1 /* 2 * Copyright (c) 2003, 2013, 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 sun.misc.FloatingDecimal; 29 import java.util.Arrays; 30 31 /** 32 * A mutable sequence of characters. 33 * <p> 34 * Implements a modifiable string. At any point in time it contains some 35 * particular sequence of characters, but the length and content of the 36 * sequence can be changed through certain method calls. 37 * 38 * <p>Unless otherwise noted, passing a {@code null} argument to a constructor 39 * or method in this class will cause a {@link NullPointerException} to be 40 * thrown. 41 * 42 * @author Michael McCloskey 43 * @author Martin Buchholz 44 * @author Ulf Zibis 45 * @since 1.5 46 */ 47 abstract class AbstractStringBuilder implements Appendable, CharSequence { 48 /** 49 * The value is used for character storage. 50 */ 51 char[] value; 52 53 /** 54 * The count is the number of characters used. 55 */ 56 int count; 57 58 /** 59 * This no-arg constructor is necessary for serialization of subclasses. 60 */ 61 AbstractStringBuilder() { 62 } 63 64 /** 65 * Creates an AbstractStringBuilder of the specified capacity. 66 */ 67 AbstractStringBuilder(int capacity) { 68 value = new char[capacity]; 69 } 70 71 /** 72 * Returns the length (character count). 73 * 74 * @return the length of the sequence of characters currently 75 * represented by this object 76 */ 77 @Override 78 public int length() { 79 return count; 80 } 81 82 /** 83 * Returns the current capacity. The capacity is the amount of storage 84 * available for newly inserted characters, beyond which an allocation 85 * will occur. 86 * 87 * @return the current capacity 88 */ 89 public int capacity() { 90 return value.length; 91 } 92 93 /** 94 * Ensures that the capacity is at least equal to the specified minimum. 95 * If the current capacity is less than the argument, then a new internal 96 * array is allocated with greater capacity. The new capacity is the 97 * larger of: 98 * <ul> 99 * <li>The {@code minimumCapacity} argument. 100 * <li>Twice the old capacity, plus {@code 2}. 101 * </ul> 102 * If the {@code minimumCapacity} argument is nonpositive, this 103 * method takes no action and simply returns. 104 * Note that subsequent operations on this object can reduce the 105 * actual capacity below that requested here. 106 * 107 * @param minimumCapacity the minimum desired capacity. 108 */ 109 public void ensureCapacity(int minimumCapacity) { 110 if (minimumCapacity > 0) 111 ensureCapacityInternal(minimumCapacity); 112 } 113 114 /** 115 * This method has the same contract as ensureCapacity, but is 116 * never synchronized. 117 */ 118 private void ensureCapacityInternal(int minimumCapacity) { 119 // overflow-conscious code 120 if (minimumCapacity - value.length > 0) 121 expandCapacity(minimumCapacity); 122 } 123 124 /** 125 * This implements the expansion semantics of ensureCapacity with no 126 * size check or synchronization. 127 */ 128 void expandCapacity(int minimumCapacity) { 129 int newCapacity = value.length * 2 + 2; 130 if (newCapacity - minimumCapacity < 0) 131 newCapacity = minimumCapacity; 132 if (newCapacity < 0) { 133 if (minimumCapacity < 0) // overflow 134 throw new OutOfMemoryError(); 135 newCapacity = Integer.MAX_VALUE; 136 } 137 value = Arrays.copyOf(value, newCapacity); 138 } 139 140 /** 141 * Attempts to reduce storage used for the character sequence. 142 * If the buffer is larger than necessary to hold its current sequence of 143 * characters, then it may be resized to become more space efficient. 144 * Calling this method may, but is not required to, affect the value 145 * returned by a subsequent call to the {@link #capacity()} method. 146 */ 147 public void trimToSize() { 148 if (count < value.length) { 149 value = Arrays.copyOf(value, count); 150 } 151 } 152 153 /** 154 * Sets the length of the character sequence. 155 * The sequence is changed to a new character sequence 156 * whose length is specified by the argument. For every nonnegative 157 * index <i>k</i> less than {@code newLength}, the character at 158 * index <i>k</i> in the new character sequence is the same as the 159 * character at index <i>k</i> in the old sequence if <i>k</i> is less 160 * than the length of the old character sequence; otherwise, it is the 161 * null character {@code '\u005Cu0000'}. 162 * 163 * In other words, if the {@code newLength} argument is less than 164 * the current length, the length is changed to the specified length. 165 * <p> 166 * If the {@code newLength} argument is greater than or equal 167 * to the current length, sufficient null characters 168 * ({@code '\u005Cu0000'}) are appended so that 169 * length becomes the {@code newLength} argument. 170 * <p> 171 * The {@code newLength} argument must be greater than or equal 172 * to {@code 0}. 173 * 174 * @param newLength the new length 175 * @throws IndexOutOfBoundsException if the 176 * {@code newLength} argument is negative. 177 */ 178 public void setLength(int newLength) { 179 if (newLength < 0) 180 throw new StringIndexOutOfBoundsException(newLength); 181 ensureCapacityInternal(newLength); 182 183 if (count < newLength) { 184 Arrays.fill(value, count, newLength, '\0'); 185 } 186 187 count = newLength; 188 } 189 190 /** 191 * Returns the {@code char} value in this sequence at the specified index. 192 * The first {@code char} value is at index {@code 0}, the next at index 193 * {@code 1}, and so on, as in array indexing. 194 * <p> 195 * The index argument must be greater than or equal to 196 * {@code 0}, and less than the length of this sequence. 197 * 198 * <p>If the {@code char} value specified by the index is a 199 * <a href="Character.html#unicode">surrogate</a>, the surrogate 200 * value is returned. 201 * 202 * @param index the index of the desired {@code char} value. 203 * @return the {@code char} value at the specified index. 204 * @throws IndexOutOfBoundsException if {@code index} is 205 * negative or greater than or equal to {@code length()}. 206 */ 207 @Override 208 public char charAt(int index) { 209 if ((index < 0) || (index >= count)) 210 throw new StringIndexOutOfBoundsException(index); 211 return value[index]; 212 } 213 214 /** 215 * Returns the character (Unicode code point) at the specified 216 * index. The index refers to {@code char} values 217 * (Unicode code units) and ranges from {@code 0} to 218 * {@link #length()}{@code - 1}. 219 * 220 * <p> If the {@code char} value specified at the given index 221 * is in the high-surrogate range, the following index is less 222 * than the length of this sequence, and the 223 * {@code char} value at the following index is in the 224 * low-surrogate range, then the supplementary code point 225 * corresponding to this surrogate pair is returned. Otherwise, 226 * the {@code char} value at the given index is returned. 227 * 228 * @param index the index to the {@code char} values 229 * @return the code point value of the character at the 230 * {@code index} 231 * @exception IndexOutOfBoundsException if the {@code index} 232 * argument is negative or not less than the length of this 233 * sequence. 234 */ 235 public int codePointAt(int index) { 236 if ((index < 0) || (index >= count)) { 237 throw new StringIndexOutOfBoundsException(index); 238 } 239 return Character.codePointAtImpl(value, index, count); 240 } 241 242 /** 243 * Returns the character (Unicode code point) before the specified 244 * index. The index refers to {@code char} values 245 * (Unicode code units) and ranges from {@code 1} to {@link 246 * #length()}. 247 * 248 * <p> If the {@code char} value at {@code (index - 1)} 249 * is in the low-surrogate range, {@code (index - 2)} is not 250 * negative, and the {@code char} value at {@code (index - 251 * 2)} is in the high-surrogate range, then the 252 * supplementary code point value of the surrogate pair is 253 * returned. If the {@code char} value at {@code index - 254 * 1} is an unpaired low-surrogate or a high-surrogate, the 255 * surrogate value is returned. 256 * 257 * @param index the index following the code point that should be returned 258 * @return the Unicode code point value before the given index. 259 * @exception IndexOutOfBoundsException if the {@code index} 260 * argument is less than 1 or greater than the length 261 * of this sequence. 262 */ 263 public int codePointBefore(int index) { 264 int i = index - 1; 265 if ((i < 0) || (i >= count)) { 266 throw new StringIndexOutOfBoundsException(index); 267 } 268 return Character.codePointBeforeImpl(value, index, 0); 269 } 270 271 /** 272 * Returns the number of Unicode code points in the specified text 273 * range of this sequence. The text range begins at the specified 274 * {@code beginIndex} and extends to the {@code char} at 275 * index {@code endIndex - 1}. Thus the length (in 276 * {@code char}s) of the text range is 277 * {@code endIndex-beginIndex}. Unpaired surrogates within 278 * this sequence count as one code point each. 279 * 280 * @param beginIndex the index to the first {@code char} of 281 * the text range. 282 * @param endIndex the index after the last {@code char} of 283 * the text range. 284 * @return the number of Unicode code points in the specified text 285 * range 286 * @exception IndexOutOfBoundsException if the 287 * {@code beginIndex} is negative, or {@code endIndex} 288 * is larger than the length of this sequence, or 289 * {@code beginIndex} is larger than {@code endIndex}. 290 */ 291 public int codePointCount(int beginIndex, int endIndex) { 292 if (beginIndex < 0 || endIndex > count || beginIndex > endIndex) { 293 throw new IndexOutOfBoundsException(); 294 } 295 return Character.codePointCountImpl(value, beginIndex, endIndex-beginIndex); 296 } 297 298 /** 299 * Returns the index within this sequence that is offset from the 300 * given {@code index} by {@code codePointOffset} code 301 * points. Unpaired surrogates within the text range given by 302 * {@code index} and {@code codePointOffset} count as 303 * one code point each. 304 * 305 * @param index the index to be offset 306 * @param codePointOffset the offset in code points 307 * @return the index within this sequence 308 * @exception IndexOutOfBoundsException if {@code index} 309 * is negative or larger then the length of this sequence, 310 * or if {@code codePointOffset} is positive and the subsequence 311 * starting with {@code index} has fewer than 312 * {@code codePointOffset} code points, 313 * or if {@code codePointOffset} is negative and the subsequence 314 * before {@code index} has fewer than the absolute value of 315 * {@code codePointOffset} code points. 316 */ 317 public int offsetByCodePoints(int index, int codePointOffset) { 318 if (index < 0 || index > count) { 319 throw new IndexOutOfBoundsException(); 320 } 321 return Character.offsetByCodePointsImpl(value, 0, count, 322 index, codePointOffset); 323 } 324 325 /** 326 * Characters are copied from this sequence into the 327 * destination character array {@code dst}. The first character to 328 * be copied is at index {@code srcBegin}; the last character to 329 * be copied is at index {@code srcEnd-1}. The total number of 330 * characters to be copied is {@code srcEnd-srcBegin}. The 331 * characters are copied into the subarray of {@code dst} starting 332 * at index {@code dstBegin} and ending at index: 333 * <p><blockquote><pre> 334 * dstbegin + (srcEnd-srcBegin) - 1 335 * </pre></blockquote> 336 * 337 * @param srcBegin start copying at this offset. 338 * @param srcEnd stop copying at this offset. 339 * @param dst the array to copy the data into. 340 * @param dstBegin offset into {@code dst}. 341 * @throws IndexOutOfBoundsException if any of the following is true: 342 * <ul> 343 * <li>{@code srcBegin} is negative 344 * <li>{@code dstBegin} is negative 345 * <li>the {@code srcBegin} argument is greater than 346 * the {@code srcEnd} argument. 347 * <li>{@code srcEnd} is greater than 348 * {@code this.length()}. 349 * <li>{@code dstBegin+srcEnd-srcBegin} is greater than 350 * {@code dst.length} 351 * </ul> 352 */ 353 public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) 354 { 355 if (srcBegin < 0) 356 throw new StringIndexOutOfBoundsException(srcBegin); 357 if ((srcEnd < 0) || (srcEnd > count)) 358 throw new StringIndexOutOfBoundsException(srcEnd); 359 if (srcBegin > srcEnd) 360 throw new StringIndexOutOfBoundsException("srcBegin > srcEnd"); 361 System.arraycopy(value, srcBegin, dst, dstBegin, srcEnd - srcBegin); 362 } 363 364 /** 365 * The character at the specified index is set to {@code ch}. This 366 * sequence is altered to represent a new character sequence that is 367 * identical to the old character sequence, except that it contains the 368 * character {@code ch} at position {@code index}. 369 * <p> 370 * The index argument must be greater than or equal to 371 * {@code 0}, and less than the length of this sequence. 372 * 373 * @param index the index of the character to modify. 374 * @param ch the new character. 375 * @throws IndexOutOfBoundsException if {@code index} is 376 * negative or greater than or equal to {@code length()}. 377 */ 378 public void setCharAt(int index, char ch) { 379 if ((index < 0) || (index >= count)) 380 throw new StringIndexOutOfBoundsException(index); 381 value[index] = ch; 382 } 383 384 /** 385 * Appends the string representation of the {@code Object} argument. 386 * <p> 387 * The overall effect is exactly as if the argument were converted 388 * to a string by the method {@link String#valueOf(Object)}, 389 * and the characters of that string were then 390 * {@link #append(String) appended} to this character sequence. 391 * 392 * @param obj an {@code Object}. 393 * @return a reference to this object. 394 */ 395 public AbstractStringBuilder append(Object obj) { 396 return append(String.valueOf(obj)); 397 } 398 399 /** 400 * Appends the specified string to this character sequence. 401 * <p> 402 * The characters of the {@code String} argument are appended, in 403 * order, increasing the length of this sequence by the length of the 404 * argument. If {@code str} is {@code null}, then the four 405 * characters {@code "null"} are appended. 406 * <p> 407 * Let <i>n</i> be the length of this character sequence just prior to 408 * execution of the {@code append} method. Then the character at 409 * index <i>k</i> in the new character sequence is equal to the character 410 * at index <i>k</i> in the old character sequence, if <i>k</i> is less 411 * than <i>n</i>; otherwise, it is equal to the character at index 412 * <i>k-n</i> in the argument {@code str}. 413 * 414 * @param str a string. 415 * @return a reference to this object. 416 */ 417 public AbstractStringBuilder append(String str) { 418 if (str == null) 419 return appendNull(); 420 int len = str.length(); 421 ensureCapacityInternal(count + len); 422 str.getChars(0, len, value, count); 423 count += len; 424 return this; 425 } 426 427 // Documentation in subclasses because of synchro difference 428 public AbstractStringBuilder append(StringBuffer sb) { 429 if (sb == null) 430 return appendNull(); 431 int len = sb.length(); 432 ensureCapacityInternal(count + len); 433 sb.getChars(0, len, value, count); 434 count += len; 435 return this; 436 } 437 438 /** 439 * @since 1.8 440 */ 441 AbstractStringBuilder append(AbstractStringBuilder asb) { 442 if (asb == null) 443 return appendNull(); 444 int len = asb.length(); 445 ensureCapacityInternal(count + len); 446 asb.getChars(0, len, value, count); 447 count += len; 448 return this; 449 } 450 451 // Documentation in subclasses because of synchro difference 452 @Override 453 public AbstractStringBuilder append(CharSequence s) { 454 if (s == null) 455 return appendNull(); 456 if (s instanceof String) 457 return this.append((String)s); 458 if (s instanceof AbstractStringBuilder) 459 return this.append((AbstractStringBuilder)s); 460 461 return this.append(s, 0, s.length()); 462 } 463 464 private AbstractStringBuilder appendNull() { 465 int c = count; 466 ensureCapacityInternal(c + 4); 467 final char[] value = this.value; 468 value[c++] = 'n'; 469 value[c++] = 'u'; 470 value[c++] = 'l'; 471 value[c++] = 'l'; 472 count = c; 473 return this; 474 } 475 476 /** 477 * Appends a subsequence of the specified {@code CharSequence} to this 478 * sequence. 479 * <p> 480 * Characters of the argument {@code s}, starting at 481 * index {@code start}, are appended, in order, to the contents of 482 * this sequence up to the (exclusive) index {@code end}. The length 483 * of this sequence is increased by the value of {@code end - start}. 484 * <p> 485 * Let <i>n</i> be the length of this character sequence just prior to 486 * execution of the {@code append} method. Then the character at 487 * index <i>k</i> in this character sequence becomes equal to the 488 * character at index <i>k</i> in this sequence, if <i>k</i> is less than 489 * <i>n</i>; otherwise, it is equal to the character at index 490 * <i>k+start-n</i> in the argument {@code s}. 491 * <p> 492 * If {@code s} is {@code null}, then this method appends 493 * characters as if the s parameter was a sequence containing the four 494 * characters {@code "null"}. 495 * 496 * @param s the sequence to append. 497 * @param start the starting index of the subsequence to be appended. 498 * @param end the end index of the subsequence to be appended. 499 * @return a reference to this object. 500 * @throws IndexOutOfBoundsException if 501 * {@code start} is negative, or 502 * {@code start} is greater than {@code end} or 503 * {@code end} is greater than {@code s.length()} 504 */ 505 @Override 506 public AbstractStringBuilder append(CharSequence s, int start, int end) { 507 if (s == null) 508 s = "null"; 509 if ((start < 0) || (start > end) || (end > s.length())) 510 throw new IndexOutOfBoundsException( 511 "start " + start + ", end " + end + ", s.length() " 512 + s.length()); 513 int len = end - start; 514 ensureCapacityInternal(count + len); 515 for (int i = start, j = count; i < end; i++, j++) 516 value[j] = s.charAt(i); 517 count += len; 518 return this; 519 } 520 521 /** 522 * Appends the string representation of the {@code char} array 523 * argument to this sequence. 524 * <p> 525 * The characters of the array argument are appended, in order, to 526 * the contents of this sequence. The length of this sequence 527 * increases by the length of the argument. 528 * <p> 529 * The overall effect is exactly as if the argument were converted 530 * to a string by the method {@link String#valueOf(char[])}, 531 * and the characters of that string were then 532 * {@link #append(String) appended} to this character sequence. 533 * 534 * @param str the characters to be appended. 535 * @return a reference to this object. 536 */ 537 public AbstractStringBuilder append(char[] str) { 538 int len = str.length; 539 ensureCapacityInternal(count + len); 540 System.arraycopy(str, 0, value, count, len); 541 count += len; 542 return this; 543 } 544 545 /** 546 * Appends the string representation of a subarray of the 547 * {@code char} array argument to this sequence. 548 * <p> 549 * Characters of the {@code char} array {@code str}, starting at 550 * index {@code offset}, are appended, in order, to the contents 551 * of this sequence. The length of this sequence increases 552 * by the value of {@code len}. 553 * <p> 554 * The overall effect is exactly as if the arguments were converted 555 * to a string by the method {@link String#valueOf(char[],int,int)}, 556 * and the characters of that string were then 557 * {@link #append(String) appended} to this character sequence. 558 * 559 * @param str the characters to be appended. 560 * @param offset the index of the first {@code char} to append. 561 * @param len the number of {@code char}s to append. 562 * @return a reference to this object. 563 * @throws IndexOutOfBoundsException 564 * if {@code offset < 0} or {@code len < 0} 565 * or {@code offset+len > str.length} 566 */ 567 public AbstractStringBuilder append(char str[], int offset, int len) { 568 if (len > 0) // let arraycopy report AIOOBE for len < 0 569 ensureCapacityInternal(count + len); 570 System.arraycopy(str, offset, value, count, len); 571 count += len; 572 return this; 573 } 574 575 /** 576 * Appends the string representation of the {@code boolean} 577 * argument to the sequence. 578 * <p> 579 * The overall effect is exactly as if the argument were converted 580 * to a string by the method {@link String#valueOf(boolean)}, 581 * and the characters of that string were then 582 * {@link #append(String) appended} to this character sequence. 583 * 584 * @param b a {@code boolean}. 585 * @return a reference to this object. 586 */ 587 public AbstractStringBuilder append(boolean b) { 588 if (b) { 589 ensureCapacityInternal(count + 4); 590 value[count++] = 't'; 591 value[count++] = 'r'; 592 value[count++] = 'u'; 593 value[count++] = 'e'; 594 } else { 595 ensureCapacityInternal(count + 5); 596 value[count++] = 'f'; 597 value[count++] = 'a'; 598 value[count++] = 'l'; 599 value[count++] = 's'; 600 value[count++] = 'e'; 601 } 602 return this; 603 } 604 605 /** 606 * Appends the string representation of the {@code char} 607 * argument to this sequence. 608 * <p> 609 * The argument is appended to the contents of this sequence. 610 * The length of this sequence increases by {@code 1}. 611 * <p> 612 * The overall effect is exactly as if the argument were converted 613 * to a string by the method {@link String#valueOf(char)}, 614 * and the character in that string were then 615 * {@link #append(String) appended} to this character sequence. 616 * 617 * @param c a {@code char}. 618 * @return a reference to this object. 619 */ 620 @Override 621 public AbstractStringBuilder append(char c) { 622 ensureCapacityInternal(count + 1); 623 value[count++] = c; 624 return this; 625 } 626 627 /** 628 * Appends the string representation of the {@code int} 629 * argument to this sequence. 630 * <p> 631 * The overall effect is exactly as if the argument were converted 632 * to a string by the method {@link String#valueOf(int)}, 633 * and the characters of that string were then 634 * {@link #append(String) appended} to this character sequence. 635 * 636 * @param i an {@code int}. 637 * @return a reference to this object. 638 */ 639 public AbstractStringBuilder append(int i) { 640 if (i == Integer.MIN_VALUE) { 641 append("-2147483648"); 642 return this; 643 } 644 int appendedLength = (i < 0) ? Integer.stringSize(-i) + 1 645 : Integer.stringSize(i); 646 int spaceNeeded = count + appendedLength; 647 ensureCapacityInternal(spaceNeeded); 648 Integer.getChars(i, spaceNeeded, value); 649 count = spaceNeeded; 650 return this; 651 } 652 653 /** 654 * Appends the string representation of the {@code long} 655 * argument to this sequence. 656 * <p> 657 * The overall effect is exactly as if the argument were converted 658 * to a string by the method {@link String#valueOf(long)}, 659 * and the characters of that string were then 660 * {@link #append(String) appended} to this character sequence. 661 * 662 * @param l a {@code long}. 663 * @return a reference to this object. 664 */ 665 public AbstractStringBuilder append(long l) { 666 if (l == Long.MIN_VALUE) { 667 append("-9223372036854775808"); 668 return this; 669 } 670 int appendedLength = (l < 0) ? Long.stringSize(-l) + 1 671 : Long.stringSize(l); 672 int spaceNeeded = count + appendedLength; 673 ensureCapacityInternal(spaceNeeded); 674 Long.getChars(l, spaceNeeded, value); 675 count = spaceNeeded; 676 return this; 677 } 678 679 /** 680 * Appends the string representation of the {@code float} 681 * argument to this sequence. 682 * <p> 683 * The overall effect is exactly as if the argument were converted 684 * to a string by the method {@link String#valueOf(float)}, 685 * and the characters of that string were then 686 * {@link #append(String) appended} to this character sequence. 687 * 688 * @param f a {@code float}. 689 * @return a reference to this object. 690 */ 691 public AbstractStringBuilder append(float f) { 692 FloatingDecimal.appendTo(f,this); 693 return this; 694 } 695 696 /** 697 * Appends the string representation of the {@code double} 698 * argument to this sequence. 699 * <p> 700 * The overall effect is exactly as if the argument were converted 701 * to a string by the method {@link String#valueOf(double)}, 702 * and the characters of that string were then 703 * {@link #append(String) appended} to this character sequence. 704 * 705 * @param d a {@code double}. 706 * @return a reference to this object. 707 */ 708 public AbstractStringBuilder append(double d) { 709 FloatingDecimal.appendTo(d,this); 710 return this; 711 } 712 713 /** 714 * Removes the characters in a substring of this sequence. 715 * The substring begins at the specified {@code start} and extends to 716 * the character at index {@code end - 1} or to the end of the 717 * sequence if no such character exists. If 718 * {@code start} is equal to {@code end}, no changes are made. 719 * 720 * @param start The beginning index, inclusive. 721 * @param end The ending index, exclusive. 722 * @return This object. 723 * @throws StringIndexOutOfBoundsException if {@code start} 724 * is negative, greater than {@code length()}, or 725 * greater than {@code end}. 726 */ 727 public AbstractStringBuilder delete(int start, int end) { 728 if (start < 0) 729 throw new StringIndexOutOfBoundsException(start); 730 if (end > count) 731 end = count; 732 if (start > end) 733 throw new StringIndexOutOfBoundsException(); 734 int len = end - start; 735 if (len > 0) { 736 System.arraycopy(value, start+len, value, start, count-end); 737 count -= len; 738 } 739 return this; 740 } 741 742 /** 743 * Appends the string representation of the {@code codePoint} 744 * argument to this sequence. 745 * 746 * <p> The argument is appended to the contents of this sequence. 747 * The length of this sequence increases by 748 * {@link Character#charCount(int) Character.charCount(codePoint)}. 749 * 750 * <p> The overall effect is exactly as if the argument were 751 * converted to a {@code char} array by the method 752 * {@link Character#toChars(int)} and the character in that array 753 * were then {@link #append(char[]) appended} to this character 754 * sequence. 755 * 756 * @param codePoint a Unicode code point 757 * @return a reference to this object. 758 * @exception IllegalArgumentException if the specified 759 * {@code codePoint} isn't a valid Unicode code point 760 */ 761 public AbstractStringBuilder appendCodePoint(int codePoint) { 762 final int count = this.count; 763 764 if (Character.isBmpCodePoint(codePoint)) { 765 ensureCapacityInternal(count + 1); 766 value[count] = (char) codePoint; 767 this.count = count + 1; 768 } else if (Character.isValidCodePoint(codePoint)) { 769 ensureCapacityInternal(count + 2); 770 Character.toSurrogates(codePoint, value, count); 771 this.count = count + 2; 772 } else { 773 throw new IllegalArgumentException(); 774 } 775 return this; 776 } 777 778 /** 779 * Removes the {@code char} at the specified position in this 780 * sequence. This sequence is shortened by one {@code char}. 781 * 782 * <p>Note: If the character at the given index is a supplementary 783 * character, this method does not remove the entire character. If 784 * correct handling of supplementary characters is required, 785 * determine the number of {@code char}s to remove by calling 786 * {@code Character.charCount(thisSequence.codePointAt(index))}, 787 * where {@code thisSequence} is this sequence. 788 * 789 * @param index Index of {@code char} to remove 790 * @return This object. 791 * @throws StringIndexOutOfBoundsException if the {@code index} 792 * is negative or greater than or equal to 793 * {@code length()}. 794 */ 795 public AbstractStringBuilder deleteCharAt(int index) { 796 if ((index < 0) || (index >= count)) 797 throw new StringIndexOutOfBoundsException(index); 798 System.arraycopy(value, index+1, value, index, count-index-1); 799 count--; 800 return this; 801 } 802 803 /** 804 * Replaces the characters in a substring of this sequence 805 * with characters in the specified {@code String}. The substring 806 * begins at the specified {@code start} and extends to the character 807 * at index {@code end - 1} or to the end of the 808 * sequence if no such character exists. First the 809 * characters in the substring are removed and then the specified 810 * {@code String} is inserted at {@code start}. (This 811 * sequence will be lengthened to accommodate the 812 * specified String if necessary.) 813 * 814 * @param start The beginning index, inclusive. 815 * @param end The ending index, exclusive. 816 * @param str String that will replace previous contents. 817 * @return This object. 818 * @throws StringIndexOutOfBoundsException if {@code start} 819 * is negative, greater than {@code length()}, or 820 * greater than {@code end}. 821 */ 822 public AbstractStringBuilder replace(int start, int end, String str) { 823 if (start < 0) 824 throw new StringIndexOutOfBoundsException(start); 825 if (start > count) 826 throw new StringIndexOutOfBoundsException("start > length()"); 827 if (start > end) 828 throw new StringIndexOutOfBoundsException("start > end"); 829 830 if (end > count) 831 end = count; 832 int len = str.length(); 833 int newCount = count + len - (end - start); 834 ensureCapacityInternal(newCount); 835 836 System.arraycopy(value, end, value, start + len, count - end); 837 str.getChars(value, start); 838 count = newCount; 839 return this; 840 } 841 842 /** 843 * Returns a new {@code String} that contains a subsequence of 844 * characters currently contained in this character sequence. The 845 * substring begins at the specified index and extends to the end of 846 * this sequence. 847 * 848 * @param start The beginning index, inclusive. 849 * @return The new string. 850 * @throws StringIndexOutOfBoundsException if {@code start} is 851 * less than zero, or greater than the length of this object. 852 */ 853 public String substring(int start) { 854 return substring(start, count); 855 } 856 857 /** 858 * Returns a new character sequence that is a subsequence of this sequence. 859 * 860 * <p> An invocation of this method of the form 861 * 862 * <blockquote><pre> 863 * sb.subSequence(begin, end)</pre></blockquote> 864 * 865 * behaves in exactly the same way as the invocation 866 * 867 * <blockquote><pre> 868 * sb.substring(begin, end)</pre></blockquote> 869 * 870 * This method is provided so that this class can 871 * implement the {@link CharSequence} interface. </p> 872 * 873 * @param start the start index, inclusive. 874 * @param end the end index, exclusive. 875 * @return the specified subsequence. 876 * 877 * @throws IndexOutOfBoundsException 878 * if {@code start} or {@code end} are negative, 879 * if {@code end} is greater than {@code length()}, 880 * or if {@code start} is greater than {@code end} 881 * @spec JSR-51 882 */ 883 @Override 884 public CharSequence subSequence(int start, int end) { 885 return substring(start, end); 886 } 887 888 /** 889 * Returns a new {@code String} that contains a subsequence of 890 * characters currently contained in this sequence. The 891 * substring begins at the specified {@code start} and 892 * extends to the character at index {@code end - 1}. 893 * 894 * @param start The beginning index, inclusive. 895 * @param end The ending index, exclusive. 896 * @return The new string. 897 * @throws StringIndexOutOfBoundsException if {@code start} 898 * or {@code end} are negative or greater than 899 * {@code length()}, or {@code start} is 900 * greater than {@code end}. 901 */ 902 public String substring(int start, int end) { 903 if (start < 0) 904 throw new StringIndexOutOfBoundsException(start); 905 if (end > count) 906 throw new StringIndexOutOfBoundsException(end); 907 if (start > end) 908 throw new StringIndexOutOfBoundsException(end - start); 909 return new String(value, start, end - start); 910 } 911 912 /** 913 * Inserts the string representation of a subarray of the {@code str} 914 * array argument into this sequence. The subarray begins at the 915 * specified {@code offset} and extends {@code len} {@code char}s. 916 * The characters of the subarray are inserted into this sequence at 917 * the position indicated by {@code index}. The length of this 918 * sequence increases by {@code len} {@code char}s. 919 * 920 * @param index position at which to insert subarray. 921 * @param str A {@code char} array. 922 * @param offset the index of the first {@code char} in subarray to 923 * be inserted. 924 * @param len the number of {@code char}s in the subarray to 925 * be inserted. 926 * @return This object 927 * @throws StringIndexOutOfBoundsException if {@code index} 928 * is negative or greater than {@code length()}, or 929 * {@code offset} or {@code len} are negative, or 930 * {@code (offset+len)} is greater than 931 * {@code str.length}. 932 */ 933 public AbstractStringBuilder insert(int index, char[] str, int offset, 934 int len) 935 { 936 if ((index < 0) || (index > length())) 937 throw new StringIndexOutOfBoundsException(index); 938 if ((offset < 0) || (len < 0) || (offset > str.length - len)) 939 throw new StringIndexOutOfBoundsException( 940 "offset " + offset + ", len " + len + ", str.length " 941 + str.length); 942 ensureCapacityInternal(count + len); 943 System.arraycopy(value, index, value, index + len, count - index); 944 System.arraycopy(str, offset, value, index, len); 945 count += len; 946 return this; 947 } 948 949 /** 950 * Inserts the string representation of the {@code Object} 951 * argument into this character sequence. 952 * <p> 953 * The overall effect is exactly as if the second argument were 954 * converted to a string by the method {@link String#valueOf(Object)}, 955 * and the characters of that string were then 956 * {@link #insert(int,String) inserted} into this character 957 * sequence at the indicated offset. 958 * <p> 959 * The {@code offset} argument must be greater than or equal to 960 * {@code 0}, and less than or equal to the {@linkplain #length() length} 961 * of this sequence. 962 * 963 * @param offset the offset. 964 * @param obj an {@code Object}. 965 * @return a reference to this object. 966 * @throws StringIndexOutOfBoundsException if the offset is invalid. 967 */ 968 public AbstractStringBuilder insert(int offset, Object obj) { 969 return insert(offset, String.valueOf(obj)); 970 } 971 972 /** 973 * Inserts the string into this character sequence. 974 * <p> 975 * The characters of the {@code String} argument are inserted, in 976 * order, into this sequence at the indicated offset, moving up any 977 * characters originally above that position and increasing the length 978 * of this sequence by the length of the argument. If 979 * {@code str} is {@code null}, then the four characters 980 * {@code "null"} are inserted into this sequence. 981 * <p> 982 * The character at index <i>k</i> in the new character sequence is 983 * equal to: 984 * <ul> 985 * <li>the character at index <i>k</i> in the old character sequence, if 986 * <i>k</i> is less than {@code offset} 987 * <li>the character at index <i>k</i>{@code -offset} in the 988 * argument {@code str}, if <i>k</i> is not less than 989 * {@code offset} but is less than {@code offset+str.length()} 990 * <li>the character at index <i>k</i>{@code -str.length()} in the 991 * old character sequence, if <i>k</i> is not less than 992 * {@code offset+str.length()} 993 * </ul><p> 994 * The {@code offset} argument must be greater than or equal to 995 * {@code 0}, and less than or equal to the {@linkplain #length() length} 996 * of this sequence. 997 * 998 * @param offset the offset. 999 * @param str a string. 1000 * @return a reference to this object. 1001 * @throws StringIndexOutOfBoundsException if the offset is invalid. 1002 */ 1003 public AbstractStringBuilder insert(int offset, String str) { 1004 if ((offset < 0) || (offset > length())) 1005 throw new StringIndexOutOfBoundsException(offset); 1006 if (str == null) 1007 str = "null"; 1008 int len = str.length(); 1009 ensureCapacityInternal(count + len); 1010 System.arraycopy(value, offset, value, offset + len, count - offset); 1011 str.getChars(value, offset); 1012 count += len; 1013 return this; 1014 } 1015 1016 /** 1017 * Inserts the string representation of the {@code char} array 1018 * argument into this sequence. 1019 * <p> 1020 * The characters of the array argument are inserted into the 1021 * contents of this sequence at the position indicated by 1022 * {@code offset}. The length of this sequence increases by 1023 * the length of the argument. 1024 * <p> 1025 * The overall effect is exactly as if the second argument were 1026 * converted to a string by the method {@link String#valueOf(char[])}, 1027 * and the characters of that string were then 1028 * {@link #insert(int,String) inserted} into this character 1029 * sequence at the indicated offset. 1030 * <p> 1031 * The {@code offset} argument must be greater than or equal to 1032 * {@code 0}, and less than or equal to the {@linkplain #length() length} 1033 * of this sequence. 1034 * 1035 * @param offset the offset. 1036 * @param str a character array. 1037 * @return a reference to this object. 1038 * @throws StringIndexOutOfBoundsException if the offset is invalid. 1039 */ 1040 public AbstractStringBuilder insert(int offset, char[] str) { 1041 if ((offset < 0) || (offset > length())) 1042 throw new StringIndexOutOfBoundsException(offset); 1043 int len = str.length; 1044 ensureCapacityInternal(count + len); 1045 System.arraycopy(value, offset, value, offset + len, count - offset); 1046 System.arraycopy(str, 0, value, offset, len); 1047 count += len; 1048 return this; 1049 } 1050 1051 /** 1052 * Inserts the specified {@code CharSequence} into this sequence. 1053 * <p> 1054 * The characters of the {@code CharSequence} argument are inserted, 1055 * in order, into this sequence at the indicated offset, moving up 1056 * any characters originally above that position and increasing the length 1057 * of this sequence by the length of the argument s. 1058 * <p> 1059 * The result of this method is exactly the same as if it were an 1060 * invocation of this object's 1061 * {@link #insert(int,CharSequence,int,int) insert}(dstOffset, s, 0, s.length()) 1062 * method. 1063 * 1064 * <p>If {@code s} is {@code null}, then the four characters 1065 * {@code "null"} are inserted into this sequence. 1066 * 1067 * @param dstOffset the offset. 1068 * @param s the sequence to be inserted 1069 * @return a reference to this object. 1070 * @throws IndexOutOfBoundsException if the offset is invalid. 1071 */ 1072 public AbstractStringBuilder insert(int dstOffset, CharSequence s) { 1073 if (s == null) 1074 s = "null"; 1075 if (s instanceof String) 1076 return this.insert(dstOffset, (String)s); 1077 return this.insert(dstOffset, s, 0, s.length()); 1078 } 1079 1080 /** 1081 * Inserts a subsequence of the specified {@code CharSequence} into 1082 * this sequence. 1083 * <p> 1084 * The subsequence of the argument {@code s} specified by 1085 * {@code start} and {@code end} are inserted, 1086 * in order, into this sequence at the specified destination offset, moving 1087 * up any characters originally above that position. The length of this 1088 * sequence is increased by {@code end - start}. 1089 * <p> 1090 * The character at index <i>k</i> in this sequence becomes equal to: 1091 * <ul> 1092 * <li>the character at index <i>k</i> in this sequence, if 1093 * <i>k</i> is less than {@code dstOffset} 1094 * <li>the character at index <i>k</i>{@code +start-dstOffset} in 1095 * the argument {@code s}, if <i>k</i> is greater than or equal to 1096 * {@code dstOffset} but is less than {@code dstOffset+end-start} 1097 * <li>the character at index <i>k</i>{@code -(end-start)} in this 1098 * sequence, if <i>k</i> is greater than or equal to 1099 * {@code dstOffset+end-start} 1100 * </ul><p> 1101 * The {@code dstOffset} argument must be greater than or equal to 1102 * {@code 0}, and less than or equal to the {@linkplain #length() length} 1103 * of this sequence. 1104 * <p>The start argument must be nonnegative, and not greater than 1105 * {@code end}. 1106 * <p>The end argument must be greater than or equal to 1107 * {@code start}, and less than or equal to the length of s. 1108 * 1109 * <p>If {@code s} is {@code null}, then this method inserts 1110 * characters as if the s parameter was a sequence containing the four 1111 * characters {@code "null"}. 1112 * 1113 * @param dstOffset the offset in this sequence. 1114 * @param s the sequence to be inserted. 1115 * @param start the starting index of the subsequence to be inserted. 1116 * @param end the end index of the subsequence to be inserted. 1117 * @return a reference to this object. 1118 * @throws IndexOutOfBoundsException if {@code dstOffset} 1119 * is negative or greater than {@code this.length()}, or 1120 * {@code start} or {@code end} are negative, or 1121 * {@code start} is greater than {@code end} or 1122 * {@code end} is greater than {@code s.length()} 1123 */ 1124 public AbstractStringBuilder insert(int dstOffset, CharSequence s, 1125 int start, int end) { 1126 if (s == null) 1127 s = "null"; 1128 if ((dstOffset < 0) || (dstOffset > this.length())) 1129 throw new IndexOutOfBoundsException("dstOffset "+dstOffset); 1130 if ((start < 0) || (end < 0) || (start > end) || (end > s.length())) 1131 throw new IndexOutOfBoundsException( 1132 "start " + start + ", end " + end + ", s.length() " 1133 + s.length()); 1134 int len = end - start; 1135 ensureCapacityInternal(count + len); 1136 System.arraycopy(value, dstOffset, value, dstOffset + len, 1137 count - dstOffset); 1138 for (int i=start; i<end; i++) 1139 value[dstOffset++] = s.charAt(i); 1140 count += len; 1141 return this; 1142 } 1143 1144 /** 1145 * Inserts the string representation of the {@code boolean} 1146 * argument into this sequence. 1147 * <p> 1148 * The overall effect is exactly as if the second argument were 1149 * converted to a string by the method {@link String#valueOf(boolean)}, 1150 * and the characters of that string were then 1151 * {@link #insert(int,String) inserted} into this character 1152 * sequence at the indicated offset. 1153 * <p> 1154 * The {@code offset} argument must be greater than or equal to 1155 * {@code 0}, and less than or equal to the {@linkplain #length() length} 1156 * of this sequence. 1157 * 1158 * @param offset the offset. 1159 * @param b a {@code boolean}. 1160 * @return a reference to this object. 1161 * @throws StringIndexOutOfBoundsException if the offset is invalid. 1162 */ 1163 public AbstractStringBuilder insert(int offset, boolean b) { 1164 return insert(offset, String.valueOf(b)); 1165 } 1166 1167 /** 1168 * Inserts the string representation of the {@code char} 1169 * argument into this sequence. 1170 * <p> 1171 * The overall effect is exactly as if the second argument were 1172 * converted to a string by the method {@link String#valueOf(char)}, 1173 * and the character in that string were then 1174 * {@link #insert(int,String) inserted} into this character 1175 * sequence at the indicated offset. 1176 * <p> 1177 * The {@code offset} argument must be greater than or equal to 1178 * {@code 0}, and less than or equal to the {@linkplain #length() length} 1179 * of this sequence. 1180 * 1181 * @param offset the offset. 1182 * @param c a {@code char}. 1183 * @return a reference to this object. 1184 * @throws IndexOutOfBoundsException if the offset is invalid. 1185 */ 1186 public AbstractStringBuilder insert(int offset, char c) { 1187 ensureCapacityInternal(count + 1); 1188 System.arraycopy(value, offset, value, offset + 1, count - offset); 1189 value[offset] = c; 1190 count += 1; 1191 return this; 1192 } 1193 1194 /** 1195 * Inserts the string representation of the second {@code int} 1196 * argument into this sequence. 1197 * <p> 1198 * The overall effect is exactly as if the second argument were 1199 * converted to a string by the method {@link String#valueOf(int)}, 1200 * and the characters of that string were then 1201 * {@link #insert(int,String) inserted} into this character 1202 * sequence at the indicated offset. 1203 * <p> 1204 * The {@code offset} argument must be greater than or equal to 1205 * {@code 0}, and less than or equal to the {@linkplain #length() length} 1206 * of this sequence. 1207 * 1208 * @param offset the offset. 1209 * @param i an {@code int}. 1210 * @return a reference to this object. 1211 * @throws StringIndexOutOfBoundsException if the offset is invalid. 1212 */ 1213 public AbstractStringBuilder insert(int offset, int i) { 1214 return insert(offset, String.valueOf(i)); 1215 } 1216 1217 /** 1218 * Inserts the string representation of the {@code long} 1219 * argument into this sequence. 1220 * <p> 1221 * The overall effect is exactly as if the second argument were 1222 * converted to a string by the method {@link String#valueOf(long)}, 1223 * and the characters of that string were then 1224 * {@link #insert(int,String) inserted} into this character 1225 * sequence at the indicated offset. 1226 * <p> 1227 * The {@code offset} argument must be greater than or equal to 1228 * {@code 0}, and less than or equal to the {@linkplain #length() length} 1229 * of this sequence. 1230 * 1231 * @param offset the offset. 1232 * @param l a {@code long}. 1233 * @return a reference to this object. 1234 * @throws StringIndexOutOfBoundsException if the offset is invalid. 1235 */ 1236 public AbstractStringBuilder insert(int offset, long l) { 1237 return insert(offset, String.valueOf(l)); 1238 } 1239 1240 /** 1241 * Inserts the string representation of the {@code float} 1242 * argument into this sequence. 1243 * <p> 1244 * The overall effect is exactly as if the second argument were 1245 * converted to a string by the method {@link String#valueOf(float)}, 1246 * and the characters of that string were then 1247 * {@link #insert(int,String) inserted} into this character 1248 * sequence at the indicated offset. 1249 * <p> 1250 * The {@code offset} argument must be greater than or equal to 1251 * {@code 0}, and less than or equal to the {@linkplain #length() length} 1252 * of this sequence. 1253 * 1254 * @param offset the offset. 1255 * @param f a {@code float}. 1256 * @return a reference to this object. 1257 * @throws StringIndexOutOfBoundsException if the offset is invalid. 1258 */ 1259 public AbstractStringBuilder insert(int offset, float f) { 1260 return insert(offset, String.valueOf(f)); 1261 } 1262 1263 /** 1264 * Inserts the string representation of the {@code double} 1265 * argument into this sequence. 1266 * <p> 1267 * The overall effect is exactly as if the second argument were 1268 * converted to a string by the method {@link String#valueOf(double)}, 1269 * and the characters of that string were then 1270 * {@link #insert(int,String) inserted} into this character 1271 * sequence at the indicated offset. 1272 * <p> 1273 * The {@code offset} argument must be greater than or equal to 1274 * {@code 0}, and less than or equal to the {@linkplain #length() length} 1275 * of this sequence. 1276 * 1277 * @param offset the offset. 1278 * @param d a {@code double}. 1279 * @return a reference to this object. 1280 * @throws StringIndexOutOfBoundsException if the offset is invalid. 1281 */ 1282 public AbstractStringBuilder insert(int offset, double d) { 1283 return insert(offset, String.valueOf(d)); 1284 } 1285 1286 /** 1287 * Returns the index within this string of the first occurrence of the 1288 * specified substring. The integer returned is the smallest value 1289 * <i>k</i> such that: 1290 * <blockquote><pre> 1291 * this.toString().startsWith(str, <i>k</i>) 1292 * </pre></blockquote> 1293 * is {@code true}. 1294 * 1295 * @param str any string. 1296 * @return if the string argument occurs as a substring within this 1297 * object, then the index of the first character of the first 1298 * such substring is returned; if it does not occur as a 1299 * substring, {@code -1} is returned. 1300 */ 1301 public int indexOf(String str) { 1302 return indexOf(str, 0); 1303 } 1304 1305 /** 1306 * Returns the index within this string of the first occurrence of the 1307 * specified substring, starting at the specified index. The integer 1308 * returned is the smallest value {@code k} for which: 1309 * <blockquote><pre> 1310 * k >= Math.min(fromIndex, str.length()) && 1311 * this.toString().startsWith(str, k) 1312 * </pre></blockquote> 1313 * If no such value of <i>k</i> exists, then -1 is returned. 1314 * 1315 * @param str the substring for which to search. 1316 * @param fromIndex the index from which to start the search. 1317 * @return the index within this string of the first occurrence of the 1318 * specified substring, starting at the specified index. 1319 */ 1320 public int indexOf(String str, int fromIndex) { 1321 return String.indexOf(value, 0, count, str, fromIndex); 1322 } 1323 1324 /** 1325 * Returns the index within this string of the rightmost occurrence 1326 * of the specified substring. The rightmost empty string "" is 1327 * considered to occur at the index value {@code this.length()}. 1328 * The returned index is the largest value <i>k</i> such that 1329 * <blockquote><pre> 1330 * this.toString().startsWith(str, k) 1331 * </pre></blockquote> 1332 * is true. 1333 * 1334 * @param str the substring to search for. 1335 * @return if the string argument occurs one or more times as a substring 1336 * within this object, then the index of the first character of 1337 * the last such substring is returned. If it does not occur as 1338 * a substring, {@code -1} is returned. 1339 */ 1340 public int lastIndexOf(String str) { 1341 return lastIndexOf(str, count); 1342 } 1343 1344 /** 1345 * Returns the index within this string of the last occurrence of the 1346 * specified substring. The integer returned is the largest value <i>k</i> 1347 * such that: 1348 * <blockquote><pre> 1349 * k <= Math.min(fromIndex, str.length()) && 1350 * this.toString().startsWith(str, k) 1351 * </pre></blockquote> 1352 * If no such value of <i>k</i> exists, then -1 is returned. 1353 * 1354 * @param str the substring to search for. 1355 * @param fromIndex the index to start the search from. 1356 * @return the index within this sequence of the last occurrence of the 1357 * specified substring. 1358 */ 1359 public int lastIndexOf(String str, int fromIndex) { 1360 return String.lastIndexOf(value, 0, count, str, fromIndex); 1361 } 1362 1363 /** 1364 * Causes this character sequence to be replaced by the reverse of 1365 * the sequence. If there are any surrogate pairs included in the 1366 * sequence, these are treated as single characters for the 1367 * reverse operation. Thus, the order of the high-low surrogates 1368 * is never reversed. 1369 * 1370 * Let <i>n</i> be the character length of this character sequence 1371 * (not the length in {@code char} values) just prior to 1372 * execution of the {@code reverse} method. Then the 1373 * character at index <i>k</i> in the new character sequence is 1374 * equal to the character at index <i>n-k-1</i> in the old 1375 * character sequence. 1376 * 1377 * <p>Note that the reverse operation may result in producing 1378 * surrogate pairs that were unpaired low-surrogates and 1379 * high-surrogates before the operation. For example, reversing 1380 * "\u005CuDC00\u005CuD800" produces "\u005CuD800\u005CuDC00" which is 1381 * a valid surrogate pair. 1382 * 1383 * @return a reference to this object. 1384 */ 1385 public AbstractStringBuilder reverse() { 1386 boolean hasSurrogates = false; 1387 int n = count - 1; 1388 for (int j = (n-1) >> 1; j >= 0; j--) { 1389 int k = n - j; 1390 char cj = value[j]; 1391 char ck = value[k]; 1392 value[j] = ck; 1393 value[k] = cj; 1394 if (Character.isSurrogate(cj) || 1395 Character.isSurrogate(ck)) { 1396 hasSurrogates = true; 1397 } 1398 } 1399 if (hasSurrogates) { 1400 reverseAllValidSurrogatePairs(); 1401 } 1402 return this; 1403 } 1404 1405 /** Outlined helper method for reverse() */ 1406 private void reverseAllValidSurrogatePairs() { 1407 for (int i = 0; i < count - 1; i++) { 1408 char c2 = value[i]; 1409 if (Character.isLowSurrogate(c2)) { 1410 char c1 = value[i + 1]; 1411 if (Character.isHighSurrogate(c1)) { 1412 value[i++] = c1; 1413 value[i] = c2; 1414 } 1415 } 1416 } 1417 } 1418 1419 /** 1420 * Returns a string representing the data in this sequence. 1421 * A new {@code String} object is allocated and initialized to 1422 * contain the character sequence currently represented by this 1423 * object. This {@code String} is then returned. Subsequent 1424 * changes to this sequence do not affect the contents of the 1425 * {@code String}. 1426 * 1427 * @return a string representation of this sequence of characters. 1428 */ 1429 @Override 1430 public abstract String toString(); 1431 1432 /** 1433 * Needed by {@code String} for the contentEquals method. 1434 */ 1435 final char[] getValue() { 1436 return value; 1437 } 1438 1439 }