results if used for strings that are intended to be interpreted locale
2823 * independently.
2824 * Examples are programming language identifiers, protocol keys, and HTML
2825 * tags.
2826 * For instance, {@code "title".toUpperCase()} in a Turkish locale
2827 * returns {@code "T\u005Cu0130TLE"}, where '\u005Cu0130' is the
2828 * LATIN CAPITAL LETTER I WITH DOT ABOVE character.
2829 * To obtain correct results for locale insensitive strings, use
2830 * {@code toUpperCase(Locale.ROOT)}.
2831 *
2832 * @return the {@code String}, converted to uppercase.
2833 * @see java.lang.String#toUpperCase(Locale)
2834 */
2835 public String toUpperCase() {
2836 return toUpperCase(Locale.getDefault());
2837 }
2838
2839 /**
2840 * Returns a string whose value is this string, with any leading and trailing
2841 * whitespace removed.
2842 * <p>
2843 * If this {@code String} object represents an empty character
2844 * sequence, or the first and last characters of character sequence
2845 * represented by this {@code String} object both have codes
2846 * greater than {@code '\u005Cu0020'} (the space character), then a
2847 * reference to this {@code String} object is returned.
2848 * <p>
2849 * Otherwise, if there is no character with a code greater than
2850 * {@code '\u005Cu0020'} in the string, then a
2851 * {@code String} object representing an empty string is
2852 * returned.
2853 * <p>
2854 * Otherwise, let <i>k</i> be the index of the first character in the
2855 * string whose code is greater than {@code '\u005Cu0020'}, and let
2856 * <i>m</i> be the index of the last character in the string whose code
2857 * is greater than {@code '\u005Cu0020'}. A {@code String}
2858 * object is returned, representing the substring of this string that
2859 * begins with the character at index <i>k</i> and ends with the
2860 * character at index <i>m</i>-that is, the result of
2861 * {@code this.substring(k, m + 1)}.
2862 * <p>
2863 * This method may be used to trim whitespace (as defined above) from
2864 * the beginning and end of a string.
2865 *
2866 * @return A string whose value is this string, with any leading and trailing white
2867 * space removed, or this string if it has no leading or
2868 * trailing white space.
2869 */
2870 public String trim() {
2871 int len = value.length;
2872 int st = 0;
2873 char[] val = value; /* avoid getfield opcode */
2874
2875 while ((st < len) && (val[st] <= ' ')) {
2876 st++;
2877 }
2878 while ((st < len) && (val[len - 1] <= ' ')) {
2879 len--;
2880 }
2881 return ((st > 0) || (len < value.length)) ? substring(st, len) : this;
2882 }
2883
2884 /**
2885 * This object (which is already a string!) is itself returned.
2886 *
2887 * @return the string itself.
2888 */
2889 public String toString() {
2890 return this;
2891 }
2892
2893 /**
2894 * Converts this string to a new character array.
2895 *
2896 * @return a newly allocated character array whose length is the length
2897 * of this string and whose contents are initialized to contain
2898 * the character sequence represented by this string.
2899 */
2900 public char[] toCharArray() {
2901 // Cannot use Arrays.copyOf because of class initialization order issues
2902 char result[] = new char[value.length];
2903 System.arraycopy(value, 0, result, 0, value.length);
2904 return result;
2905 }
2906
2907 /**
2908 * Returns a formatted string using the specified format string and
2909 * arguments.
2910 *
2911 * <p> The locale always used is the one returned by {@link
2912 * java.util.Locale#getDefault() Locale.getDefault()}.
2913 *
2914 * @param format
2915 * A <a href="../util/Formatter.html#syntax">format string</a>
2916 *
2917 * @param args
2918 * Arguments referenced by the format specifiers in the format
2919 * string. If there are more arguments than format specifiers, the
2920 * extra arguments are ignored. The number of arguments is
2921 * variable and may be zero. The maximum number of arguments is
2922 * limited by the maximum dimension of a Java array as defined by
2923 * <cite>The Java™ Virtual Machine Specification</cite>.
2924 * The behaviour on a
2925 * {@code null} argument depends on the <a
2926 * href="../util/Formatter.html#syntax">conversion</a>.
2927 *
2928 * @throws java.util.IllegalFormatException
2929 * If a format string contains an illegal syntax, a format
2930 * specifier that is incompatible with the given arguments,
2931 * insufficient arguments given the format string, or other
2932 * illegal conditions. For specification of all possible
2933 * formatting errors, see the <a
2934 * href="../util/Formatter.html#detail">Details</a> section of the
2935 * formatter class specification.
2936 *
2937 * @return A formatted string
2938 *
2939 * @see java.util.Formatter
2940 * @since 1.5
2941 */
2942 public static String format(String format, Object... args) {
2943 return new Formatter().format(format, args).toString();
2944 }
2945
2946 /**
2947 * Returns a formatted string using the specified locale, format string,
2948 * and arguments.
2949 *
2950 * @param l
2951 * The {@linkplain java.util.Locale locale} to apply during
2952 * formatting. If {@code l} is {@code null} then no localization
2953 * is applied.
2954 *
2955 * @param format
2956 * A <a href="../util/Formatter.html#syntax">format string</a>
2957 *
2958 * @param args
2959 * Arguments referenced by the format specifiers in the format
2960 * string. If there are more arguments than format specifiers, the
2961 * extra arguments are ignored. The number of arguments is
2962 * variable and may be zero. The maximum number of arguments is
2963 * limited by the maximum dimension of a Java array as defined by
2964 * <cite>The Java™ Virtual Machine Specification</cite>.
2965 * The behaviour on a
2966 * {@code null} argument depends on the
2967 * <a href="../util/Formatter.html#syntax">conversion</a>.
2968 *
2969 * @throws java.util.IllegalFormatException
2970 * If a format string contains an illegal syntax, a format
2971 * specifier that is incompatible with the given arguments,
2972 * insufficient arguments given the format string, or other
2973 * illegal conditions. For specification of all possible
2974 * formatting errors, see the <a
2975 * href="../util/Formatter.html#detail">Details</a> section of the
2976 * formatter class specification
2977 *
2978 * @return A formatted string
2979 *
2980 * @see java.util.Formatter
2981 * @since 1.5
2982 */
2983 public static String format(Locale l, String format, Object... args) {
2984 return new Formatter(l).format(format, args).toString();
2985 }
2986
2987 /**
2988 * Returns the string representation of the {@code Object} argument.
2989 *
2990 * @param obj an {@code Object}.
2991 * @return if the argument is {@code null}, then a string equal to
2992 * {@code "null"}; otherwise, the value of
2993 * {@code obj.toString()} is returned.
2994 * @see java.lang.Object#toString()
2995 */
2996 public static String valueOf(Object obj) {
2997 return (obj == null) ? "null" : obj.toString();
2998 }
2999
3000 /**
3001 * Returns the string representation of the {@code char} array
3002 * argument. The contents of the character array are copied; subsequent
3003 * modification of the character array does not affect the returned
3004 * string.
3005 *
3006 * @param data the character array.
3007 * @return a {@code String} that contains the characters of the
3008 * character array.
3009 */
3010 public static String valueOf(char data[]) {
3011 return new String(data);
3012 }
3013
3014 /**
3015 * Returns the string representation of a specific subarray of the
3016 * {@code char} array argument.
3017 * <p>
3018 * The {@code offset} argument is the index of the first
3019 * character of the subarray. The {@code count} argument
3020 * specifies the length of the subarray. The contents of the subarray
3021 * are copied; subsequent modification of the character array does not
3022 * affect the returned string.
3023 *
3024 * @param data the character array.
3025 * @param offset initial offset of the subarray.
3026 * @param count length of the subarray.
3027 * @return a {@code String} that contains the characters of the
3028 * specified subarray of the character array.
3029 * @exception IndexOutOfBoundsException if {@code offset} is
3030 * negative, or {@code count} is negative, or
3031 * {@code offset+count} is larger than
3032 * {@code data.length}.
3033 */
3034 public static String valueOf(char data[], int offset, int count) {
3035 return new String(data, offset, count);
3036 }
3037
3038 /**
3039 * Equivalent to {@link #valueOf(char[], int, int)}.
3040 *
3041 * @param data the character array.
3042 * @param offset initial offset of the subarray.
3043 * @param count length of the subarray.
3044 * @return a {@code String} that contains the characters of the
3045 * specified subarray of the character array.
3046 * @exception IndexOutOfBoundsException if {@code offset} is
3047 * negative, or {@code count} is negative, or
3048 * {@code offset+count} is larger than
3049 * {@code data.length}.
3050 */
3051 public static String copyValueOf(char data[], int offset, int count) {
3052 return new String(data, offset, count);
3053 }
3054
3055 /**
3056 * Equivalent to {@link #valueOf(char[])}.
3057 *
3058 * @param data the character array.
3059 * @return a {@code String} that contains the characters of the
3060 * character array.
3061 */
3062 public static String copyValueOf(char data[]) {
3063 return new String(data);
3064 }
3065
3066 /**
3067 * Returns the string representation of the {@code boolean} argument.
3068 *
3069 * @param b a {@code boolean}.
3070 * @return if the argument is {@code true}, a string equal to
3071 * {@code "true"} is returned; otherwise, a string equal to
3072 * {@code "false"} is returned.
3073 */
3074 public static String valueOf(boolean b) {
3075 return b ? "true" : "false";
3076 }
3077
3078 /**
3079 * Returns the string representation of the {@code char}
3080 * argument.
3081 *
3082 * @param c a {@code char}.
3083 * @return a string of length {@code 1} containing
3084 * as its single character the argument {@code c}.
3085 */
3086 public static String valueOf(char c) {
3087 char data[] = {c};
3088 return new String(data, true);
3089 }
3090
3091 /**
3092 * Returns the string representation of the {@code int} argument.
3093 * <p>
3094 * The representation is exactly the one returned by the
3095 * {@code Integer.toString} method of one argument.
3096 *
3097 * @param i an {@code int}.
3098 * @return a string representation of the {@code int} argument.
3099 * @see java.lang.Integer#toString(int, int)
3100 */
3101 public static String valueOf(int i) {
3102 return Integer.toString(i);
3103 }
3104
3105 /**
3106 * Returns the string representation of the {@code long} argument.
3107 * <p>
3108 * The representation is exactly the one returned by the
3109 * {@code Long.toString} method of one argument.
3110 *
3111 * @param l a {@code long}.
3112 * @return a string representation of the {@code long} argument.
3113 * @see java.lang.Long#toString(long)
3114 */
3115 public static String valueOf(long l) {
3116 return Long.toString(l);
3117 }
3118
3119 /**
3120 * Returns the string representation of the {@code float} argument.
3121 * <p>
3122 * The representation is exactly the one returned by the
3123 * {@code Float.toString} method of one argument.
3124 *
3125 * @param f a {@code float}.
3126 * @return a string representation of the {@code float} argument.
3127 * @see java.lang.Float#toString(float)
3128 */
3129 public static String valueOf(float f) {
3130 return Float.toString(f);
3131 }
3132
3133 /**
3134 * Returns the string representation of the {@code double} argument.
3135 * <p>
3136 * The representation is exactly the one returned by the
3137 * {@code Double.toString} method of one argument.
3138 *
3139 * @param d a {@code double}.
3140 * @return a string representation of the {@code double} argument.
3141 * @see java.lang.Double#toString(double)
3142 */
3143 public static String valueOf(double d) {
3144 return Double.toString(d);
3145 }
3146
3147 /**
3148 * Returns a canonical representation for the string object.
3149 * <p>
3150 * A pool of strings, initially empty, is maintained privately by the
3151 * class {@code String}.
3152 * <p>
3153 * When the intern method is invoked, if the pool already contains a
3154 * string equal to this {@code String} object as determined by
3155 * the {@link #equals(Object)} method, then the string from the pool is
3156 * returned. Otherwise, this {@code String} object is added to the
3157 * pool and a reference to this {@code String} object is returned.
3158 * <p>
3159 * It follows that for any two strings {@code s} and {@code t},
3160 * {@code s.intern() == t.intern()} is {@code true}
3161 * if and only if {@code s.equals(t)} is {@code true}.
3162 * <p>
3163 * All literal strings and string-valued constant expressions are
3164 * interned. String literals are defined in section 3.10.5 of the
3165 * <cite>The Java™ Language Specification</cite>.
3166 *
3167 * @return a string that has the same contents as this string, but is
3168 * guaranteed to be from a pool of unique strings.
3169 */
3170 public native String intern();
3171 }