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.nio.ByteBuffer;
32 import java.util.ArrayList;
33 import java.util.Arrays;
34 import java.util.Comparator;
35 import java.util.Formatter;
36 import java.util.Locale;
37 import java.util.Objects;
38 import java.util.StringJoiner;
39 import java.util.regex.Matcher;
40 import java.util.regex.Pattern;
41 import java.util.regex.PatternSyntaxException;
42
43 /**
44 * The {@code String} class represents character strings. All
45 * string literals in Java programs, such as {@code "abc"}, are
46 * implemented as instances of this class.
47 * <p>
48 * Strings are constant; their values cannot be changed after they
49 * are created. String buffers support mutable strings.
50 * Because String objects are immutable they can be shared. For example:
51 * <blockquote><pre>
52 * String str = "abc";
53 * </pre></blockquote><p>
54 * is equivalent to:
55 * <blockquote><pre>
56 * char data[] = {'a', 'b', 'c'};
57 * String str = new String(data);
58 * </pre></blockquote><p>
59 * Here are some more examples of how strings can be used:
60 * <blockquote><pre>
61 * System.out.println("abc");
62 * String cde = "cde";
63 * System.out.println("abc" + cde);
64 * String c = "abc".substring(2,3);
65 * String d = cde.substring(1, 2);
66 * </pre></blockquote>
67 * <p>
68 * The class {@code String} includes methods for examining
69 * individual characters of the sequence, for comparing strings, for
70 * searching strings, for extracting substrings, and for creating a
71 * copy of a string with all characters translated to uppercase or to
72 * lowercase. Case mapping is based on the Unicode Standard version
73 * specified by the {@link java.lang.Character Character} class.
74 * <p>
75 * The Java language provides special support for the string
76 * concatenation operator ( + ), and for conversion of
77 * other objects to strings. String concatenation is implemented
78 * through the {@code StringBuilder}(or {@code StringBuffer})
79 * class and its {@code append} method.
80 * String conversions are implemented through the method
81 * {@code toString}, defined by {@code Object} and
82 * inherited by all classes in Java. For additional information on
83 * string concatenation and conversion, see Gosling, Joy, and Steele,
84 * <i>The Java Language Specification</i>.
85 *
86 * <p> Unless otherwise noted, passing a <tt>null</tt> argument to a constructor
87 * or method in this class will cause a {@link NullPointerException} to be
88 * thrown.
89 *
90 * <p>A {@code String} represents a string in the UTF-16 format
91 * in which <em>supplementary characters</em> are represented by <em>surrogate
92 * pairs</em> (see the section <a href="Character.html#unicode">Unicode
93 * Character Representations</a> in the {@code Character} class for
94 * more information).
95 * Index values refer to {@code char} code units, so a supplementary
96 * character uses two positions in a {@code String}.
97 * <p>The {@code String} class provides methods for dealing with
98 * Unicode code points (i.e., characters), in addition to those for
99 * dealing with Unicode code units (i.e., {@code char} values).
100 *
101 * @author Lee Boynton
102 * @author Arthur van Hoff
103 * @author Martin Buchholz
104 * @author Ulf Zibis
105 * @see java.lang.Object#toString()
106 * @see java.lang.StringBuffer
107 * @see java.lang.StringBuilder
108 * @see java.nio.charset.Charset
109 * @since 1.0
110 */
111
112 public final class String
113 implements java.io.Serializable, Comparable<String>, CharSequence {
114 /** The value is used for character storage. */
115 private final char value[];
116
117 /** Cache the hash code for the string */
118 private int hash; // Default to 0
119
120 /** use serialVersionUID from JDK 1.0.2 for interoperability */
121 private static final long serialVersionUID = -6849794470754667710L;
122
123 /**
124 * Class String is special cased within the Serialization Stream Protocol.
125 *
126 * A String instance is written into an ObjectOutputStream according to
127 * <a href="{@docRoot}/../platform/serialization/spec/output.html">
128 * Object Serialization Specification, Section 6.2, "Stream Elements"</a>
129 */
130 private static final ObjectStreamField[] serialPersistentFields =
131 new ObjectStreamField[0];
132
133 /**
134 * Initializes a newly created {@code String} object so that it represents
135 * an empty character sequence. Note that use of this constructor is
136 * unnecessary since Strings are immutable.
137 */
138 public String() {
139 this.value = new char[0];
140 }
141
142 /**
143 * Initializes a newly created {@code String} object so that it represents
144 * the same sequence of characters as the argument; in other words, the
145 * newly created string is a copy of the argument string. Unless an
146 * explicit copy of {@code original} is needed, use of this constructor is
147 * unnecessary since Strings are immutable.
148 *
149 * @param original
150 * A {@code String}
151 */
152 public String(String original) {
153 this.value = original.value;
154 this.hash = original.hash;
155 }
156
157 /**
158 * Allocates a new {@code String} so that it represents the sequence of
159 * characters currently contained in the character array argument. The
160 * contents of the character array are copied; subsequent modification of
161 * the character array does not affect the newly created string.
162 *
163 * @param value
164 * The initial value of the string
165 */
166 public String(char value[]) {
167 this.value = Arrays.copyOf(value, value.length);
168 }
169
170 /**
171 * Allocates a new {@code String} that contains characters from a subarray
172 * of the character array argument. The {@code offset} argument is the
173 * index of the first character of the subarray and the {@code count}
174 * argument specifies the length of the subarray. The contents of the
175 * subarray are copied; subsequent modification of the character array does
176 * not affect the newly created string.
177 *
178 * @param value
179 * Array that is the source of characters
180 *
181 * @param offset
182 * The initial offset
183 *
184 * @param count
185 * The length
186 *
187 * @throws IndexOutOfBoundsException
188 * If the {@code offset} and {@code count} arguments index
189 * characters outside the bounds of the {@code value} array
190 */
191 public String(char value[], int offset, int count) {
192 if (offset < 0) {
193 throw new StringIndexOutOfBoundsException(offset);
194 }
195 if (count < 0) {
196 throw new StringIndexOutOfBoundsException(count);
197 }
198 // Note: offset or count might be near -1>>>1.
199 if (offset > value.length - count) {
200 throw new StringIndexOutOfBoundsException(offset + count);
201 }
202 this.value = Arrays.copyOfRange(value, offset, offset+count);
203 }
204
205 /**
206 * Allocates a new {@code String} that contains characters from a subarray
207 * of the <a href="Character.html#unicode">Unicode code point</a> array
208 * argument. The {@code offset} argument is the index of the first code
209 * point of the subarray and the {@code count} argument specifies the
210 * length of the subarray. The contents of the subarray are converted to
211 * {@code char}s; subsequent modification of the {@code int} array does not
212 * affect the newly created string.
213 *
214 * @param codePoints
215 * Array that is the source of Unicode code points
216 *
217 * @param offset
218 * The initial offset
219 *
220 * @param count
221 * The length
222 *
223 * @throws IllegalArgumentException
224 * If any invalid Unicode code point is found in {@code
225 * codePoints}
226 *
227 * @throws IndexOutOfBoundsException
228 * If the {@code offset} and {@code count} arguments index
229 * characters outside the bounds of the {@code codePoints} array
230 *
231 * @since 1.5
232 */
233 public String(int[] codePoints, int offset, int count) {
234 if (offset < 0) {
235 throw new StringIndexOutOfBoundsException(offset);
236 }
237 if (count < 0) {
238 throw new StringIndexOutOfBoundsException(count);
239 }
240 // Note: offset or count might be near -1>>>1.
241 if (offset > codePoints.length - count) {
242 throw new StringIndexOutOfBoundsException(offset + count);
243 }
244
245 final int end = offset + count;
246
247 // Pass 1: Compute precise size of char[]
248 int n = count;
249 for (int i = offset; i < end; i++) {
250 int c = codePoints[i];
251 if (Character.isBmpCodePoint(c))
252 continue;
253 else if (Character.isValidCodePoint(c))
254 n++;
255 else throw new IllegalArgumentException(Integer.toString(c));
256 }
257
258 // Pass 2: Allocate and fill in char[]
259 final char[] v = new char[n];
260
261 for (int i = offset, j = 0; i < end; i++, j++) {
262 int c = codePoints[i];
263 if (Character.isBmpCodePoint(c))
264 v[j] = (char)c;
265 else
266 Character.toSurrogates(c, v, j++);
267 }
268
269 this.value = v;
270 }
271
272 /**
273 * Allocates a new {@code String} constructed from a subarray of an array
274 * of 8-bit integer values.
275 *
276 * <p> The {@code offset} argument is the index of the first byte of the
277 * subarray, and the {@code count} argument specifies the length of the
278 * subarray.
279 *
280 * <p> Each {@code byte} in the subarray is converted to a {@code char} as
281 * specified in the method above.
282 *
283 * @deprecated This method does not properly convert bytes into characters.
284 * As of JDK 1.1, the preferred way to do this is via the
285 * {@code String} constructors that take a {@link
286 * java.nio.charset.Charset}, charset name, or that use the platform's
287 * default charset.
288 *
289 * @param ascii
290 * The bytes to be converted to characters
291 *
292 * @param hibyte
293 * The top 8 bits of each 16-bit Unicode code unit
294 *
295 * @param offset
296 * The initial offset
297 * @param count
298 * The length
299 *
300 * @throws IndexOutOfBoundsException
301 * If the {@code offset} or {@code count} argument is invalid
302 *
303 * @see #String(byte[], int)
304 * @see #String(byte[], int, int, java.lang.String)
305 * @see #String(byte[], int, int, java.nio.charset.Charset)
306 * @see #String(byte[], int, int)
307 * @see #String(byte[], java.lang.String)
308 * @see #String(byte[], java.nio.charset.Charset)
309 * @see #String(byte[])
310 */
311 @Deprecated
312 public String(byte ascii[], int hibyte, int offset, int count) {
313 checkBounds(ascii, offset, count);
314 char value[] = new char[count];
315
316 if (hibyte == 0) {
317 for (int i = count; i-- > 0;) {
318 value[i] = (char)(ascii[i + offset] & 0xff);
319 }
320 } else {
321 hibyte <<= 8;
322 for (int i = count; i-- > 0;) {
323 value[i] = (char)(hibyte | (ascii[i + offset] & 0xff));
324 }
325 }
326 this.value = value;
327 }
328
329 /**
330 * Allocates a new {@code String} containing characters constructed from
331 * an array of 8-bit integer values. Each character <i>c</i>in the
332 * resulting string is constructed from the corresponding component
333 * <i>b</i> in the byte array such that:
334 *
335 * <blockquote><pre>
336 * <b><i>c</i></b> == (char)(((hibyte & 0xff) << 8)
337 * | (<b><i>b</i></b> & 0xff))
338 * </pre></blockquote>
339 *
340 * @deprecated This method does not properly convert bytes into
341 * characters. As of JDK 1.1, the preferred way to do this is via the
342 * {@code String} constructors that take a {@link
343 * java.nio.charset.Charset}, charset name, or that use the platform's
344 * default charset.
345 *
346 * @param ascii
347 * The bytes to be converted to characters
348 *
349 * @param hibyte
350 * The top 8 bits of each 16-bit Unicode code unit
351 *
352 * @see #String(byte[], int, int, java.lang.String)
353 * @see #String(byte[], int, int, java.nio.charset.Charset)
354 * @see #String(byte[], int, int)
355 * @see #String(byte[], java.lang.String)
356 * @see #String(byte[], java.nio.charset.Charset)
357 * @see #String(byte[])
358 */
359 @Deprecated
360 public String(byte ascii[], int hibyte) {
361 this(ascii, hibyte, 0, ascii.length);
362 }
363
364 /* Common private utility method used to bounds check the byte array
365 * and requested offset & length values used by the String(byte[],..)
366 * constructors.
367 */
368 private static void checkBounds(byte[] bytes, int offset, int length) {
369 if (length < 0)
370 throw new StringIndexOutOfBoundsException(length);
371 if (offset < 0)
372 throw new StringIndexOutOfBoundsException(offset);
373 if (offset > bytes.length - length)
374 throw new StringIndexOutOfBoundsException(offset + length);
375 }
376
377 /**
378 * Constructs a new {@code String} by decoding the specified subarray of
379 * bytes using the specified charset. The length of the new {@code String}
380 * is a function of the charset, and hence may not be equal to the length
381 * of the subarray.
382 *
383 * <p> The behavior of this constructor when the given bytes are not valid
384 * in the given charset is unspecified. The {@link
385 * java.nio.charset.CharsetDecoder} class should be used when more control
386 * over the decoding process is required.
387 *
388 * @param bytes
389 * The bytes to be decoded into characters
390 *
391 * @param offset
392 * The index of the first byte to decode
393 *
394 * @param length
395 * The number of bytes to decode
396
397 * @param charsetName
398 * The name of a supported {@linkplain java.nio.charset.Charset
399 * charset}
400 *
401 * @throws UnsupportedEncodingException
402 * If the named charset is not supported
403 *
404 * @throws IndexOutOfBoundsException
405 * If the {@code offset} and {@code length} arguments index
406 * characters outside the bounds of the {@code bytes} array
407 *
408 * @since 1.1
409 */
410 public String(byte bytes[], int offset, int length, String charsetName)
411 throws UnsupportedEncodingException {
412 if (charsetName == null)
413 throw new NullPointerException("charsetName");
414 checkBounds(bytes, offset, length);
415 this.value = StringCoding.decode(charsetName, bytes, offset, length);
416 }
417
418 /**
419 * Constructs a new {@code String} by decoding the specified subarray of
420 * bytes using the specified {@linkplain java.nio.charset.Charset charset}.
421 * The length of the new {@code String} is a function of the charset, and
422 * hence may not be equal to the length of the subarray.
423 *
424 * <p> This method always replaces malformed-input and unmappable-character
425 * sequences with this charset's default replacement string. The {@link
426 * java.nio.charset.CharsetDecoder} class should be used when more control
427 * over the decoding process is required.
428 *
429 * @param bytes
430 * The bytes to be decoded into characters
431 *
432 * @param offset
433 * The index of the first byte to decode
434 *
435 * @param length
436 * The number of bytes to decode
437 *
438 * @param charset
439 * The {@linkplain java.nio.charset.Charset charset} to be used to
440 * decode the {@code bytes}
441 *
442 * @throws IndexOutOfBoundsException
443 * If the {@code offset} and {@code length} arguments index
444 * characters outside the bounds of the {@code bytes} array
445 *
446 * @since 1.6
447 */
448 public String(byte bytes[], int offset, int length, Charset charset) {
449 if (charset == null)
450 throw new NullPointerException("charset");
451 checkBounds(bytes, offset, length);
452 this.value = StringCoding.decode(charset, bytes, offset, length);
453 }
454
455 /**
456 * Constructs a new {@code String} by decoding the specified
457 * {@linkplain java.nio.ByteBuffer byte buffer} using the specified
458 * {@linkplain java.nio.charset.Charset charset}.
459 * The length of the new {@code String} is a function of the charset, and
460 * hence may not be equal to the remaining number of bytes in the
461 * {@linkplain java.nio.ByteBuffer byte buffer}.
462 *
463 * <p> This method always replaces malformed-input and unmappable-character
464 * sequences with this charset's default replacement string. The {@link
465 * java.nio.charset.CharsetDecoder} class should be used when more control
466 * over the decoding process is required.
467 *
468 * <p>
469 * Bytes are read between <code>position()</code> and <code>limit()</code>
470 * of the {@link java.nio.ByteBuffer}.
471 * After the bytes have been read the <code>position()</code> will be
472 * updated.
473 *
474 * @param bytes
475 * The bytes to be decoded into characters
476 *
477 * @param charset
478 * The {@linkplain java.nio.charset.Charset charset} to be used to
479 * decode the {@code bytes}
480 *
481 * @since 1.9
482 */
483 public String(ByteBuffer bytes, Charset charset) {
484 if (charset == null)
485 throw new NullPointerException("charset");
486 this.value = StringCoding.decode(charset, bytes);
487 }
488
489 /**
490 * Constructs a new {@code String} by decoding the specified array of bytes
491 * using the specified {@linkplain java.nio.charset.Charset charset}. The
492 * length of the new {@code String} is a function of the charset, and hence
493 * may not be equal to the length of the byte array.
494 *
495 * <p> The behavior of this constructor when the given bytes are not valid
496 * in the given charset is unspecified. The {@link
497 * java.nio.charset.CharsetDecoder} class should be used when more control
498 * over the decoding process is required.
499 *
500 * @param bytes
501 * The bytes to be decoded into characters
502 *
503 * @param charsetName
504 * The name of a supported {@linkplain java.nio.charset.Charset
505 * charset}
506 *
507 * @throws UnsupportedEncodingException
508 * If the named charset is not supported
509 *
510 * @since 1.1
511 */
512 public String(byte bytes[], String charsetName)
513 throws UnsupportedEncodingException {
514 this(bytes, 0, bytes.length, charsetName);
515 }
516
517 /**
518 * Constructs a new {@code String} by decoding the specified array of
519 * bytes using the specified {@linkplain java.nio.charset.Charset charset}.
520 * The length of the new {@code String} is a function of the charset, and
521 * hence may not be equal to the length of the byte array.
522 *
523 * <p> This method always replaces malformed-input and unmappable-character
524 * sequences with this charset's default replacement string. The {@link
525 * java.nio.charset.CharsetDecoder} class should be used when more control
526 * over the decoding process is required.
527 *
528 * @param bytes
529 * The bytes to be decoded into characters
530 *
531 * @param charset
532 * The {@linkplain java.nio.charset.Charset charset} to be used to
533 * decode the {@code bytes}
534 *
535 * @since 1.6
536 */
537 public String(byte bytes[], Charset charset) {
538 this(bytes, 0, bytes.length, charset);
539 }
540
541 /**
542 * Constructs a new {@code String} by decoding the specified subarray of
543 * bytes using the platform's default charset. The length of the new
544 * {@code String} is a function of the charset, and hence may not be equal
545 * to the length of the subarray.
546 *
547 * <p> The behavior of this constructor when the given bytes are not valid
548 * in the default charset is unspecified. The {@link
549 * java.nio.charset.CharsetDecoder} class should be used when more control
550 * over the decoding process is required.
551 *
552 * @param bytes
553 * The bytes to be decoded into characters
554 *
555 * @param offset
556 * The index of the first byte to decode
557 *
558 * @param length
559 * The number of bytes to decode
560 *
561 * @throws IndexOutOfBoundsException
562 * If the {@code offset} and the {@code length} arguments index
563 * characters outside the bounds of the {@code bytes} array
564 *
565 * @since 1.1
566 */
567 public String(byte bytes[], int offset, int length) {
568 checkBounds(bytes, offset, length);
569 this.value = StringCoding.decode(bytes, offset, length);
570 }
571
572 /**
573 * Constructs a new {@code String} by decoding the specified array of bytes
574 * using the platform's default charset. The length of the new {@code
575 * String} is a function of the charset, and hence may not be equal to the
576 * length of the byte array.
577 *
578 * <p> The behavior of this constructor when the given bytes are not valid
579 * in the default charset is unspecified. The {@link
580 * java.nio.charset.CharsetDecoder} class should be used when more control
581 * over the decoding process is required.
582 *
583 * @param bytes
584 * The bytes to be decoded into characters
585 *
586 * @since 1.1
587 */
588 public String(byte bytes[]) {
589 this(bytes, 0, bytes.length);
590 }
591
592 /**
593 * Allocates a new string that contains the sequence of characters
594 * currently contained in the string buffer argument. The contents of the
595 * string buffer are copied; subsequent modification of the string buffer
596 * does not affect the newly created string.
597 *
598 * @param buffer
599 * A {@code StringBuffer}
600 */
601 public String(StringBuffer buffer) {
602 synchronized(buffer) {
603 this.value = Arrays.copyOf(buffer.getValue(), buffer.length());
604 }
605 }
606
607 /**
608 * Allocates a new string that contains the sequence of characters
609 * currently contained in the string builder argument. The contents of the
610 * string builder are copied; subsequent modification of the string builder
611 * does not affect the newly created string.
612 *
613 * <p> This constructor is provided to ease migration to {@code
614 * StringBuilder}. Obtaining a string from a string builder via the {@code
615 * toString} method is likely to run faster and is generally preferred.
616 *
617 * @param builder
618 * A {@code StringBuilder}
619 *
620 * @since 1.5
621 */
622 public String(StringBuilder builder) {
623 this.value = Arrays.copyOf(builder.getValue(), builder.length());
624 }
625
626 /*
627 * Package private constructor which shares value array for speed.
628 * this constructor is always expected to be called with share==true.
629 * a separate constructor is needed because we already have a public
630 * String(char[]) constructor that makes a copy of the given char[].
631 */
632 String(char[] value, boolean share) {
633 // assert share : "unshared not supported";
634 this.value = value;
635 }
636
637 /**
638 * Returns the length of this string.
639 * The length is equal to the number of <a href="Character.html#unicode">Unicode
640 * code units</a> in the string.
641 *
642 * @return the length of the sequence of characters represented by this
643 * object.
644 */
645 public int length() {
646 return value.length;
647 }
648
649 /**
650 * Returns {@code true} if, and only if, {@link #length()} is {@code 0}.
651 *
652 * @return {@code true} if {@link #length()} is {@code 0}, otherwise
653 * {@code false}
654 *
655 * @since 1.6
656 */
657 public boolean isEmpty() {
658 return value.length == 0;
659 }
660
661 /**
662 * Returns the {@code char} value at the
663 * specified index. An index ranges from {@code 0} to
664 * {@code length() - 1}. The first {@code char} value of the sequence
665 * is at index {@code 0}, the next at index {@code 1},
666 * and so on, as for array indexing.
667 *
668 * <p>If the {@code char} value specified by the index is a
669 * <a href="Character.html#unicode">surrogate</a>, the surrogate
670 * value is returned.
671 *
672 * @param index the index of the {@code char} value.
673 * @return the {@code char} value at the specified index of this string.
674 * The first {@code char} value is at index {@code 0}.
675 * @exception IndexOutOfBoundsException if the {@code index}
676 * argument is negative or not less than the length of this
677 * string.
678 */
679 public char charAt(int index) {
680 if ((index < 0) || (index >= value.length)) {
681 throw new StringIndexOutOfBoundsException(index);
682 }
683 return value[index];
684 }
685
686 /**
687 * Returns the character (Unicode code point) at the specified
688 * index. The index refers to {@code char} values
689 * (Unicode code units) and ranges from {@code 0} to
690 * {@link #length()}{@code - 1}.
691 *
692 * <p> If the {@code char} value specified at the given index
693 * is in the high-surrogate range, the following index is less
694 * than the length of this {@code String}, and the
695 * {@code char} value at the following index is in the
696 * low-surrogate range, then the supplementary code point
697 * corresponding to this surrogate pair is returned. Otherwise,
698 * the {@code char} value at the given index is returned.
699 *
700 * @param index the index to the {@code char} values
701 * @return the code point value of the character at the
702 * {@code index}
703 * @exception IndexOutOfBoundsException if the {@code index}
704 * argument is negative or not less than the length of this
705 * string.
706 * @since 1.5
707 */
708 public int codePointAt(int index) {
709 if ((index < 0) || (index >= value.length)) {
710 throw new StringIndexOutOfBoundsException(index);
711 }
712 return Character.codePointAtImpl(value, index, value.length);
713 }
714
715 /**
716 * Returns the character (Unicode code point) before the specified
717 * index. The index refers to {@code char} values
718 * (Unicode code units) and ranges from {@code 1} to {@link
719 * CharSequence#length() length}.
720 *
721 * <p> If the {@code char} value at {@code (index - 1)}
722 * is in the low-surrogate range, {@code (index - 2)} is not
723 * negative, and the {@code char} value at {@code (index -
724 * 2)} is in the high-surrogate range, then the
725 * supplementary code point value of the surrogate pair is
726 * returned. If the {@code char} value at {@code index -
727 * 1} is an unpaired low-surrogate or a high-surrogate, the
728 * surrogate value is returned.
729 *
730 * @param index the index following the code point that should be returned
731 * @return the Unicode code point value before the given index.
732 * @exception IndexOutOfBoundsException if the {@code index}
733 * argument is less than 1 or greater than the length
734 * of this string.
735 * @since 1.5
736 */
737 public int codePointBefore(int index) {
738 int i = index - 1;
739 if ((i < 0) || (i >= value.length)) {
740 throw new StringIndexOutOfBoundsException(index);
741 }
742 return Character.codePointBeforeImpl(value, index, 0);
743 }
744
745 /**
746 * Returns the number of Unicode code points in the specified text
747 * range of this {@code String}. The text range begins at the
748 * specified {@code beginIndex} and extends to the
749 * {@code char} at index {@code endIndex - 1}. Thus the
750 * length (in {@code char}s) of the text range is
751 * {@code endIndex-beginIndex}. Unpaired surrogates within
752 * the text range count as one code point each.
753 *
754 * @param beginIndex the index to the first {@code char} of
755 * the text range.
756 * @param endIndex the index after the last {@code char} of
757 * the text range.
758 * @return the number of Unicode code points in the specified text
759 * range
760 * @exception IndexOutOfBoundsException if the
761 * {@code beginIndex} is negative, or {@code endIndex}
762 * is larger than the length of this {@code String}, or
763 * {@code beginIndex} is larger than {@code endIndex}.
764 * @since 1.5
765 */
766 public int codePointCount(int beginIndex, int endIndex) {
767 if (beginIndex < 0 || endIndex > value.length || beginIndex > endIndex) {
768 throw new IndexOutOfBoundsException();
769 }
770 return Character.codePointCountImpl(value, beginIndex, endIndex - beginIndex);
771 }
772
773 /**
774 * Returns the index within this {@code String} that is
775 * offset from the given {@code index} by
776 * {@code codePointOffset} code points. Unpaired surrogates
777 * within the text range given by {@code index} and
778 * {@code codePointOffset} count as one code point each.
779 *
780 * @param index the index to be offset
781 * @param codePointOffset the offset in code points
782 * @return the index within this {@code String}
783 * @exception IndexOutOfBoundsException if {@code index}
784 * is negative or larger then the length of this
785 * {@code String}, or if {@code codePointOffset} is positive
786 * and the substring starting with {@code index} has fewer
787 * than {@code codePointOffset} code points,
788 * or if {@code codePointOffset} is negative and the substring
789 * before {@code index} has fewer than the absolute value
790 * of {@code codePointOffset} code points.
791 * @since 1.5
792 */
793 public int offsetByCodePoints(int index, int codePointOffset) {
794 if (index < 0 || index > value.length) {
795 throw new IndexOutOfBoundsException();
796 }
797 return Character.offsetByCodePointsImpl(value, 0, value.length,
798 index, codePointOffset);
799 }
800
801 /**
802 * Copy characters from this string into dst starting at dstBegin.
803 * This method doesn't perform any range checking.
804 */
805 void getChars(char dst[], int dstBegin) {
806 System.arraycopy(value, 0, dst, dstBegin, value.length);
807 }
808
809 /**
810 * Copies characters from this string into the destination character
811 * array.
812 * <p>
813 * The first character to be copied is at index {@code srcBegin};
814 * the last character to be copied is at index {@code srcEnd-1}
815 * (thus the total number of characters to be copied is
816 * {@code srcEnd-srcBegin}). The characters are copied into the
817 * subarray of {@code dst} starting at index {@code dstBegin}
818 * and ending at index:
819 * <blockquote><pre>
820 * dstbegin + (srcEnd-srcBegin) - 1
821 * </pre></blockquote>
822 *
823 * @param srcBegin index of the first character in the string
824 * to copy.
825 * @param srcEnd index after the last character in the string
826 * to copy.
827 * @param dst the destination array.
828 * @param dstBegin the start offset in the destination array.
829 * @exception IndexOutOfBoundsException If any of the following
830 * is true:
831 * <ul><li>{@code srcBegin} is negative.
832 * <li>{@code srcBegin} is greater than {@code srcEnd}
833 * <li>{@code srcEnd} is greater than the length of this
834 * string
835 * <li>{@code dstBegin} is negative
836 * <li>{@code dstBegin+(srcEnd-srcBegin)} is larger than
837 * {@code dst.length}</ul>
838 */
839 public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin) {
840 if (srcBegin < 0) {
841 throw new StringIndexOutOfBoundsException(srcBegin);
842 }
843 if (srcEnd > value.length) {
844 throw new StringIndexOutOfBoundsException(srcEnd);
845 }
846 if (srcBegin > srcEnd) {
847 throw new StringIndexOutOfBoundsException(srcEnd - srcBegin);
848 }
849 System.arraycopy(value, srcBegin, dst, dstBegin, srcEnd - srcBegin);
850 }
851
852 /**
853 * Copies characters from this string into the destination byte array. Each
854 * byte receives the 8 low-order bits of the corresponding character. The
855 * eight high-order bits of each character are not copied and do not
856 * participate in the transfer in any way.
857 *
858 * <p> The first character to be copied is at index {@code srcBegin}; the
859 * last character to be copied is at index {@code srcEnd-1}. The total
860 * number of characters to be copied is {@code srcEnd-srcBegin}. The
861 * characters, converted to bytes, are copied into the subarray of {@code
862 * dst} starting at index {@code dstBegin} and ending at index:
863 *
864 * <blockquote><pre>
865 * dstbegin + (srcEnd-srcBegin) - 1
866 * </pre></blockquote>
867 *
868 * @deprecated This method does not properly convert characters into
869 * bytes. As of JDK 1.1, the preferred way to do this is via the
870 * {@link #getBytes()} method, which uses the platform's default charset.
871 *
872 * @param srcBegin
873 * Index of the first character in the string to copy
874 *
875 * @param srcEnd
876 * Index after the last character in the string to copy
877 *
878 * @param dst
879 * The destination array
880 *
881 * @param dstBegin
882 * The start offset in the destination array
883 *
884 * @throws IndexOutOfBoundsException
885 * If any of the following is true:
886 * <ul>
887 * <li> {@code srcBegin} is negative
888 * <li> {@code srcBegin} is greater than {@code srcEnd}
889 * <li> {@code srcEnd} is greater than the length of this String
890 * <li> {@code dstBegin} is negative
891 * <li> {@code dstBegin+(srcEnd-srcBegin)} is larger than {@code
892 * dst.length}
893 * </ul>
894 */
895 @Deprecated
896 public void getBytes(int srcBegin, int srcEnd, byte dst[], int dstBegin) {
897 if (srcBegin < 0) {
898 throw new StringIndexOutOfBoundsException(srcBegin);
899 }
900 if (srcEnd > value.length) {
901 throw new StringIndexOutOfBoundsException(srcEnd);
902 }
903 if (srcBegin > srcEnd) {
904 throw new StringIndexOutOfBoundsException(srcEnd - srcBegin);
905 }
906 Objects.requireNonNull(dst);
907
908 int j = dstBegin;
909 int n = srcEnd;
910 int i = srcBegin;
911 char[] val = value; /* avoid getfield opcode */
912
913 while (i < n) {
914 dst[j++] = (byte)val[i++];
915 }
916 }
917
918 /**
919 * Encodes this {@code String} into a sequence of bytes using the named
920 * charset, storing the result into a new byte array.
921 *
922 * <p> The behavior of this method when this string cannot be encoded in
923 * the given charset is unspecified. The {@link
924 * java.nio.charset.CharsetEncoder} class should be used when more control
925 * over the encoding process is required.
926 *
927 * @param charsetName
928 * The name of a supported {@linkplain java.nio.charset.Charset
929 * charset}
930 *
931 * @return The resultant byte array
932 *
933 * @throws UnsupportedEncodingException
934 * If the named charset is not supported
935 *
936 * @since 1.1
937 */
938 public byte[] getBytes(String charsetName)
939 throws UnsupportedEncodingException {
940 if (charsetName == null) throw new NullPointerException();
941 return StringCoding.encode(charsetName, value, 0, value.length);
942 }
943
944 /**
945 * Encodes this {@code String} into a sequence of bytes using the given
946 * {@linkplain java.nio.charset.Charset charset}, storing the result into a
947 * new byte array.
948 *
949 * <p> This method always replaces malformed-input and unmappable-character
950 * sequences with this charset's default replacement byte array. The
951 * {@link java.nio.charset.CharsetEncoder} class should be used when more
952 * control over the encoding process is required.
953 *
954 * @param charset
955 * The {@linkplain java.nio.charset.Charset} to be used to encode
956 * the {@code String}
957 *
958 * @return The resultant byte array
959 *
960 * @since 1.6
961 */
962 public byte[] getBytes(Charset charset) {
963 Objects.requireNonNull(charset);
964 return StringCoding.encode(charset, value, 0, value.length);
965 }
966
967 /**
968 * Encodes this {@code String} into a sequence of bytes using the given
969 * {@linkplain java.nio.charset.Charset charset}, storing the result into a
970 * byte array that has been passed as an argument.
971 * <p>
972 * The number of bytes written during encoding is a function of the charset
973 * used to perform the encoding and is returned from this method. It may not
974 * be equal to the length of this
975 * String. At most <code>destBuffer.length - destOffset</code> bytes will be written.
976 *
977 * @param destBuffer
978 * The destination array
979 *
980 * @param destOffset
981 * The start offset in the destination array
982 *
983 * @param charset
984 * The {@linkplain java.nio.charset.Charset} to be used to encode
985 * the {@code String}
986 *
987 * @return the number of bytes written
988 *
989 * @since 1.9
990 */
991 public int getBytes(byte[] destBuffer, int destOffset, Charset charset) {
992 Objects.requireNonNull(destBuffer);
993 Objects.requireNonNull(charset);
994 return StringCoding.encode(charset, value, 0, value.length, destBuffer, destOffset);
995 }
996
997 /**
998 * Encodes as many characters as possible from this {@code String} into a
999 * sequence of bytes using the given
1000 * {@linkplain java.nio.charset.Charset charset}, storing the result into a
1001 * {@linkplain java.nio.ByteBuffer byte buffer} that has been passed as an argument.
1002 * <p>
1003 * The number of bytes written during encoding is a function of the charset
1004 * used to perform the encoding and is returned from this method. It may not
1005 * be equal to the length of this
1006 * String. At most <code>destBuffer.remaining()</code> bytes will be written.
1007 * <p>
1008 * The buffer's position will be advanced to reflect the characters read and
1009 * the bytes written, but its mark and limit will not be modified.
1010 *
1011 * @param destBuffer
1012 * The destination {@linkplain java.nio.ByteBuffer}
1013 *
1014 * @param charset
1015 * The {@linkplain java.nio.charset.Charset} to be used to encode
1016 * the {@code String}
1017 *
1018 * @return the number of bytes written
1019 *
1020 * @since 1.9
1021 */
1022 public int getBytes(ByteBuffer destBuffer, Charset charset) {
1023 Objects.requireNonNull(destBuffer);
1024 Objects.requireNonNull(charset);
1025 return StringCoding.encode(charset, value, 0, value.length, destBuffer);
1026 }
1027
1028 /**
1029 * Encodes this {@code String} into a sequence of bytes using the
1030 * platform's default charset, storing the result into a new byte array.
1031 *
1032 * <p> The behavior of this method when this string cannot be encoded in
1033 * the default charset is unspecified. The {@link
1034 * java.nio.charset.CharsetEncoder} class should be used when more control
1035 * over the encoding process is required.
1036 *
1037 * @return The resultant byte array
1038 *
1039 * @since 1.1
1040 */
1041 public byte[] getBytes() {
1042 return StringCoding.encode(value, 0, value.length);
1043 }
1044
1045 /**
1046 * Compares this string to the specified object. The result is {@code
1047 * true} if and only if the argument is not {@code null} and is a {@code
1048 * String} object that represents the same sequence of characters as this
1049 * object.
1050 *
1051 * @param anObject
1052 * The object to compare this {@code String} against
1053 *
1054 * @return {@code true} if the given object represents a {@code String}
1055 * equivalent to this string, {@code false} otherwise
1056 *
1057 * @see #compareTo(String)
1058 * @see #equalsIgnoreCase(String)
1059 */
1060 public boolean equals(Object anObject) {
1061 if (this == anObject) {
1062 return true;
1063 }
1064 if (anObject instanceof String) {
1065 String anotherString = (String)anObject;
1066 int n = value.length;
1067 if (n == anotherString.value.length) {
1068 char v1[] = value;
1069 char v2[] = anotherString.value;
1070 int i = 0;
1071 while (n-- != 0) {
1072 if (v1[i] != v2[i])
1073 return false;
1074 i++;
1075 }
1076 return true;
1077 }
1078 }
1079 return false;
1080 }
1081
1082 /**
1083 * Compares this string to the specified {@code StringBuffer}. The result
1084 * is {@code true} if and only if this {@code String} represents the same
1085 * sequence of characters as the specified {@code StringBuffer}. This method
1086 * synchronizes on the {@code StringBuffer}.
1087 *
1088 * @param sb
1089 * The {@code StringBuffer} to compare this {@code String} against
1090 *
1091 * @return {@code true} if this {@code String} represents the same
1092 * sequence of characters as the specified {@code StringBuffer},
1093 * {@code false} otherwise
1094 *
1095 * @since 1.4
1096 */
1097 public boolean contentEquals(StringBuffer sb) {
1098 return contentEquals((CharSequence)sb);
1099 }
1100
1101 private boolean nonSyncContentEquals(AbstractStringBuilder sb) {
1102 char v1[] = value;
1103 char v2[] = sb.getValue();
1104 int n = v1.length;
1105 if (n != sb.length()) {
1106 return false;
1107 }
1108 for (int i = 0; i < n; i++) {
1109 if (v1[i] != v2[i]) {
1110 return false;
1111 }
1112 }
1113 return true;
1114 }
1115
1116 /**
1117 * Compares this string to the specified {@code CharSequence}. The
1118 * result is {@code true} if and only if this {@code String} represents the
1119 * same sequence of char values as the specified sequence. Note that if the
1120 * {@code CharSequence} is a {@code StringBuffer} then the method
1121 * synchronizes on it.
1122 *
1123 * @param cs
1124 * The sequence to compare this {@code String} against
1125 *
1126 * @return {@code true} if this {@code String} represents the same
1127 * sequence of char values as the specified sequence, {@code
1128 * false} otherwise
1129 *
1130 * @since 1.5
1131 */
1132 public boolean contentEquals(CharSequence cs) {
1133 // Argument is a StringBuffer, StringBuilder
1134 if (cs instanceof AbstractStringBuilder) {
1135 if (cs instanceof StringBuffer) {
1136 synchronized(cs) {
1137 return nonSyncContentEquals((AbstractStringBuilder)cs);
1138 }
1139 } else {
1140 return nonSyncContentEquals((AbstractStringBuilder)cs);
1141 }
1142 }
1143 // Argument is a String
1144 if (cs instanceof String) {
1145 return equals(cs);
1146 }
1147 // Argument is a generic CharSequence
1148 char v1[] = value;
1149 int n = v1.length;
1150 if (n != cs.length()) {
1151 return false;
1152 }
1153 for (int i = 0; i < n; i++) {
1154 if (v1[i] != cs.charAt(i)) {
1155 return false;
1156 }
1157 }
1158 return true;
1159 }
1160
1161 /**
1162 * Compares this {@code String} to another {@code String}, ignoring case
1163 * considerations. Two strings are considered equal ignoring case if they
1164 * are of the same length and corresponding characters in the two strings
1165 * are equal ignoring case.
1166 *
1167 * <p> Two characters {@code c1} and {@code c2} are considered the same
1168 * ignoring case if at least one of the following is true:
1169 * <ul>
1170 * <li> The two characters are the same (as compared by the
1171 * {@code ==} operator)
1172 * <li> Applying the method {@link
1173 * java.lang.Character#toUpperCase(char)} to each character
1174 * produces the same result
1175 * <li> Applying the method {@link
1176 * java.lang.Character#toLowerCase(char)} to each character
1177 * produces the same result
1178 * </ul>
1179 *
1180 * @param anotherString
1181 * The {@code String} to compare this {@code String} against
1182 *
1183 * @return {@code true} if the argument is not {@code null} and it
1184 * represents an equivalent {@code String} ignoring case; {@code
1185 * false} otherwise
1186 *
1187 * @see #equals(Object)
1188 */
1189 public boolean equalsIgnoreCase(String anotherString) {
1190 return (this == anotherString) ? true
1191 : (anotherString != null)
1192 && (anotherString.value.length == value.length)
1193 && regionMatches(true, 0, anotherString, 0, value.length);
1194 }
1195
1196 /**
1197 * Compares two strings lexicographically.
1198 * The comparison is based on the Unicode value of each character in
1199 * the strings. The character sequence represented by this
1200 * {@code String} object is compared lexicographically to the
1201 * character sequence represented by the argument string. The result is
1202 * a negative integer if this {@code String} object
1203 * lexicographically precedes the argument string. The result is a
1204 * positive integer if this {@code String} object lexicographically
1205 * follows the argument string. The result is zero if the strings
1206 * are equal; {@code compareTo} returns {@code 0} exactly when
1207 * the {@link #equals(Object)} method would return {@code true}.
1208 * <p>
1209 * This is the definition of lexicographic ordering. If two strings are
1210 * different, then either they have different characters at some index
1211 * that is a valid index for both strings, or their lengths are different,
1212 * or both. If they have different characters at one or more index
1213 * positions, let <i>k</i> be the smallest such index; then the string
1214 * whose character at position <i>k</i> has the smaller value, as
1215 * determined by using the < operator, lexicographically precedes the
1216 * other string. In this case, {@code compareTo} returns the
1217 * difference of the two character values at position {@code k} in
1218 * the two string -- that is, the value:
1219 * <blockquote><pre>
1220 * this.charAt(k)-anotherString.charAt(k)
1221 * </pre></blockquote>
1222 * If there is no index position at which they differ, then the shorter
1223 * string lexicographically precedes the longer string. In this case,
1224 * {@code compareTo} returns the difference of the lengths of the
1225 * strings -- that is, the value:
1226 * <blockquote><pre>
1227 * this.length()-anotherString.length()
1228 * </pre></blockquote>
1229 *
1230 * @param anotherString the {@code String} to be compared.
1231 * @return the value {@code 0} if the argument string is equal to
1232 * this string; a value less than {@code 0} if this string
1233 * is lexicographically less than the string argument; and a
1234 * value greater than {@code 0} if this string is
1235 * lexicographically greater than the string argument.
1236 */
1237 public int compareTo(String anotherString) {
1238 int len1 = value.length;
1239 int len2 = anotherString.value.length;
1240 int lim = Math.min(len1, len2);
1241 char v1[] = value;
1242 char v2[] = anotherString.value;
1243
1244 int k = 0;
1245 while (k < lim) {
1246 char c1 = v1[k];
1247 char c2 = v2[k];
1248 if (c1 != c2) {
1249 return c1 - c2;
1250 }
1251 k++;
1252 }
1253 return len1 - len2;
1254 }
1255
1256 /**
1257 * A Comparator that orders {@code String} objects as by
1258 * {@code compareToIgnoreCase}. This comparator is serializable.
1259 * <p>
1260 * Note that this Comparator does <em>not</em> take locale into account,
1261 * and will result in an unsatisfactory ordering for certain locales.
1262 * The java.text package provides <em>Collators</em> to allow
1263 * locale-sensitive ordering.
1264 *
1265 * @see java.text.Collator#compare(String, String)
1266 * @since 1.2
1267 */
1268 public static final Comparator<String> CASE_INSENSITIVE_ORDER
1269 = new CaseInsensitiveComparator();
1270 private static class CaseInsensitiveComparator
1271 implements Comparator<String>, java.io.Serializable {
1272 // use serialVersionUID from JDK 1.2.2 for interoperability
1273 private static final long serialVersionUID = 8575799808933029326L;
1274
1275 public int compare(String s1, String s2) {
1276 int n1 = s1.length();
1277 int n2 = s2.length();
1278 int min = Math.min(n1, n2);
1279 for (int i = 0; i < min; i++) {
1280 char c1 = s1.charAt(i);
1281 char c2 = s2.charAt(i);
1282 if (c1 != c2) {
1283 c1 = Character.toUpperCase(c1);
1284 c2 = Character.toUpperCase(c2);
1285 if (c1 != c2) {
1286 c1 = Character.toLowerCase(c1);
1287 c2 = Character.toLowerCase(c2);
1288 if (c1 != c2) {
1289 // No overflow because of numeric promotion
1290 return c1 - c2;
1291 }
1292 }
1293 }
1294 }
1295 return n1 - n2;
1296 }
1297
1298 /** Replaces the de-serialized object. */
1299 private Object readResolve() { return CASE_INSENSITIVE_ORDER; }
1300 }
1301
1302 /**
1303 * Compares two strings lexicographically, ignoring case
1304 * differences. This method returns an integer whose sign is that of
1305 * calling {@code compareTo} with normalized versions of the strings
1306 * where case differences have been eliminated by calling
1307 * {@code Character.toLowerCase(Character.toUpperCase(character))} on
1308 * each character.
1309 * <p>
1310 * Note that this method does <em>not</em> take locale into account,
1311 * and will result in an unsatisfactory ordering for certain locales.
1312 * The java.text package provides <em>collators</em> to allow
1313 * locale-sensitive ordering.
1314 *
1315 * @param str the {@code String} to be compared.
1316 * @return a negative integer, zero, or a positive integer as the
1317 * specified String is greater than, equal to, or less
1318 * than this String, ignoring case considerations.
1319 * @see java.text.Collator#compare(String, String)
1320 * @since 1.2
1321 */
1322 public int compareToIgnoreCase(String str) {
1323 return CASE_INSENSITIVE_ORDER.compare(this, str);
1324 }
1325
1326 /**
1327 * Tests if two string regions are equal.
1328 * <p>
1329 * A substring of this {@code String} object is compared to a substring
1330 * of the argument other. The result is true if these substrings
1331 * represent identical character sequences. The substring of this
1332 * {@code String} object to be compared begins at index {@code toffset}
1333 * and has length {@code len}. The substring of other to be compared
1334 * begins at index {@code ooffset} and has length {@code len}. The
1335 * result is {@code false} if and only if at least one of the following
1336 * is true:
1337 * <ul><li>{@code toffset} is negative.
1338 * <li>{@code ooffset} is negative.
1339 * <li>{@code toffset+len} is greater than the length of this
1340 * {@code String} object.
1341 * <li>{@code ooffset+len} is greater than the length of the other
1342 * argument.
1343 * <li>There is some nonnegative integer <i>k</i> less than {@code len}
1344 * such that:
1345 * {@code this.charAt(toffset + }<i>k</i>{@code ) != other.charAt(ooffset + }
1346 * <i>k</i>{@code )}
1347 * </ul>
1348 *
1349 * @param toffset the starting offset of the subregion in this string.
1350 * @param other the string argument.
1351 * @param ooffset the starting offset of the subregion in the string
1352 * argument.
1353 * @param len the number of characters to compare.
1354 * @return {@code true} if the specified subregion of this string
1355 * exactly matches the specified subregion of the string argument;
1356 * {@code false} otherwise.
1357 */
1358 public boolean regionMatches(int toffset, String other, int ooffset,
1359 int len) {
1360 char ta[] = value;
1361 int to = toffset;
1362 char pa[] = other.value;
1363 int po = ooffset;
1364 // Note: toffset, ooffset, or len might be near -1>>>1.
1365 if ((ooffset < 0) || (toffset < 0)
1366 || (toffset > (long)value.length - len)
1367 || (ooffset > (long)other.value.length - len)) {
1368 return false;
1369 }
1370 while (len-- > 0) {
1371 if (ta[to++] != pa[po++]) {
1372 return false;
1373 }
1374 }
1375 return true;
1376 }
1377
1378 /**
1379 * Tests if two string regions are equal.
1380 * <p>
1381 * A substring of this {@code String} object is compared to a substring
1382 * of the argument {@code other}. The result is {@code true} if these
1383 * substrings represent character sequences that are the same, ignoring
1384 * case if and only if {@code ignoreCase} is true. The substring of
1385 * this {@code String} object to be compared begins at index
1386 * {@code toffset} and has length {@code len}. The substring of
1387 * {@code other} to be compared begins at index {@code ooffset} and
1388 * has length {@code len}. The result is {@code false} if and only if
1389 * at least one of the following is true:
1390 * <ul><li>{@code toffset} is negative.
1391 * <li>{@code ooffset} is negative.
1392 * <li>{@code toffset+len} is greater than the length of this
1393 * {@code String} object.
1394 * <li>{@code ooffset+len} is greater than the length of the other
1395 * argument.
1396 * <li>{@code ignoreCase} is {@code false} and there is some nonnegative
1397 * integer <i>k</i> less than {@code len} such that:
1398 * <blockquote><pre>
1399 * this.charAt(toffset+k) != other.charAt(ooffset+k)
1400 * </pre></blockquote>
1401 * <li>{@code ignoreCase} is {@code true} and there is some nonnegative
1402 * integer <i>k</i> less than {@code len} such that:
1403 * <blockquote><pre>
1404 * Character.toLowerCase(this.charAt(toffset+k)) !=
1405 Character.toLowerCase(other.charAt(ooffset+k))
1406 * </pre></blockquote>
1407 * and:
1408 * <blockquote><pre>
1409 * Character.toUpperCase(this.charAt(toffset+k)) !=
1410 * Character.toUpperCase(other.charAt(ooffset+k))
1411 * </pre></blockquote>
1412 * </ul>
1413 *
1414 * @param ignoreCase if {@code true}, ignore case when comparing
1415 * characters.
1416 * @param toffset the starting offset of the subregion in this
1417 * string.
1418 * @param other the string argument.
1419 * @param ooffset the starting offset of the subregion in the string
1420 * argument.
1421 * @param len the number of characters to compare.
1422 * @return {@code true} if the specified subregion of this string
1423 * matches the specified subregion of the string argument;
1424 * {@code false} otherwise. Whether the matching is exact
1425 * or case insensitive depends on the {@code ignoreCase}
1426 * argument.
1427 */
1428 public boolean regionMatches(boolean ignoreCase, int toffset,
1429 String other, int ooffset, int len) {
1430 char ta[] = value;
1431 int to = toffset;
1432 char pa[] = other.value;
1433 int po = ooffset;
1434 // Note: toffset, ooffset, or len might be near -1>>>1.
1435 if ((ooffset < 0) || (toffset < 0)
1436 || (toffset > (long)value.length - len)
1437 || (ooffset > (long)other.value.length - len)) {
1438 return false;
1439 }
1440 while (len-- > 0) {
1441 char c1 = ta[to++];
1442 char c2 = pa[po++];
1443 if (c1 == c2) {
1444 continue;
1445 }
1446 if (ignoreCase) {
1447 // If characters don't match but case may be ignored,
1448 // try converting both characters to uppercase.
1449 // If the results match, then the comparison scan should
1450 // continue.
1451 char u1 = Character.toUpperCase(c1);
1452 char u2 = Character.toUpperCase(c2);
1453 if (u1 == u2) {
1454 continue;
1455 }
1456 // Unfortunately, conversion to uppercase does not work properly
1457 // for the Georgian alphabet, which has strange rules about case
1458 // conversion. So we need to make one last check before
1459 // exiting.
1460 if (Character.toLowerCase(u1) == Character.toLowerCase(u2)) {
1461 continue;
1462 }
1463 }
1464 return false;
1465 }
1466 return true;
1467 }
1468
1469 /**
1470 * Tests if the substring of this string beginning at the
1471 * specified index starts with the specified prefix.
1472 *
1473 * @param prefix the prefix.
1474 * @param toffset where to begin looking in this string.
1475 * @return {@code true} if the character sequence represented by the
1476 * argument is a prefix of the substring of this object starting
1477 * at index {@code toffset}; {@code false} otherwise.
1478 * The result is {@code false} if {@code toffset} is
1479 * negative or greater than the length of this
1480 * {@code String} object; otherwise the result is the same
1481 * as the result of the expression
1482 * <pre>
1483 * this.substring(toffset).startsWith(prefix)
1484 * </pre>
1485 */
1486 public boolean startsWith(String prefix, int toffset) {
1487 char ta[] = value;
1488 int to = toffset;
1489 char pa[] = prefix.value;
1490 int po = 0;
1491 int pc = prefix.value.length;
1492 // Note: toffset might be near -1>>>1.
1493 if ((toffset < 0) || (toffset > value.length - pc)) {
1494 return false;
1495 }
1496 while (--pc >= 0) {
1497 if (ta[to++] != pa[po++]) {
1498 return false;
1499 }
1500 }
1501 return true;
1502 }
1503
1504 /**
1505 * Tests if this string starts with the specified prefix.
1506 *
1507 * @param prefix the prefix.
1508 * @return {@code true} if the character sequence represented by the
1509 * argument is a prefix of the character sequence represented by
1510 * this string; {@code false} otherwise.
1511 * Note also that {@code true} will be returned if the
1512 * argument is an empty string or is equal to this
1513 * {@code String} object as determined by the
1514 * {@link #equals(Object)} method.
1515 * @since 1.0
1516 */
1517 public boolean startsWith(String prefix) {
1518 return startsWith(prefix, 0);
1519 }
1520
1521 /**
1522 * Tests if this string ends with the specified suffix.
1523 *
1524 * @param suffix the suffix.
1525 * @return {@code true} if the character sequence represented by the
1526 * argument is a suffix of the character sequence represented by
1527 * this object; {@code false} otherwise. Note that the
1528 * result will be {@code true} if the argument is the
1529 * empty string or is equal to this {@code String} object
1530 * as determined by the {@link #equals(Object)} method.
1531 */
1532 public boolean endsWith(String suffix) {
1533 return startsWith(suffix, value.length - suffix.value.length);
1534 }
1535
1536 /**
1537 * Returns a hash code for this string. The hash code for a
1538 * {@code String} object is computed as
1539 * <blockquote><pre>
1540 * s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]
1541 * </pre></blockquote>
1542 * using {@code int} arithmetic, where {@code s[i]} is the
1543 * <i>i</i>th character of the string, {@code n} is the length of
1544 * the string, and {@code ^} indicates exponentiation.
1545 * (The hash value of the empty string is zero.)
1546 *
1547 * @return a hash code value for this object.
1548 */
1549 public int hashCode() {
1550 int h = hash;
1551 if (h == 0) {
1552 for (char v : value) {
1553 h = 31 * h + v;
1554 }
1555 hash = h;
1556 }
1557 return h;
1558 }
1559
1560 /**
1561 * Returns the index within this string of the first occurrence of
1562 * the specified character. If a character with value
1563 * {@code ch} occurs in the character sequence represented by
1564 * this {@code String} object, then the index (in Unicode
1565 * code units) of the first such occurrence is returned. For
1566 * values of {@code ch} in the range from 0 to 0xFFFF
1567 * (inclusive), this is the smallest value <i>k</i> such that:
1568 * <blockquote><pre>
1569 * this.charAt(<i>k</i>) == ch
1570 * </pre></blockquote>
1571 * is true. For other values of {@code ch}, it is the
1572 * smallest value <i>k</i> such that:
1573 * <blockquote><pre>
1574 * this.codePointAt(<i>k</i>) == ch
1575 * </pre></blockquote>
1576 * is true. In either case, if no such character occurs in this
1577 * string, then {@code -1} is returned.
1578 *
1579 * @param ch a character (Unicode code point).
1580 * @return the index of the first occurrence of the character in the
1581 * character sequence represented by this object, or
1582 * {@code -1} if the character does not occur.
1583 */
1584 public int indexOf(int ch) {
1585 return indexOf(ch, 0);
1586 }
1587
1588 /**
1589 * Returns the index within this string of the first occurrence of the
1590 * specified character, starting the search at the specified index.
1591 * <p>
1592 * If a character with value {@code ch} occurs in the
1593 * character sequence represented by this {@code String}
1594 * object at an index no smaller than {@code fromIndex}, then
1595 * the index of the first such occurrence is returned. For values
1596 * of {@code ch} in the range from 0 to 0xFFFF (inclusive),
1597 * this is the smallest value <i>k</i> such that:
1598 * <blockquote><pre>
1599 * (this.charAt(<i>k</i>) == ch) {@code &&} (<i>k</i> >= fromIndex)
1600 * </pre></blockquote>
1601 * is true. For other values of {@code ch}, it is the
1602 * smallest value <i>k</i> such that:
1603 * <blockquote><pre>
1604 * (this.codePointAt(<i>k</i>) == ch) {@code &&} (<i>k</i> >= fromIndex)
1605 * </pre></blockquote>
1606 * is true. In either case, if no such character occurs in this
1607 * string at or after position {@code fromIndex}, then
1608 * {@code -1} is returned.
1609 *
1610 * <p>
1611 * There is no restriction on the value of {@code fromIndex}. If it
1612 * is negative, it has the same effect as if it were zero: this entire
1613 * string may be searched. If it is greater than the length of this
1614 * string, it has the same effect as if it were equal to the length of
1615 * this string: {@code -1} is returned.
1616 *
1617 * <p>All indices are specified in {@code char} values
1618 * (Unicode code units).
1619 *
1620 * @param ch a character (Unicode code point).
1621 * @param fromIndex the index to start the search from.
1622 * @return the index of the first occurrence of the character in the
1623 * character sequence represented by this object that is greater
1624 * than or equal to {@code fromIndex}, or {@code -1}
1625 * if the character does not occur.
1626 */
1627 public int indexOf(int ch, int fromIndex) {
1628 final int max = value.length;
1629 if (fromIndex < 0) {
1630 fromIndex = 0;
1631 } else if (fromIndex >= max) {
1632 // Note: fromIndex might be near -1>>>1.
1633 return -1;
1634 }
1635
1636 if (ch < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
1637 // handle most cases here (ch is a BMP code point or a
1638 // negative value (invalid code point))
1639 final char[] value = this.value;
1640 for (int i = fromIndex; i < max; i++) {
1641 if (value[i] == ch) {
1642 return i;
1643 }
1644 }
1645 return -1;
1646 } else {
1647 return indexOfSupplementary(ch, fromIndex);
1648 }
1649 }
1650
1651 /**
1652 * Handles (rare) calls of indexOf with a supplementary character.
1653 */
1654 private int indexOfSupplementary(int ch, int fromIndex) {
1655 if (Character.isValidCodePoint(ch)) {
1656 final char[] value = this.value;
1657 final char hi = Character.highSurrogate(ch);
1658 final char lo = Character.lowSurrogate(ch);
1659 final int max = value.length - 1;
1660 for (int i = fromIndex; i < max; i++) {
1661 if (value[i] == hi && value[i + 1] == lo) {
1662 return i;
1663 }
1664 }
1665 }
1666 return -1;
1667 }
1668
1669 /**
1670 * Returns the index within this string of the last occurrence of
1671 * the specified character. For values of {@code ch} in the
1672 * range from 0 to 0xFFFF (inclusive), the index (in Unicode code
1673 * units) returned is the largest value <i>k</i> such that:
1674 * <blockquote><pre>
1675 * this.charAt(<i>k</i>) == ch
1676 * </pre></blockquote>
1677 * is true. For other values of {@code ch}, it is the
1678 * largest value <i>k</i> such that:
1679 * <blockquote><pre>
1680 * this.codePointAt(<i>k</i>) == ch
1681 * </pre></blockquote>
1682 * is true. In either case, if no such character occurs in this
1683 * string, then {@code -1} is returned. The
1684 * {@code String} is searched backwards starting at the last
1685 * character.
1686 *
1687 * @param ch a character (Unicode code point).
1688 * @return the index of the last occurrence of the character in the
1689 * character sequence represented by this object, or
1690 * {@code -1} if the character does not occur.
1691 */
1692 public int lastIndexOf(int ch) {
1693 return lastIndexOf(ch, value.length - 1);
1694 }
1695
1696 /**
1697 * Returns the index within this string of the last occurrence of
1698 * the specified character, searching backward starting at the
1699 * specified index. For values of {@code ch} in the range
1700 * from 0 to 0xFFFF (inclusive), the index returned is the largest
1701 * value <i>k</i> such that:
1702 * <blockquote><pre>
1703 * (this.charAt(<i>k</i>) == ch) {@code &&} (<i>k</i> <= fromIndex)
1704 * </pre></blockquote>
1705 * is true. For other values of {@code ch}, it is the
1706 * largest value <i>k</i> such that:
1707 * <blockquote><pre>
1708 * (this.codePointAt(<i>k</i>) == ch) {@code &&} (<i>k</i> <= fromIndex)
1709 * </pre></blockquote>
1710 * is true. In either case, if no such character occurs in this
1711 * string at or before position {@code fromIndex}, then
1712 * {@code -1} is returned.
1713 *
1714 * <p>All indices are specified in {@code char} values
1715 * (Unicode code units).
1716 *
1717 * @param ch a character (Unicode code point).
1718 * @param fromIndex the index to start the search from. There is no
1719 * restriction on the value of {@code fromIndex}. If it is
1720 * greater than or equal to the length of this string, it has
1721 * the same effect as if it were equal to one less than the
1722 * length of this string: this entire string may be searched.
1723 * If it is negative, it has the same effect as if it were -1:
1724 * -1 is returned.
1725 * @return the index of the last occurrence of the character in the
1726 * character sequence represented by this object that is less
1727 * than or equal to {@code fromIndex}, or {@code -1}
1728 * if the character does not occur before that point.
1729 */
1730 public int lastIndexOf(int ch, int fromIndex) {
1731 if (ch < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
1732 // handle most cases here (ch is a BMP code point or a
1733 // negative value (invalid code point))
1734 final char[] value = this.value;
1735 int i = Math.min(fromIndex, value.length - 1);
1736 for (; i >= 0; i--) {
1737 if (value[i] == ch) {
1738 return i;
1739 }
1740 }
1741 return -1;
1742 } else {
1743 return lastIndexOfSupplementary(ch, fromIndex);
1744 }
1745 }
1746
1747 /**
1748 * Handles (rare) calls of lastIndexOf with a supplementary character.
1749 */
1750 private int lastIndexOfSupplementary(int ch, int fromIndex) {
1751 if (Character.isValidCodePoint(ch)) {
1752 final char[] value = this.value;
1753 char hi = Character.highSurrogate(ch);
1754 char lo = Character.lowSurrogate(ch);
1755 int i = Math.min(fromIndex, value.length - 2);
1756 for (; i >= 0; i--) {
1757 if (value[i] == hi && value[i + 1] == lo) {
1758 return i;
1759 }
1760 }
1761 }
1762 return -1;
1763 }
1764
1765 /**
1766 * Returns the index within this string of the first occurrence of the
1767 * specified substring.
1768 *
1769 * <p>The returned index is the smallest value {@code k} for which:
1770 * <pre>{@code
1771 * this.startsWith(str, k)
1772 * }</pre>
1773 * If no such value of {@code k} exists, then {@code -1} is returned.
1774 *
1775 * @param str the substring to search for.
1776 * @return the index of the first occurrence of the specified substring,
1777 * or {@code -1} if there is no such occurrence.
1778 */
1779 public int indexOf(String str) {
1780 return indexOf(str, 0);
1781 }
1782
1783 /**
1784 * Returns the index within this string of the first occurrence of the
1785 * specified substring, starting at the specified index.
1786 *
1787 * <p>The returned index is the smallest value {@code k} for which:
1788 * <pre>{@code
1789 * k >= Math.min(fromIndex, this.length()) &&
1790 * this.startsWith(str, k)
1791 * }</pre>
1792 * If no such value of {@code k} exists, then {@code -1} is returned.
1793 *
1794 * @param str the substring to search for.
1795 * @param fromIndex the index from which to start the search.
1796 * @return the index of the first occurrence of the specified substring,
1797 * starting at the specified index,
1798 * or {@code -1} if there is no such occurrence.
1799 */
1800 public int indexOf(String str, int fromIndex) {
1801 return indexOf(value, 0, value.length,
1802 str.value, 0, str.value.length, fromIndex);
1803 }
1804
1805 /**
1806 * Code shared by String and AbstractStringBuilder to do searches. The
1807 * source is the character array being searched, and the target
1808 * is the string being searched for.
1809 *
1810 * @param source the characters being searched.
1811 * @param sourceOffset offset of the source string.
1812 * @param sourceCount count of the source string.
1813 * @param target the characters being searched for.
1814 * @param fromIndex the index to begin searching from.
1815 */
1816 static int indexOf(char[] source, int sourceOffset, int sourceCount,
1817 String target, int fromIndex) {
1818 return indexOf(source, sourceOffset, sourceCount,
1819 target.value, 0, target.value.length,
1820 fromIndex);
1821 }
1822
1823 /**
1824 * Code shared by String and StringBuffer to do searches. The
1825 * source is the character array being searched, and the target
1826 * is the string being searched for.
1827 *
1828 * @param source the characters being searched.
1829 * @param sourceOffset offset of the source string.
1830 * @param sourceCount count of the source string.
1831 * @param target the characters being searched for.
1832 * @param targetOffset offset of the target string.
1833 * @param targetCount count of the target string.
1834 * @param fromIndex the index to begin searching from.
1835 */
1836 static int indexOf(char[] source, int sourceOffset, int sourceCount,
1837 char[] target, int targetOffset, int targetCount,
1838 int fromIndex) {
1839 if (fromIndex >= sourceCount) {
1840 return (targetCount == 0 ? sourceCount : -1);
1841 }
1842 if (fromIndex < 0) {
1843 fromIndex = 0;
1844 }
1845 if (targetCount == 0) {
1846 return fromIndex;
1847 }
1848
1849 char first = target[targetOffset];
1850 int max = sourceOffset + (sourceCount - targetCount);
1851
1852 for (int i = sourceOffset + fromIndex; i <= max; i++) {
1853 /* Look for first character. */
1854 if (source[i] != first) {
1855 while (++i <= max && source[i] != first);
1856 }
1857
1858 /* Found first character, now look at the rest of v2 */
1859 if (i <= max) {
1860 int j = i + 1;
1861 int end = j + targetCount - 1;
1862 for (int k = targetOffset + 1; j < end && source[j]
1863 == target[k]; j++, k++);
1864
1865 if (j == end) {
1866 /* Found whole string. */
1867 return i - sourceOffset;
1868 }
1869 }
1870 }
1871 return -1;
1872 }
1873
1874 /**
1875 * Returns the index within this string of the last occurrence of the
1876 * specified substring. The last occurrence of the empty string ""
1877 * is considered to occur at the index value {@code this.length()}.
1878 *
1879 * <p>The returned index is the largest value {@code k} for which:
1880 * <pre>{@code
1881 * this.startsWith(str, k)
1882 * }</pre>
1883 * If no such value of {@code k} exists, then {@code -1} is returned.
1884 *
1885 * @param str the substring to search for.
1886 * @return the index of the last occurrence of the specified substring,
1887 * or {@code -1} if there is no such occurrence.
1888 */
1889 public int lastIndexOf(String str) {
1890 return lastIndexOf(str, value.length);
1891 }
1892
1893 /**
1894 * Returns the index within this string of the last occurrence of the
1895 * specified substring, searching backward starting at the specified index.
1896 *
1897 * <p>The returned index is the largest value {@code k} for which:
1898 * <pre>{@code
1899 * k <= Math.min(fromIndex, this.length()) &&
1900 * this.startsWith(str, k)
1901 * }</pre>
1902 * If no such value of {@code k} exists, then {@code -1} is returned.
1903 *
1904 * @param str the substring to search for.
1905 * @param fromIndex the index to start the search from.
1906 * @return the index of the last occurrence of the specified substring,
1907 * searching backward from the specified index,
1908 * or {@code -1} if there is no such occurrence.
1909 */
1910 public int lastIndexOf(String str, int fromIndex) {
1911 return lastIndexOf(value, 0, value.length,
1912 str.value, 0, str.value.length, fromIndex);
1913 }
1914
1915 /**
1916 * Code shared by String and AbstractStringBuilder to do searches. The
1917 * source is the character array being searched, and the target
1918 * is the string being searched for.
1919 *
1920 * @param source the characters being searched.
1921 * @param sourceOffset offset of the source string.
1922 * @param sourceCount count of the source string.
1923 * @param target the characters being searched for.
1924 * @param fromIndex the index to begin searching from.
1925 */
1926 static int lastIndexOf(char[] source, int sourceOffset, int sourceCount,
1927 String target, int fromIndex) {
1928 return lastIndexOf(source, sourceOffset, sourceCount,
1929 target.value, 0, target.value.length,
1930 fromIndex);
1931 }
1932
1933 /**
1934 * Code shared by String and StringBuffer to do searches. The
1935 * source is the character array being searched, and the target
1936 * is the string being searched for.
1937 *
1938 * @param source the characters being searched.
1939 * @param sourceOffset offset of the source string.
1940 * @param sourceCount count of the source string.
1941 * @param target the characters being searched for.
1942 * @param targetOffset offset of the target string.
1943 * @param targetCount count of the target string.
1944 * @param fromIndex the index to begin searching from.
1945 */
1946 static int lastIndexOf(char[] source, int sourceOffset, int sourceCount,
1947 char[] target, int targetOffset, int targetCount,
1948 int fromIndex) {
1949 /*
1950 * Check arguments; return immediately where possible. For
1951 * consistency, don't check for null str.
1952 */
1953 int rightIndex = sourceCount - targetCount;
1954 if (fromIndex < 0) {
1955 return -1;
1956 }
1957 if (fromIndex > rightIndex) {
1958 fromIndex = rightIndex;
1959 }
1960 /* Empty string always matches. */
1961 if (targetCount == 0) {
1962 return fromIndex;
1963 }
1964
1965 int strLastIndex = targetOffset + targetCount - 1;
1966 char strLastChar = target[strLastIndex];
1967 int min = sourceOffset + targetCount - 1;
1968 int i = min + fromIndex;
1969
1970 startSearchForLastChar:
1971 while (true) {
1972 while (i >= min && source[i] != strLastChar) {
1973 i--;
1974 }
1975 if (i < min) {
1976 return -1;
1977 }
1978 int j = i - 1;
1979 int start = j - (targetCount - 1);
1980 int k = strLastIndex - 1;
1981
1982 while (j > start) {
1983 if (source[j--] != target[k--]) {
1984 i--;
1985 continue startSearchForLastChar;
1986 }
1987 }
1988 return start - sourceOffset + 1;
1989 }
1990 }
1991
1992 /**
1993 * Returns a string that is a substring of this string. The
1994 * substring begins with the character at the specified index and
1995 * extends to the end of this string. <p>
1996 * Examples:
1997 * <blockquote><pre>
1998 * "unhappy".substring(2) returns "happy"
1999 * "Harbison".substring(3) returns "bison"
2000 * "emptiness".substring(9) returns "" (an empty string)
2001 * </pre></blockquote>
2002 *
2003 * @param beginIndex the beginning index, inclusive.
2004 * @return the specified substring.
2005 * @exception IndexOutOfBoundsException if
2006 * {@code beginIndex} is negative or larger than the
2007 * length of this {@code String} object.
2008 */
2009 public String substring(int beginIndex) {
2010 if (beginIndex < 0) {
2011 throw new StringIndexOutOfBoundsException(beginIndex);
2012 }
2013 int subLen = value.length - beginIndex;
2014 if (subLen < 0) {
2015 throw new StringIndexOutOfBoundsException(subLen);
2016 }
2017 return (beginIndex == 0) ? this : new String(value, beginIndex, subLen);
2018 }
2019
2020 /**
2021 * Returns a string that is a substring of this string. The
2022 * substring begins at the specified {@code beginIndex} and
2023 * extends to the character at index {@code endIndex - 1}.
2024 * Thus the length of the substring is {@code endIndex-beginIndex}.
2025 * <p>
2026 * Examples:
2027 * <blockquote><pre>
2028 * "hamburger".substring(4, 8) returns "urge"
2029 * "smiles".substring(1, 5) returns "mile"
2030 * </pre></blockquote>
2031 *
2032 * @param beginIndex the beginning index, inclusive.
2033 * @param endIndex the ending index, exclusive.
2034 * @return the specified substring.
2035 * @exception IndexOutOfBoundsException if the
2036 * {@code beginIndex} is negative, or
2037 * {@code endIndex} is larger than the length of
2038 * this {@code String} object, or
2039 * {@code beginIndex} is larger than
2040 * {@code endIndex}.
2041 */
2042 public String substring(int beginIndex, int endIndex) {
2043 if (beginIndex < 0) {
2044 throw new StringIndexOutOfBoundsException(beginIndex);
2045 }
2046 if (endIndex > value.length) {
2047 throw new StringIndexOutOfBoundsException(endIndex);
2048 }
2049 int subLen = endIndex - beginIndex;
2050 if (subLen < 0) {
2051 throw new StringIndexOutOfBoundsException(subLen);
2052 }
2053 return ((beginIndex == 0) && (endIndex == value.length)) ? this
2054 : new String(value, beginIndex, subLen);
2055 }
2056
2057 /**
2058 * Returns a character sequence that is a subsequence of this sequence.
2059 *
2060 * <p> An invocation of this method of the form
2061 *
2062 * <blockquote><pre>
2063 * str.subSequence(begin, end)</pre></blockquote>
2064 *
2065 * behaves in exactly the same way as the invocation
2066 *
2067 * <blockquote><pre>
2068 * str.substring(begin, end)</pre></blockquote>
2069 *
2070 * @apiNote
2071 * This method is defined so that the {@code String} class can implement
2072 * the {@link CharSequence} interface.
2073 *
2074 * @param beginIndex the begin index, inclusive.
2075 * @param endIndex the end index, exclusive.
2076 * @return the specified subsequence.
2077 *
2078 * @throws IndexOutOfBoundsException
2079 * if {@code beginIndex} or {@code endIndex} is negative,
2080 * if {@code endIndex} is greater than {@code length()},
2081 * or if {@code beginIndex} is greater than {@code endIndex}
2082 *
2083 * @since 1.4
2084 * @spec JSR-51
2085 */
2086 public CharSequence subSequence(int beginIndex, int endIndex) {
2087 return this.substring(beginIndex, endIndex);
2088 }
2089
2090 /**
2091 * Concatenates the specified string to the end of this string.
2092 * <p>
2093 * If the length of the argument string is {@code 0}, then this
2094 * {@code String} object is returned. Otherwise, a
2095 * {@code String} object is returned that represents a character
2096 * sequence that is the concatenation of the character sequence
2097 * represented by this {@code String} object and the character
2098 * sequence represented by the argument string.<p>
2099 * Examples:
2100 * <blockquote><pre>
2101 * "cares".concat("s") returns "caress"
2102 * "to".concat("get").concat("her") returns "together"
2103 * </pre></blockquote>
2104 *
2105 * @param str the {@code String} that is concatenated to the end
2106 * of this {@code String}.
2107 * @return a string that represents the concatenation of this object's
2108 * characters followed by the string argument's characters.
2109 */
2110 public String concat(String str) {
2111 int otherLen = str.length();
2112 if (otherLen == 0) {
2113 return this;
2114 }
2115 int len = value.length;
2116 char buf[] = Arrays.copyOf(value, len + otherLen);
2117 str.getChars(buf, len);
2118 return new String(buf, true);
2119 }
2120
2121 /**
2122 * Returns a string resulting from replacing all occurrences of
2123 * {@code oldChar} in this string with {@code newChar}.
2124 * <p>
2125 * If the character {@code oldChar} does not occur in the
2126 * character sequence represented by this {@code String} object,
2127 * then a reference to this {@code String} object is returned.
2128 * Otherwise, a {@code String} object is returned that
2129 * represents a character sequence identical to the character sequence
2130 * represented by this {@code String} object, except that every
2131 * occurrence of {@code oldChar} is replaced by an occurrence
2132 * of {@code newChar}.
2133 * <p>
2134 * Examples:
2135 * <blockquote><pre>
2136 * "mesquite in your cellar".replace('e', 'o')
2137 * returns "mosquito in your collar"
2138 * "the war of baronets".replace('r', 'y')
2139 * returns "the way of bayonets"
2140 * "sparring with a purple porpoise".replace('p', 't')
2141 * returns "starring with a turtle tortoise"
2142 * "JonL".replace('q', 'x') returns "JonL" (no change)
2143 * </pre></blockquote>
2144 *
2145 * @param oldChar the old character.
2146 * @param newChar the new character.
2147 * @return a string derived from this string by replacing every
2148 * occurrence of {@code oldChar} with {@code newChar}.
2149 */
2150 public String replace(char oldChar, char newChar) {
2151 if (oldChar != newChar) {
2152 int len = value.length;
2153 int i = -1;
2154 char[] val = value; /* avoid getfield opcode */
2155
2156 while (++i < len) {
2157 if (val[i] == oldChar) {
2158 break;
2159 }
2160 }
2161 if (i < len) {
2162 char buf[] = new char[len];
2163 for (int j = 0; j < i; j++) {
2164 buf[j] = val[j];
2165 }
2166 while (i < len) {
2167 char c = val[i];
2168 buf[i] = (c == oldChar) ? newChar : c;
2169 i++;
2170 }
2171 return new String(buf, true);
2172 }
2173 }
2174 return this;
2175 }
2176
2177 /**
2178 * Tells whether or not this string matches the given <a
2179 * href="../util/regex/Pattern.html#sum">regular expression</a>.
2180 *
2181 * <p> An invocation of this method of the form
2182 * <i>str</i>{@code .matches(}<i>regex</i>{@code )} yields exactly the
2183 * same result as the expression
2184 *
2185 * <blockquote>
2186 * {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#matches(String,CharSequence)
2187 * matches(<i>regex</i>, <i>str</i>)}
2188 * </blockquote>
2189 *
2190 * @param regex
2191 * the regular expression to which this string is to be matched
2192 *
2193 * @return {@code true} if, and only if, this string matches the
2194 * given regular expression
2195 *
2196 * @throws PatternSyntaxException
2197 * if the regular expression's syntax is invalid
2198 *
2199 * @see java.util.regex.Pattern
2200 *
2201 * @since 1.4
2202 * @spec JSR-51
2203 */
2204 public boolean matches(String regex) {
2205 return Pattern.matches(regex, this);
2206 }
2207
2208 /**
2209 * Returns true if and only if this string contains the specified
2210 * sequence of char values.
2211 *
2212 * @param s the sequence to search for
2213 * @return true if this string contains {@code s}, false otherwise
2214 * @since 1.5
2215 */
2216 public boolean contains(CharSequence s) {
2217 return indexOf(s.toString()) >= 0;
2218 }
2219
2220 /**
2221 * Replaces the first substring of this string that matches the given <a
2222 * href="../util/regex/Pattern.html#sum">regular expression</a> with the
2223 * given replacement.
2224 *
2225 * <p> An invocation of this method of the form
2226 * <i>str</i>{@code .replaceFirst(}<i>regex</i>{@code ,} <i>repl</i>{@code )}
2227 * yields exactly the same result as the expression
2228 *
2229 * <blockquote>
2230 * <code>
2231 * {@link java.util.regex.Pattern}.{@link
2232 * java.util.regex.Pattern#compile compile}(<i>regex</i>).{@link
2233 * java.util.regex.Pattern#matcher(java.lang.CharSequence) matcher}(<i>str</i>).{@link
2234 * java.util.regex.Matcher#replaceFirst replaceFirst}(<i>repl</i>)
2235 * </code>
2236 * </blockquote>
2237 *
2238 *<p>
2239 * Note that backslashes ({@code \}) and dollar signs ({@code $}) in the
2240 * replacement string may cause the results to be different than if it were
2241 * being treated as a literal replacement string; see
2242 * {@link java.util.regex.Matcher#replaceFirst}.
2243 * Use {@link java.util.regex.Matcher#quoteReplacement} to suppress the special
2244 * meaning of these characters, if desired.
2245 *
2246 * @param regex
2247 * the regular expression to which this string is to be matched
2248 * @param replacement
2249 * the string to be substituted for the first match
2250 *
2251 * @return The resulting {@code String}
2252 *
2253 * @throws PatternSyntaxException
2254 * if the regular expression's syntax is invalid
2255 *
2256 * @see java.util.regex.Pattern
2257 *
2258 * @since 1.4
2259 * @spec JSR-51
2260 */
2261 public String replaceFirst(String regex, String replacement) {
2262 return Pattern.compile(regex).matcher(this).replaceFirst(replacement);
2263 }
2264
2265 /**
2266 * Replaces each substring of this string that matches the given <a
2267 * href="../util/regex/Pattern.html#sum">regular expression</a> with the
2268 * given replacement.
2269 *
2270 * <p> An invocation of this method of the form
2271 * <i>str</i>{@code .replaceAll(}<i>regex</i>{@code ,} <i>repl</i>{@code )}
2272 * yields exactly the same result as the expression
2273 *
2274 * <blockquote>
2275 * <code>
2276 * {@link java.util.regex.Pattern}.{@link
2277 * java.util.regex.Pattern#compile compile}(<i>regex</i>).{@link
2278 * java.util.regex.Pattern#matcher(java.lang.CharSequence) matcher}(<i>str</i>).{@link
2279 * java.util.regex.Matcher#replaceAll replaceAll}(<i>repl</i>)
2280 * </code>
2281 * </blockquote>
2282 *
2283 *<p>
2284 * Note that backslashes ({@code \}) and dollar signs ({@code $}) in the
2285 * replacement string may cause the results to be different than if it were
2286 * being treated as a literal replacement string; see
2287 * {@link java.util.regex.Matcher#replaceAll Matcher.replaceAll}.
2288 * Use {@link java.util.regex.Matcher#quoteReplacement} to suppress the special
2289 * meaning of these characters, if desired.
2290 *
2291 * @param regex
2292 * the regular expression to which this string is to be matched
2293 * @param replacement
2294 * the string to be substituted for each match
2295 *
2296 * @return The resulting {@code String}
2297 *
2298 * @throws PatternSyntaxException
2299 * if the regular expression's syntax is invalid
2300 *
2301 * @see java.util.regex.Pattern
2302 *
2303 * @since 1.4
2304 * @spec JSR-51
2305 */
2306 public String replaceAll(String regex, String replacement) {
2307 return Pattern.compile(regex).matcher(this).replaceAll(replacement);
2308 }
2309
2310 /**
2311 * Replaces each substring of this string that matches the literal target
2312 * sequence with the specified literal replacement sequence. The
2313 * replacement proceeds from the beginning of the string to the end, for
2314 * example, replacing "aa" with "b" in the string "aaa" will result in
2315 * "ba" rather than "ab".
2316 *
2317 * @param target The sequence of char values to be replaced
2318 * @param replacement The replacement sequence of char values
2319 * @return The resulting string
2320 * @since 1.5
2321 */
2322 public String replace(CharSequence target, CharSequence replacement) {
2323 return Pattern.compile(target.toString(), Pattern.LITERAL).matcher(
2324 this).replaceAll(Matcher.quoteReplacement(replacement.toString()));
2325 }
2326
2327 /**
2328 * Splits this string around matches of the given
2329 * <a href="../util/regex/Pattern.html#sum">regular expression</a>.
2330 *
2331 * <p> The array returned by this method contains each substring of this
2332 * string that is terminated by another substring that matches the given
2333 * expression or is terminated by the end of the string. The substrings in
2334 * the array are in the order in which they occur in this string. If the
2335 * expression does not match any part of the input then the resulting array
2336 * has just one element, namely this string.
2337 *
2338 * <p> When there is a positive-width match at the beginning of this
2339 * string then an empty leading substring is included at the beginning
2340 * of the resulting array. A zero-width match at the beginning however
2341 * never produces such empty leading substring.
2342 *
2343 * <p> The {@code limit} parameter controls the number of times the
2344 * pattern is applied and therefore affects the length of the resulting
2345 * array. If the limit <i>n</i> is greater than zero then the pattern
2346 * will be applied at most <i>n</i> - 1 times, the array's
2347 * length will be no greater than <i>n</i>, and the array's last entry
2348 * will contain all input beyond the last matched delimiter. If <i>n</i>
2349 * is non-positive then the pattern will be applied as many times as
2350 * possible and the array can have any length. If <i>n</i> is zero then
2351 * the pattern will be applied as many times as possible, the array can
2352 * have any length, and trailing empty strings will be discarded.
2353 *
2354 * <p> The string {@code "boo:and:foo"}, for example, yields the
2355 * following results with these parameters:
2356 *
2357 * <blockquote><table cellpadding=1 cellspacing=0 summary="Split example showing regex, limit, and result">
2358 * <tr>
2359 * <th>Regex</th>
2360 * <th>Limit</th>
2361 * <th>Result</th>
2362 * </tr>
2363 * <tr><td align=center>:</td>
2364 * <td align=center>2</td>
2365 * <td>{@code { "boo", "and:foo" }}</td></tr>
2366 * <tr><td align=center>:</td>
2367 * <td align=center>5</td>
2368 * <td>{@code { "boo", "and", "foo" }}</td></tr>
2369 * <tr><td align=center>:</td>
2370 * <td align=center>-2</td>
2371 * <td>{@code { "boo", "and", "foo" }}</td></tr>
2372 * <tr><td align=center>o</td>
2373 * <td align=center>5</td>
2374 * <td>{@code { "b", "", ":and:f", "", "" }}</td></tr>
2375 * <tr><td align=center>o</td>
2376 * <td align=center>-2</td>
2377 * <td>{@code { "b", "", ":and:f", "", "" }}</td></tr>
2378 * <tr><td align=center>o</td>
2379 * <td align=center>0</td>
2380 * <td>{@code { "b", "", ":and:f" }}</td></tr>
2381 * </table></blockquote>
2382 *
2383 * <p> An invocation of this method of the form
2384 * <i>str.</i>{@code split(}<i>regex</i>{@code ,} <i>n</i>{@code )}
2385 * yields the same result as the expression
2386 *
2387 * <blockquote>
2388 * <code>
2389 * {@link java.util.regex.Pattern}.{@link
2390 * java.util.regex.Pattern#compile compile}(<i>regex</i>).{@link
2391 * java.util.regex.Pattern#split(java.lang.CharSequence,int) split}(<i>str</i>, <i>n</i>)
2392 * </code>
2393 * </blockquote>
2394 *
2395 *
2396 * @param regex
2397 * the delimiting regular expression
2398 *
2399 * @param limit
2400 * the result threshold, as described above
2401 *
2402 * @return the array of strings computed by splitting this string
2403 * around matches of the given regular expression
2404 *
2405 * @throws PatternSyntaxException
2406 * if the regular expression's syntax is invalid
2407 *
2408 * @see java.util.regex.Pattern
2409 *
2410 * @since 1.4
2411 * @spec JSR-51
2412 */
2413 public String[] split(String regex, int limit) {
2414 /* fastpath if the regex is a
2415 (1)one-char String and this character is not one of the
2416 RegEx's meta characters ".$|()[{^?*+\\", or
2417 (2)two-char String and the first char is the backslash and
2418 the second is not the ascii digit or ascii letter.
2419 */
2420 char ch = 0;
2421 if (((regex.value.length == 1 &&
2422 ".$|()[{^?*+\\".indexOf(ch = regex.charAt(0)) == -1) ||
2423 (regex.length() == 2 &&
2424 regex.charAt(0) == '\\' &&
2425 (((ch = regex.charAt(1))-'0')|('9'-ch)) < 0 &&
2426 ((ch-'a')|('z'-ch)) < 0 &&
2427 ((ch-'A')|('Z'-ch)) < 0)) &&
2428 (ch < Character.MIN_HIGH_SURROGATE ||
2429 ch > Character.MAX_LOW_SURROGATE))
2430 {
2431 int off = 0;
2432 int next = 0;
2433 boolean limited = limit > 0;
2434 ArrayList<String> list = new ArrayList<>();
2435 while ((next = indexOf(ch, off)) != -1) {
2436 if (!limited || list.size() < limit - 1) {
2437 list.add(substring(off, next));
2438 off = next + 1;
2439 } else { // last one
2440 //assert (list.size() == limit - 1);
2441 list.add(substring(off, value.length));
2442 off = value.length;
2443 break;
2444 }
2445 }
2446 // If no match was found, return this
2447 if (off == 0)
2448 return new String[]{this};
2449
2450 // Add remaining segment
2451 if (!limited || list.size() < limit)
2452 list.add(substring(off, value.length));
2453
2454 // Construct result
2455 int resultSize = list.size();
2456 if (limit == 0) {
2457 while (resultSize > 0 && list.get(resultSize - 1).length() == 0) {
2458 resultSize--;
2459 }
2460 }
2461 String[] result = new String[resultSize];
2462 return list.subList(0, resultSize).toArray(result);
2463 }
2464 return Pattern.compile(regex).split(this, limit);
2465 }
2466
2467 /**
2468 * Splits this string around matches of the given <a
2469 * href="../util/regex/Pattern.html#sum">regular expression</a>.
2470 *
2471 * <p> This method works as if by invoking the two-argument {@link
2472 * #split(String, int) split} method with the given expression and a limit
2473 * argument of zero. Trailing empty strings are therefore not included in
2474 * the resulting array.
2475 *
2476 * <p> The string {@code "boo:and:foo"}, for example, yields the following
2477 * results with these expressions:
2478 *
2479 * <blockquote><table cellpadding=1 cellspacing=0 summary="Split examples showing regex and result">
2480 * <tr>
2481 * <th>Regex</th>
2482 * <th>Result</th>
2483 * </tr>
2484 * <tr><td align=center>:</td>
2485 * <td>{@code { "boo", "and", "foo" }}</td></tr>
2486 * <tr><td align=center>o</td>
2487 * <td>{@code { "b", "", ":and:f" }}</td></tr>
2488 * </table></blockquote>
2489 *
2490 *
2491 * @param regex
2492 * the delimiting regular expression
2493 *
2494 * @return the array of strings computed by splitting this string
2495 * around matches of the given regular expression
2496 *
2497 * @throws PatternSyntaxException
2498 * if the regular expression's syntax is invalid
2499 *
2500 * @see java.util.regex.Pattern
2501 *
2502 * @since 1.4
2503 * @spec JSR-51
2504 */
2505 public String[] split(String regex) {
2506 return split(regex, 0);
2507 }
2508
2509 /**
2510 * Returns a new String composed of copies of the
2511 * {@code CharSequence elements} joined together with a copy of
2512 * the specified {@code delimiter}.
2513 *
2514 * <blockquote>For example,
2515 * <pre>{@code
2516 * String message = String.join("-", "Java", "is", "cool");
2517 * // message returned is: "Java-is-cool"
2518 * }</pre></blockquote>
2519 *
2520 * Note that if an element is null, then {@code "null"} is added.
2521 *
2522 * @param delimiter the delimiter that separates each element
2523 * @param elements the elements to join together.
2524 *
2525 * @return a new {@code String} that is composed of the {@code elements}
2526 * separated by the {@code delimiter}
2527 *
2528 * @throws NullPointerException If {@code delimiter} or {@code elements}
2529 * is {@code null}
2530 *
2531 * @see java.util.StringJoiner
2532 * @since 1.8
2533 */
2534 public static String join(CharSequence delimiter, CharSequence... elements) {
2535 Objects.requireNonNull(delimiter);
2536 Objects.requireNonNull(elements);
2537 // Number of elements not likely worth Arrays.stream overhead.
2538 StringJoiner joiner = new StringJoiner(delimiter);
2539 for (CharSequence cs: elements) {
2540 joiner.add(cs);
2541 }
2542 return joiner.toString();
2543 }
2544
2545 /**
2546 * Returns a new {@code String} composed of copies of the
2547 * {@code CharSequence elements} joined together with a copy of the
2548 * specified {@code delimiter}.
2549 *
2550 * <blockquote>For example,
2551 * <pre>{@code
2552 * List<String> strings = new LinkedList<>();
2553 * strings.add("Java");strings.add("is");
2554 * strings.add("cool");
2555 * String message = String.join(" ", strings);
2556 * //message returned is: "Java is cool"
2557 *
2558 * Set<String> strings = new LinkedHashSet<>();
2559 * strings.add("Java"); strings.add("is");
2560 * strings.add("very"); strings.add("cool");
2561 * String message = String.join("-", strings);
2562 * //message returned is: "Java-is-very-cool"
2563 * }</pre></blockquote>
2564 *
2565 * Note that if an individual element is {@code null}, then {@code "null"} is added.
2566 *
2567 * @param delimiter a sequence of characters that is used to separate each
2568 * of the {@code elements} in the resulting {@code String}
2569 * @param elements an {@code Iterable} that will have its {@code elements}
2570 * joined together.
2571 *
2572 * @return a new {@code String} that is composed from the {@code elements}
2573 * argument
2574 *
2575 * @throws NullPointerException If {@code delimiter} or {@code elements}
2576 * is {@code null}
2577 *
2578 * @see #join(CharSequence,CharSequence...)
2579 * @see java.util.StringJoiner
2580 * @since 1.8
2581 */
2582 public static String join(CharSequence delimiter,
2583 Iterable<? extends CharSequence> elements) {
2584 Objects.requireNonNull(delimiter);
2585 Objects.requireNonNull(elements);
2586 StringJoiner joiner = new StringJoiner(delimiter);
2587 for (CharSequence cs: elements) {
2588 joiner.add(cs);
2589 }
2590 return joiner.toString();
2591 }
2592
2593 /**
2594 * Converts all of the characters in this {@code String} to lower
2595 * case using the rules of the given {@code Locale}. Case mapping is based
2596 * on the Unicode Standard version specified by the {@link java.lang.Character Character}
2597 * class. Since case mappings are not always 1:1 char mappings, the resulting
2598 * {@code String} may be a different length than the original {@code String}.
2599 * <p>
2600 * Examples of lowercase mappings are in the following table:
2601 * <table border="1" summary="Lowercase mapping examples showing language code of locale, upper case, lower case, and description">
2602 * <tr>
2603 * <th>Language Code of Locale</th>
2604 * <th>Upper Case</th>
2605 * <th>Lower Case</th>
2606 * <th>Description</th>
2607 * </tr>
2608 * <tr>
2609 * <td>tr (Turkish)</td>
2610 * <td>\u0130</td>
2611 * <td>\u0069</td>
2612 * <td>capital letter I with dot above -> small letter i</td>
2613 * </tr>
2614 * <tr>
2615 * <td>tr (Turkish)</td>
2616 * <td>\u0049</td>
2617 * <td>\u0131</td>
2618 * <td>capital letter I -> small letter dotless i </td>
2619 * </tr>
2620 * <tr>
2621 * <td>(all)</td>
2622 * <td>French Fries</td>
2623 * <td>french fries</td>
2624 * <td>lowercased all chars in String</td>
2625 * </tr>
2626 * <tr>
2627 * <td>(all)</td>
2628 * <td><img src="doc-files/capiota.gif" alt="capiota"><img src="doc-files/capchi.gif" alt="capchi">
2629 * <img src="doc-files/captheta.gif" alt="captheta"><img src="doc-files/capupsil.gif" alt="capupsil">
2630 * <img src="doc-files/capsigma.gif" alt="capsigma"></td>
2631 * <td><img src="doc-files/iota.gif" alt="iota"><img src="doc-files/chi.gif" alt="chi">
2632 * <img src="doc-files/theta.gif" alt="theta"><img src="doc-files/upsilon.gif" alt="upsilon">
2633 * <img src="doc-files/sigma1.gif" alt="sigma"></td>
2634 * <td>lowercased all chars in String</td>
2635 * </tr>
2636 * </table>
2637 *
2638 * @param locale use the case transformation rules for this locale
2639 * @return the {@code String}, converted to lowercase.
2640 * @see java.lang.String#toLowerCase()
2641 * @see java.lang.String#toUpperCase()
2642 * @see java.lang.String#toUpperCase(Locale)
2643 * @since 1.1
2644 */
2645 public String toLowerCase(Locale locale) {
2646 if (locale == null) {
2647 throw new NullPointerException();
2648 }
2649 int first;
2650 boolean hasSurr = false;
2651 final int len = value.length;
2652
2653 // Now check if there are any characters that need to be changed, or are surrogate
2654 for (first = 0 ; first < len; first++) {
2655 int cp = (int)value[first];
2656 if (Character.isSurrogate((char)cp)) {
2657 hasSurr = true;
2658 break;
2659 }
2660 if (cp != Character.toLowerCase(cp)) { // no need to check Character.ERROR
2661 break;
2662 }
2663 }
2664 if (first == len)
2665 return this;
2666 char[] result = new char[len];
2667 System.arraycopy(value, 0, result, 0, first); // Just copy the first few
2668 // lowerCase characters.
2669 String lang = locale.getLanguage();
2670 if (lang == "tr" || lang == "az" || lang == "lt") {
2671 return toLowerCaseEx(result, first, locale, true);
2672 }
2673 if (hasSurr) {
2674 return toLowerCaseEx(result, first, locale, false);
2675 }
2676 for (int i = first; i < len; i++) {
2677 int cp = (int)value[i];
2678 if (cp == '\u03A3' || // GREEK CAPITAL LETTER SIGMA
2679 Character.isSurrogate((char)cp)) {
2680 return toLowerCaseEx(result, i, locale, false);
2681 }
2682 if (cp == '\u0130') { // LATIN CAPITAL LETTER I WITH DOT ABOVE
2683 return toLowerCaseEx(result, i, locale, true);
2684 }
2685 cp = Character.toLowerCase(cp);
2686 if (!Character.isBmpCodePoint(cp)) {
2687 return toLowerCaseEx(result, i, locale, false);
2688 }
2689 result[i] = (char)cp;
2690 }
2691 return new String(result, true);
2692 }
2693
2694 private String toLowerCaseEx(char[] result, int first, Locale locale, boolean localeDependent) {
2695 int resultOffset = first;
2696 int srcCount;
2697 for (int i = first; i < value.length; i += srcCount) {
2698 int srcChar = (int)value[i];
2699 int lowerChar;
2700 char[] lowerCharArray;
2701 srcCount = 1;
2702 if (Character.isSurrogate((char)srcChar)) {
2703 srcChar = codePointAt(i);
2704 srcCount = Character.charCount(srcChar);
2705 }
2706 if (localeDependent || srcChar == '\u03A3') { // GREEK CAPITAL LETTER SIGMA
2707 lowerChar = ConditionalSpecialCasing.toLowerCaseEx(this, i, locale);
2708 } else {
2709 lowerChar = Character.toLowerCase(srcChar);
2710 }
2711 if (Character.isBmpCodePoint(lowerChar)) { // Character.ERROR is not a bmp
2712 result[resultOffset++] = (char)lowerChar;
2713 } else {
2714 if (lowerChar == Character.ERROR) {
2715 lowerCharArray = ConditionalSpecialCasing.toLowerCaseCharArray(this, i, locale);
2716 } else if (srcCount == 2) {
2717 resultOffset += Character.toChars(lowerChar, result, resultOffset);
2718 continue;
2719 } else {
2720 lowerCharArray = Character.toChars(lowerChar);
2721 }
2722 /* Grow result if needed */
2723 int mapLen = lowerCharArray.length;
2724 if (mapLen > srcCount) {
2725 char[] result2 = new char[result.length + mapLen - srcCount];
2726 System.arraycopy(result, 0, result2, 0, resultOffset);
2727 result = result2;
2728 }
2729 for (int x = 0; x < mapLen; ++x) {
2730 result[resultOffset++] = lowerCharArray[x];
2731 }
2732 }
2733 }
2734 return new String(result, 0, resultOffset);
2735 }
2736
2737 /**
2738 * Converts all of the characters in this {@code String} to lower
2739 * case using the rules of the default locale. This is equivalent to calling
2740 * {@code toLowerCase(Locale.getDefault())}.
2741 * <p>
2742 * <b>Note:</b> This method is locale sensitive, and may produce unexpected
2743 * results if used for strings that are intended to be interpreted locale
2744 * independently.
2745 * Examples are programming language identifiers, protocol keys, and HTML
2746 * tags.
2747 * For instance, {@code "TITLE".toLowerCase()} in a Turkish locale
2748 * returns {@code "t\u005Cu0131tle"}, where '\u005Cu0131' is the
2749 * LATIN SMALL LETTER DOTLESS I character.
2750 * To obtain correct results for locale insensitive strings, use
2751 * {@code toLowerCase(Locale.ROOT)}.
2752 *
2753 * @return the {@code String}, converted to lowercase.
2754 * @see java.lang.String#toLowerCase(Locale)
2755 */
2756 public String toLowerCase() {
2757 return toLowerCase(Locale.getDefault());
2758 }
2759
2760 /**
2761 * Converts all of the characters in this {@code String} to upper
2762 * case using the rules of the given {@code Locale}. Case mapping is based
2763 * on the Unicode Standard version specified by the {@link java.lang.Character Character}
2764 * class. Since case mappings are not always 1:1 char mappings, the resulting
2765 * {@code String} may be a different length than the original {@code String}.
2766 * <p>
2767 * Examples of locale-sensitive and 1:M case mappings are in the following table.
2768 *
2769 * <table border="1" summary="Examples of locale-sensitive and 1:M case mappings. Shows Language code of locale, lower case, upper case, and description.">
2770 * <tr>
2771 * <th>Language Code of Locale</th>
2772 * <th>Lower Case</th>
2773 * <th>Upper Case</th>
2774 * <th>Description</th>
2775 * </tr>
2776 * <tr>
2777 * <td>tr (Turkish)</td>
2778 * <td>\u0069</td>
2779 * <td>\u0130</td>
2780 * <td>small letter i -> capital letter I with dot above</td>
2781 * </tr>
2782 * <tr>
2783 * <td>tr (Turkish)</td>
2784 * <td>\u0131</td>
2785 * <td>\u0049</td>
2786 * <td>small letter dotless i -> capital letter I</td>
2787 * </tr>
2788 * <tr>
2789 * <td>(all)</td>
2790 * <td>\u00df</td>
2791 * <td>\u0053 \u0053</td>
2792 * <td>small letter sharp s -> two letters: SS</td>
2793 * </tr>
2794 * <tr>
2795 * <td>(all)</td>
2796 * <td>Fahrvergnügen</td>
2797 * <td>FAHRVERGNÜGEN</td>
2798 * <td></td>
2799 * </tr>
2800 * </table>
2801 * @param locale use the case transformation rules for this locale
2802 * @return the {@code String}, converted to uppercase.
2803 * @see java.lang.String#toUpperCase()
2804 * @see java.lang.String#toLowerCase()
2805 * @see java.lang.String#toLowerCase(Locale)
2806 * @since 1.1
2807 */
2808 public String toUpperCase(Locale locale) {
2809 if (locale == null) {
2810 throw new NullPointerException();
2811 }
2812 int first;
2813 boolean hasSurr = false;
2814 final int len = value.length;
2815
2816 // Now check if there are any characters that need to be changed, or are surrogate
2817 for (first = 0 ; first < len; first++ ) {
2818 int cp = (int)value[first];
2819 if (Character.isSurrogate((char)cp)) {
2820 hasSurr = true;
2821 break;
2822 }
2823 if (cp != Character.toUpperCaseEx(cp)) { // no need to check Character.ERROR
2824 break;
2825 }
2826 }
2827 if (first == len) {
2828 return this;
2829 }
2830 char[] result = new char[len];
2831 System.arraycopy(value, 0, result, 0, first); // Just copy the first few
2832 // upperCase characters.
2833 String lang = locale.getLanguage();
2834 if (lang == "tr" || lang == "az" || lang == "lt") {
2835 return toUpperCaseEx(result, first, locale, true);
2836 }
2837 if (hasSurr) {
2838 return toUpperCaseEx(result, first, locale, false);
2839 }
2840 for (int i = first; i < len; i++) {
2841 int cp = (int)value[i];
2842 if (Character.isSurrogate((char)cp)) {
2843 return toUpperCaseEx(result, i, locale, false);
2844 }
2845 cp = Character.toUpperCaseEx(cp);
2846 if (!Character.isBmpCodePoint(cp)) { // Character.ERROR is not bmp
2847 return toUpperCaseEx(result, i, locale, false);
2848 }
2849 result[i] = (char)cp;
2850 }
2851 return new String(result, true);
2852 }
2853
2854 private String toUpperCaseEx(char[] result, int first, Locale locale,
2855 boolean localeDependent) {
2856 int resultOffset = first;
2857 int srcCount;
2858 for (int i = first; i < value.length; i += srcCount) {
2859 int srcChar = (int)value[i];
2860 int upperChar;
2861 char[] upperCharArray;
2862 srcCount = 1;
2863 if (Character.isSurrogate((char)srcChar)) {
2864 srcChar = codePointAt(i);
2865 srcCount = Character.charCount(srcChar);
2866 }
2867 if (localeDependent) {
2868 upperChar = ConditionalSpecialCasing.toUpperCaseEx(this, i, locale);
2869 } else {
2870 upperChar = Character.toUpperCaseEx(srcChar);
2871 }
2872 if (Character.isBmpCodePoint(upperChar)) {
2873 result[resultOffset++] = (char)upperChar;
2874 } else {
2875 if (upperChar == Character.ERROR) {
2876 if (localeDependent) {
2877 upperCharArray =
2878 ConditionalSpecialCasing.toUpperCaseCharArray(this, i, locale);
2879 } else {
2880 upperCharArray = Character.toUpperCaseCharArray(srcChar);
2881 }
2882 } else if (srcCount == 2) {
2883 resultOffset += Character.toChars(upperChar, result, resultOffset);
2884 continue;
2885 } else {
2886 upperCharArray = Character.toChars(upperChar);
2887 }
2888 /* Grow result if needed */
2889 int mapLen = upperCharArray.length;
2890 if (mapLen > srcCount) {
2891 char[] result2 = new char[result.length + mapLen - srcCount];
2892 System.arraycopy(result, 0, result2, 0, resultOffset);
2893 result = result2;
2894 }
2895 for (int x = 0; x < mapLen; ++x) {
2896 result[resultOffset++] = upperCharArray[x];
2897 }
2898 }
2899 }
2900 return new String(result, 0, resultOffset);
2901 }
2902
2903 /**
2904 * Converts all of the characters in this {@code String} to upper
2905 * case using the rules of the default locale. This method is equivalent to
2906 * {@code toUpperCase(Locale.getDefault())}.
2907 * <p>
2908 * <b>Note:</b> This method is locale sensitive, and may produce unexpected
2909 * results if used for strings that are intended to be interpreted locale
2910 * independently.
2911 * Examples are programming language identifiers, protocol keys, and HTML
2912 * tags.
2913 * For instance, {@code "title".toUpperCase()} in a Turkish locale
2914 * returns {@code "T\u005Cu0130TLE"}, where '\u005Cu0130' is the
2915 * LATIN CAPITAL LETTER I WITH DOT ABOVE character.
2916 * To obtain correct results for locale insensitive strings, use
2917 * {@code toUpperCase(Locale.ROOT)}.
2918 *
2919 * @return the {@code String}, converted to uppercase.
2920 * @see java.lang.String#toUpperCase(Locale)
2921 */
2922 public String toUpperCase() {
2923 return toUpperCase(Locale.getDefault());
2924 }
2925
2926 /**
2927 * Returns a string whose value is this string, with any leading and trailing
2928 * whitespace removed.
2929 * <p>
2930 * If this {@code String} object represents an empty character
2931 * sequence, or the first and last characters of character sequence
2932 * represented by this {@code String} object both have codes
2933 * greater than {@code '\u005Cu0020'} (the space character), then a
2934 * reference to this {@code String} object is returned.
2935 * <p>
2936 * Otherwise, if there is no character with a code greater than
2937 * {@code '\u005Cu0020'} in the string, then a
2938 * {@code String} object representing an empty string is
2939 * returned.
2940 * <p>
2941 * Otherwise, let <i>k</i> be the index of the first character in the
2942 * string whose code is greater than {@code '\u005Cu0020'}, and let
2943 * <i>m</i> be the index of the last character in the string whose code
2944 * is greater than {@code '\u005Cu0020'}. A {@code String}
2945 * object is returned, representing the substring of this string that
2946 * begins with the character at index <i>k</i> and ends with the
2947 * character at index <i>m</i>-that is, the result of
2948 * {@code this.substring(k, m + 1)}.
2949 * <p>
2950 * This method may be used to trim whitespace (as defined above) from
2951 * the beginning and end of a string.
2952 *
2953 * @return A string whose value is this string, with any leading and trailing white
2954 * space removed, or this string if it has no leading or
2955 * trailing white space.
2956 */
2957 public String trim() {
2958 int len = value.length;
2959 int st = 0;
2960 char[] val = value; /* avoid getfield opcode */
2961
2962 while ((st < len) && (val[st] <= ' ')) {
2963 st++;
2964 }
2965 while ((st < len) && (val[len - 1] <= ' ')) {
2966 len--;
2967 }
2968 return ((st > 0) || (len < value.length)) ? substring(st, len) : this;
2969 }
2970
2971 /**
2972 * This object (which is already a string!) is itself returned.
2973 *
2974 * @return the string itself.
2975 */
2976 public String toString() {
2977 return this;
2978 }
2979
2980 /**
2981 * Converts this string to a new character array.
2982 *
2983 * @return a newly allocated character array whose length is the length
2984 * of this string and whose contents are initialized to contain
2985 * the character sequence represented by this string.
2986 */
2987 public char[] toCharArray() {
2988 // Cannot use Arrays.copyOf because of class initialization order issues
2989 char result[] = new char[value.length];
2990 System.arraycopy(value, 0, result, 0, value.length);
2991 return result;
2992 }
2993
2994 /**
2995 * Returns a formatted string using the specified format string and
2996 * arguments.
2997 *
2998 * <p> The locale always used is the one returned by {@link
2999 * java.util.Locale#getDefault() Locale.getDefault()}.
3000 *
3001 * @param format
3002 * A <a href="../util/Formatter.html#syntax">format string</a>
3003 *
3004 * @param args
3005 * Arguments referenced by the format specifiers in the format
3006 * string. If there are more arguments than format specifiers, the
3007 * extra arguments are ignored. The number of arguments is
3008 * variable and may be zero. The maximum number of arguments is
3009 * limited by the maximum dimension of a Java array as defined by
3010 * <cite>The Java™ Virtual Machine Specification</cite>.
3011 * The behaviour on a
3012 * {@code null} argument depends on the <a
3013 * href="../util/Formatter.html#syntax">conversion</a>.
3014 *
3015 * @throws java.util.IllegalFormatException
3016 * If a format string contains an illegal syntax, a format
3017 * specifier that is incompatible with the given arguments,
3018 * insufficient arguments given the format string, or other
3019 * illegal conditions. For specification of all possible
3020 * formatting errors, see the <a
3021 * href="../util/Formatter.html#detail">Details</a> section of the
3022 * formatter class specification.
3023 *
3024 * @return A formatted string
3025 *
3026 * @see java.util.Formatter
3027 * @since 1.5
3028 */
3029 public static String format(String format, Object... args) {
3030 return new Formatter().format(format, args).toString();
3031 }
3032
3033 /**
3034 * Returns a formatted string using the specified locale, format string,
3035 * and arguments.
3036 *
3037 * @param l
3038 * The {@linkplain java.util.Locale locale} to apply during
3039 * formatting. If {@code l} is {@code null} then no localization
3040 * is applied.
3041 *
3042 * @param format
3043 * A <a href="../util/Formatter.html#syntax">format string</a>
3044 *
3045 * @param args
3046 * Arguments referenced by the format specifiers in the format
3047 * string. If there are more arguments than format specifiers, the
3048 * extra arguments are ignored. The number of arguments is
3049 * variable and may be zero. The maximum number of arguments is
3050 * limited by the maximum dimension of a Java array as defined by
3051 * <cite>The Java™ Virtual Machine Specification</cite>.
3052 * The behaviour on a
3053 * {@code null} argument depends on the
3054 * <a href="../util/Formatter.html#syntax">conversion</a>.
3055 *
3056 * @throws java.util.IllegalFormatException
3057 * If a format string contains an illegal syntax, a format
3058 * specifier that is incompatible with the given arguments,
3059 * insufficient arguments given the format string, or other
3060 * illegal conditions. For specification of all possible
3061 * formatting errors, see the <a
3062 * href="../util/Formatter.html#detail">Details</a> section of the
3063 * formatter class specification
3064 *
3065 * @return A formatted string
3066 *
3067 * @see java.util.Formatter
3068 * @since 1.5
3069 */
3070 public static String format(Locale l, String format, Object... args) {
3071 return new Formatter(l).format(format, args).toString();
3072 }
3073
3074 /**
3075 * Returns the string representation of the {@code Object} argument.
3076 *
3077 * @param obj an {@code Object}.
3078 * @return if the argument is {@code null}, then a string equal to
3079 * {@code "null"}; otherwise, the value of
3080 * {@code obj.toString()} is returned.
3081 * @see java.lang.Object#toString()
3082 */
3083 public static String valueOf(Object obj) {
3084 return (obj == null) ? "null" : obj.toString();
3085 }
3086
3087 /**
3088 * Returns the string representation of the {@code char} array
3089 * argument. The contents of the character array are copied; subsequent
3090 * modification of the character array does not affect the returned
3091 * string.
3092 *
3093 * @param data the character array.
3094 * @return a {@code String} that contains the characters of the
3095 * character array.
3096 */
3097 public static String valueOf(char data[]) {
3098 return new String(data);
3099 }
3100
3101 /**
3102 * Returns the string representation of a specific subarray of the
3103 * {@code char} array argument.
3104 * <p>
3105 * The {@code offset} argument is the index of the first
3106 * character of the subarray. The {@code count} argument
3107 * specifies the length of the subarray. The contents of the subarray
3108 * are copied; subsequent modification of the character array does not
3109 * affect the returned string.
3110 *
3111 * @param data the character array.
3112 * @param offset initial offset of the subarray.
3113 * @param count length of the subarray.
3114 * @return a {@code String} that contains the characters of the
3115 * specified subarray of the character array.
3116 * @exception IndexOutOfBoundsException if {@code offset} is
3117 * negative, or {@code count} is negative, or
3118 * {@code offset+count} is larger than
3119 * {@code data.length}.
3120 */
3121 public static String valueOf(char data[], int offset, int count) {
3122 return new String(data, offset, count);
3123 }
3124
3125 /**
3126 * Equivalent to {@link #valueOf(char[], int, int)}.
3127 *
3128 * @param data the character array.
3129 * @param offset initial offset of the subarray.
3130 * @param count length of the subarray.
3131 * @return a {@code String} that contains the characters of the
3132 * specified subarray of the character array.
3133 * @exception IndexOutOfBoundsException if {@code offset} is
3134 * negative, or {@code count} is negative, or
3135 * {@code offset+count} is larger than
3136 * {@code data.length}.
3137 */
3138 public static String copyValueOf(char data[], int offset, int count) {
3139 return new String(data, offset, count);
3140 }
3141
3142 /**
3143 * Equivalent to {@link #valueOf(char[])}.
3144 *
3145 * @param data the character array.
3146 * @return a {@code String} that contains the characters of the
3147 * character array.
3148 */
3149 public static String copyValueOf(char data[]) {
3150 return new String(data);
3151 }
3152
3153 /**
3154 * Returns the string representation of the {@code boolean} argument.
3155 *
3156 * @param b a {@code boolean}.
3157 * @return if the argument is {@code true}, a string equal to
3158 * {@code "true"} is returned; otherwise, a string equal to
3159 * {@code "false"} is returned.
3160 */
3161 public static String valueOf(boolean b) {
3162 return b ? "true" : "false";
3163 }
3164
3165 /**
3166 * Returns the string representation of the {@code char}
3167 * argument.
3168 *
3169 * @param c a {@code char}.
3170 * @return a string of length {@code 1} containing
3171 * as its single character the argument {@code c}.
3172 */
3173 public static String valueOf(char c) {
3174 char data[] = {c};
3175 return new String(data, true);
3176 }
3177
3178 /**
3179 * Returns the string representation of the {@code int} argument.
3180 * <p>
3181 * The representation is exactly the one returned by the
3182 * {@code Integer.toString} method of one argument.
3183 *
3184 * @param i an {@code int}.
3185 * @return a string representation of the {@code int} argument.
3186 * @see java.lang.Integer#toString(int, int)
3187 */
3188 public static String valueOf(int i) {
3189 return Integer.toString(i);
3190 }
3191
3192 /**
3193 * Returns the string representation of the {@code long} argument.
3194 * <p>
3195 * The representation is exactly the one returned by the
3196 * {@code Long.toString} method of one argument.
3197 *
3198 * @param l a {@code long}.
3199 * @return a string representation of the {@code long} argument.
3200 * @see java.lang.Long#toString(long)
3201 */
3202 public static String valueOf(long l) {
3203 return Long.toString(l);
3204 }
3205
3206 /**
3207 * Returns the string representation of the {@code float} argument.
3208 * <p>
3209 * The representation is exactly the one returned by the
3210 * {@code Float.toString} method of one argument.
3211 *
3212 * @param f a {@code float}.
3213 * @return a string representation of the {@code float} argument.
3214 * @see java.lang.Float#toString(float)
3215 */
3216 public static String valueOf(float f) {
3217 return Float.toString(f);
3218 }
3219
3220 /**
3221 * Returns the string representation of the {@code double} argument.
3222 * <p>
3223 * The representation is exactly the one returned by the
3224 * {@code Double.toString} method of one argument.
3225 *
3226 * @param d a {@code double}.
3227 * @return a string representation of the {@code double} argument.
3228 * @see java.lang.Double#toString(double)
3229 */
3230 public static String valueOf(double d) {
3231 return Double.toString(d);
3232 }
3233
3234 /**
3235 * Returns a canonical representation for the string object.
3236 * <p>
3237 * A pool of strings, initially empty, is maintained privately by the
3238 * class {@code String}.
3239 * <p>
3240 * When the intern method is invoked, if the pool already contains a
3241 * string equal to this {@code String} object as determined by
3242 * the {@link #equals(Object)} method, then the string from the pool is
3243 * returned. Otherwise, this {@code String} object is added to the
3244 * pool and a reference to this {@code String} object is returned.
3245 * <p>
3246 * It follows that for any two strings {@code s} and {@code t},
3247 * {@code s.intern() == t.intern()} is {@code true}
3248 * if and only if {@code s.equals(t)} is {@code true}.
3249 * <p>
3250 * All literal strings and string-valued constant expressions are
3251 * interned. String literals are defined in section 3.10.5 of the
3252 * <cite>The Java™ Language Specification</cite>.
3253 *
3254 * @return a string that has the same contents as this string, but is
3255 * guaranteed to be from a pool of unique strings.
3256 */
3257 public native String intern();
3258 }