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