Source for java.lang.StringBuffer

   1: /* StringBuffer.java -- Growable strings
   2:    Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
   3:    Free Software Foundation, Inc.
   4: 
   5: This file is part of GNU Classpath.
   6: 
   7: GNU Classpath is free software; you can redistribute it and/or modify
   8: it under the terms of the GNU General Public License as published by
   9: the Free Software Foundation; either version 2, or (at your option)
  10: any later version.
  11: 
  12: GNU Classpath is distributed in the hope that it will be useful, but
  13: WITHOUT ANY WARRANTY; without even the implied warranty of
  14: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15: General Public License for more details.
  16: 
  17: You should have received a copy of the GNU General Public License
  18: along with GNU Classpath; see the file COPYING.  If not, write to the
  19: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  20: 02110-1301 USA.
  21: 
  22: Linking this library statically or dynamically with other modules is
  23: making a combined work based on this library.  Thus, the terms and
  24: conditions of the GNU General Public License cover the whole
  25: combination.
  26: 
  27: As a special exception, the copyright holders of this library give you
  28: permission to link this library with independent modules to produce an
  29: executable, regardless of the license terms of these independent
  30: modules, and to copy and distribute the resulting executable under
  31: terms of your choice, provided that you also meet, for each linked
  32: independent module, the terms and conditions of the license of that
  33: module.  An independent module is a module which is not derived from
  34: or based on this library.  If you modify this library, you may extend
  35: this exception to your version of the library, but you are not
  36: obligated to do so.  If you do not wish to do so, delete this
  37: exception statement from your version. */
  38: 
  39: package java.lang;
  40: 
  41: import java.io.Serializable;
  42: 
  43: /**
  44:  * <code>StringBuffer</code> represents a changeable <code>String</code>.
  45:  * It provides the operations required to modify the
  46:  * <code>StringBuffer</code>, including insert, replace, delete, append,
  47:  * and reverse. It is thread-safe; meaning that all modifications to a buffer
  48:  * are in synchronized methods.
  49:  *
  50:  * <p><code>StringBuffer</code>s are variable-length in nature, so even if
  51:  * you initialize them to a certain size, they can still grow larger than
  52:  * that. <em>Capacity</em> indicates the number of characters the
  53:  * <code>StringBuffer</code> can have in it before it has to grow (growing
  54:  * the char array is an expensive operation involving <code>new</code>).
  55:  *
  56:  * <p>Incidentally, compilers often implement the String operator "+"
  57:  * by using a <code>StringBuffer</code> operation:<br>
  58:  * <code>a + b</code><br>
  59:  * is the same as<br>
  60:  * <code>new StringBuffer().append(a).append(b).toString()</code>.
  61:  *
  62:  * <p>Classpath's StringBuffer is capable of sharing memory with Strings for
  63:  * efficiency.  This will help when a StringBuffer is converted to a String
  64:  * and the StringBuffer is not changed after that (quite common when performing
  65:  * string concatenation).
  66:  *
  67:  * @author Paul Fisher
  68:  * @author John Keiser
  69:  * @author Tom Tromey
  70:  * @author Eric Blake (ebb9@email.byu.edu)
  71:  * @see String
  72:  * @since 1.0
  73:  * @status updated to 1.4
  74:  */
  75: public final class StringBuffer implements Serializable, CharSequence
  76: {
  77:   /**
  78:    * Compatible with JDK 1.0+.
  79:    */
  80:   private static final long serialVersionUID = 3388685877147921107L;
  81: 
  82:   /**
  83:    * Index of next available character (and thus the size of the current
  84:    * string contents).  Note that this has permissions set this way so that
  85:    * String can get the value.
  86:    *
  87:    * @serial the number of characters in the buffer
  88:    */
  89:   int count;
  90: 
  91:   /**
  92:    * The buffer.  Note that this has permissions set this way so that String
  93:    * can get the value.
  94:    *
  95:    * @serial the buffer
  96:    */
  97:   char[] value;
  98: 
  99:   /**
 100:    * True if the buffer is shared with another object (StringBuffer or
 101:    * String); this means the buffer must be copied before writing to it again.
 102:    * Note that this has permissions set this way so that String can get the
 103:    * value.
 104:    *
 105:    * @serial whether the buffer is shared
 106:    */
 107:   boolean shared;
 108: 
 109:   /**
 110:    * The default capacity of a buffer.
 111:    */
 112:   private static final int DEFAULT_CAPACITY = 16;
 113: 
 114:   /**
 115:    * Create a new StringBuffer with default capacity 16.
 116:    */
 117:   public StringBuffer()
 118:   {
 119:     this(DEFAULT_CAPACITY);
 120:   }
 121: 
 122:   /**
 123:    * Create an empty <code>StringBuffer</code> with the specified initial
 124:    * capacity.
 125:    *
 126:    * @param capacity the initial capacity
 127:    * @throws NegativeArraySizeException if capacity is negative
 128:    */
 129:   public StringBuffer(int capacity)
 130:   {
 131:     value = new char[capacity];
 132:   }
 133: 
 134:   /**
 135:    * Create a new <code>StringBuffer</code> with the characters in the
 136:    * specified <code>String</code>. Initial capacity will be the size of the
 137:    * String plus 16.
 138:    *
 139:    * @param str the <code>String</code> to convert
 140:    * @throws NullPointerException if str is null
 141:    */
 142:   public StringBuffer(String str)
 143:   {
 144:     // Unfortunately, because the size is 16 larger, we cannot share.
 145:     count = str.count;
 146:     value = new char[count + DEFAULT_CAPACITY];
 147:     str.getChars(0, count, value, 0);
 148:   }
 149: 
 150:   /**
 151:    * Create a new <code>StringBuffer</code> with the characters from the
 152:    * specified <code>CharSequence</code>. Initial capacity will be the
 153:    * size of the CharSequence plus 16.
 154:    *
 155:    * @param sequence the <code>String</code> to convert
 156:    * @throws NullPointerException if str is null
 157:    *
 158:    * @since 1.5
 159:    */
 160:   public StringBuffer(CharSequence sequence)
 161:   {
 162:     count = Math.max(0, sequence.length());
 163:     value = new char[count + DEFAULT_CAPACITY];
 164:     for (int i = 0; i < count; ++i)
 165:       value[i] = sequence.charAt(i);
 166:   }
 167: 
 168:   /**
 169:    * Get the length of the <code>String</code> this <code>StringBuffer</code>
 170:    * would create. Not to be confused with the <em>capacity</em> of the
 171:    * <code>StringBuffer</code>.
 172:    *
 173:    * @return the length of this <code>StringBuffer</code>
 174:    * @see #capacity()
 175:    * @see #setLength(int)
 176:    */
 177:   public synchronized int length()
 178:   {
 179:     return count;
 180:   }
 181: 
 182:   /**
 183:    * Get the total number of characters this <code>StringBuffer</code> can
 184:    * support before it must be grown.  Not to be confused with <em>length</em>.
 185:    *
 186:    * @return the capacity of this <code>StringBuffer</code>
 187:    * @see #length()
 188:    * @see #ensureCapacity(int)
 189:    */
 190:   public synchronized int capacity()
 191:   {
 192:     return value.length;
 193:   }
 194: 
 195:   /**
 196:    * Increase the capacity of this <code>StringBuffer</code>. This will
 197:    * ensure that an expensive growing operation will not occur until
 198:    * <code>minimumCapacity</code> is reached. The buffer is grown to the
 199:    * larger of <code>minimumCapacity</code> and
 200:    * <code>capacity() * 2 + 2</code>, if it is not already large enough.
 201:    *
 202:    * @param minimumCapacity the new capacity
 203:    * @see #capacity()
 204:    */
 205:   public synchronized void ensureCapacity(int minimumCapacity)
 206:   {
 207:     ensureCapacity_unsynchronized(minimumCapacity);
 208:   }
 209: 
 210:   /**
 211:    * Set the length of this StringBuffer. If the new length is greater than
 212:    * the current length, all the new characters are set to '\0'. If the new
 213:    * length is less than the current length, the first <code>newLength</code>
 214:    * characters of the old array will be preserved, and the remaining
 215:    * characters are truncated.
 216:    *
 217:    * @param newLength the new length
 218:    * @throws IndexOutOfBoundsException if the new length is negative
 219:    *         (while unspecified, this is a StringIndexOutOfBoundsException)
 220:    * @see #length()
 221:    */
 222:   public synchronized void setLength(int newLength)
 223:   {
 224:     if (newLength < 0)
 225:       throw new StringIndexOutOfBoundsException(newLength);
 226: 
 227:     int valueLength = value.length;
 228: 
 229:     /* Always call ensureCapacity_unsynchronized in order to preserve
 230:        copy-on-write semantics.  */
 231:     ensureCapacity_unsynchronized(newLength);
 232: 
 233:     if (newLength < valueLength)
 234:       {
 235:         /* If the StringBuffer's value just grew, then we know that
 236:            value is newly allocated and the region between count and
 237:            newLength is filled with '\0'.  */
 238:     count = newLength;
 239:       }
 240:     else
 241:       {
 242:     /* The StringBuffer's value doesn't need to grow.  However,
 243:        we should clear out any cruft that may exist.  */
 244:     while (count < newLength)
 245:           value[count++] = '\0';
 246:       }
 247:   }
 248: 
 249:   /**
 250:    * Get the character at the specified index.
 251:    *
 252:    * @param index the index of the character to get, starting at 0
 253:    * @return the character at the specified index
 254:    * @throws IndexOutOfBoundsException if index is negative or &gt;= length()
 255:    */
 256:   public synchronized char charAt(int index)
 257:   {
 258:     if (index < 0 || index >= count)
 259:       throw new StringIndexOutOfBoundsException(index);
 260:     return value[index];
 261:   }
 262: 
 263:   /**
 264:    * Get the code point at the specified index.  This is like #charAt(int),
 265:    * but if the character is the start of a surrogate pair, and the
 266:    * following character completes the pair, then the corresponding
 267:    * supplementary code point is returned.
 268:    * @param index the index of the codepoint to get, starting at 0
 269:    * @return the codepoint at the specified index
 270:    * @throws IndexOutOfBoundsException if index is negative or &gt;= length()
 271:    * @since 1.5
 272:    */
 273:   public synchronized int codePointAt(int index)
 274:   {
 275:     return Character.codePointAt(value, index, count);
 276:   }
 277: 
 278:   /**
 279:    * Get the code point before the specified index.  This is like
 280:    * #codePointAt(int), but checks the characters at <code>index-1</code> and
 281:    * <code>index-2</code> to see if they form a supplementary code point.
 282:    * @param index the index just past the codepoint to get, starting at 0
 283:    * @return the codepoint at the specified index
 284:    * @throws IndexOutOfBoundsException if index is negative or &gt;= length()
 285:    * @since 1.5
 286:    */
 287:   public synchronized int codePointBefore(int index)
 288:   {
 289:     // Character.codePointBefore() doesn't perform this check.  We
 290:     // could use the CharSequence overload, but this is just as easy.
 291:     if (index >= count)
 292:       throw new IndexOutOfBoundsException();
 293:     return Character.codePointBefore(value, index, 1);
 294:   }
 295: 
 296:   /**
 297:    * Get the specified array of characters. <code>srcOffset - srcEnd</code>
 298:    * characters will be copied into the array you pass in.
 299:    *
 300:    * @param srcOffset the index to start copying from (inclusive)
 301:    * @param srcEnd the index to stop copying from (exclusive)
 302:    * @param dst the array to copy into
 303:    * @param dstOffset the index to start copying into
 304:    * @throws NullPointerException if dst is null
 305:    * @throws IndexOutOfBoundsException if any source or target indices are
 306:    *         out of range (while unspecified, source problems cause a
 307:    *         StringIndexOutOfBoundsException, and dest problems cause an
 308:    *         ArrayIndexOutOfBoundsException)
 309:    * @see System#arraycopy(Object, int, Object, int, int)
 310:    */
 311:   public synchronized void getChars(int srcOffset, int srcEnd,
 312:                                     char[] dst, int dstOffset)
 313:   {
 314:     if (srcOffset < 0 || srcEnd > count || srcEnd < srcOffset)
 315:       throw new StringIndexOutOfBoundsException();
 316:     System.arraycopy(value, srcOffset, dst, dstOffset, srcEnd - srcOffset);
 317:   }
 318: 
 319:   /**
 320:    * Set the character at the specified index.
 321:    *
 322:    * @param index the index of the character to set starting at 0
 323:    * @param ch the value to set that character to
 324:    * @throws IndexOutOfBoundsException if index is negative or &gt;= length()
 325:    *         (while unspecified, this is a StringIndexOutOfBoundsException)
 326:    */
 327:   public synchronized void setCharAt(int index, char ch)
 328:   {
 329:     if (index < 0 || index >= count)
 330:       throw new StringIndexOutOfBoundsException(index);
 331:     // Call ensureCapacity to enforce copy-on-write.
 332:     ensureCapacity_unsynchronized(count);
 333:     value[index] = ch;
 334:   }
 335: 
 336:   /**
 337:    * Append the <code>String</code> value of the argument to this
 338:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 339:    * to <code>String</code>.
 340:    *
 341:    * @param obj the <code>Object</code> to convert and append
 342:    * @return this <code>StringBuffer</code>
 343:    * @see String#valueOf(Object)
 344:    * @see #append(String)
 345:    */
 346:   public StringBuffer append(Object obj)
 347:   {
 348:     return append(obj == null ? "null" : obj.toString());
 349:   }
 350: 
 351:   /**
 352:    * Append the <code>String</code> to this <code>StringBuffer</code>. If
 353:    * str is null, the String "null" is appended.
 354:    *
 355:    * @param str the <code>String</code> to append
 356:    * @return this <code>StringBuffer</code>
 357:    */
 358:   public synchronized StringBuffer append(String str)
 359:   {
 360:     if (str == null)
 361:       str = "null";
 362:     int len = str.count;
 363:     ensureCapacity_unsynchronized(count + len);
 364:     str.getChars(0, len, value, count);
 365:     count += len;
 366:     return this;
 367:   }
 368: 
 369:   /**
 370:    * Append the <code>StringBuffer</code> value of the argument to this
 371:    * <code>StringBuffer</code>. This behaves the same as
 372:    * <code>append((Object) stringBuffer)</code>, except it is more efficient.
 373:    *
 374:    * @param stringBuffer the <code>StringBuffer</code> to convert and append
 375:    * @return this <code>StringBuffer</code>
 376:    * @see #append(Object)
 377:    * @since 1.4
 378:    */
 379:   public synchronized StringBuffer append(StringBuffer stringBuffer)
 380:   {
 381:     if (stringBuffer == null)
 382:       return append("null");
 383:     synchronized (stringBuffer)
 384:       {
 385:         int len = stringBuffer.count;
 386:         ensureCapacity_unsynchronized(count + len);
 387:         System.arraycopy(stringBuffer.value, 0, value, count, len);
 388:         count += len;
 389:       }
 390:     return this;
 391:   }
 392: 
 393:   /**
 394:    * Append the <code>CharSequence</code> value of the argument to this
 395:    * <code>StringBuffer</code>.
 396:    *
 397:    * @param sequence the <code>CharSequence</code> to append
 398:    * @return this <code>StringBuffer</code>
 399:    * @see #append(Object)
 400:    * @since 1.5
 401:    */
 402:   public synchronized StringBuffer append(CharSequence sequence)
 403:   {
 404:     if (sequence == null)
 405:       sequence = "null";
 406:     return append(sequence, 0, sequence.length());
 407:   }
 408: 
 409:   /**
 410:    * Append the specified subsequence of the <code>CharSequence</code>
 411:    * argument to this <code>StringBuffer</code>.
 412:    *
 413:    * @param sequence the <code>CharSequence</code> to append
 414:    * @param start the starting index
 415:    * @param end one past the ending index
 416:    * @return this <code>StringBuffer</code>
 417:    * @see #append(Object)
 418:    * @since 1.5
 419:    */
 420:   public synchronized StringBuffer append(CharSequence sequence,
 421:                       int start, int end)
 422:   {
 423:     if (sequence == null)
 424:       sequence = "null";
 425:     if (start < 0 || end < 0 || start > end || end > sequence.length())
 426:       throw new IndexOutOfBoundsException();
 427:     ensureCapacity_unsynchronized(this.count + end - start);
 428:     for (int i = start; i < end; ++i)
 429:       value[count++] = sequence.charAt(i);
 430:     return this;
 431:   }
 432: 
 433:   /**
 434:    * Append the <code>char</code> array to this <code>StringBuffer</code>.
 435:    * This is similar (but more efficient) than
 436:    * <code>append(new String(data))</code>, except in the case of null.
 437:    *
 438:    * @param data the <code>char[]</code> to append
 439:    * @return this <code>StringBuffer</code>
 440:    * @throws NullPointerException if <code>str</code> is <code>null</code>
 441:    * @see #append(char[], int, int)
 442:    */
 443:   public StringBuffer append(char[] data)
 444:   {
 445:     return append(data, 0, data.length);
 446:   }
 447: 
 448:   /**
 449:    * Append part of the <code>char</code> array to this
 450:    * <code>StringBuffer</code>. This is similar (but more efficient) than
 451:    * <code>append(new String(data, offset, count))</code>, except in the case
 452:    * of null.
 453:    *
 454:    * @param data the <code>char[]</code> to append
 455:    * @param offset the start location in <code>str</code>
 456:    * @param count the number of characters to get from <code>str</code>
 457:    * @return this <code>StringBuffer</code>
 458:    * @throws NullPointerException if <code>str</code> is <code>null</code>
 459:    * @throws IndexOutOfBoundsException if offset or count is out of range
 460:    *         (while unspecified, this is a StringIndexOutOfBoundsException)
 461:    */
 462:   public synchronized StringBuffer append(char[] data, int offset, int count)
 463:   {
 464:     if (offset < 0 || count < 0 || offset > data.length - count)
 465:       throw new StringIndexOutOfBoundsException();
 466:     ensureCapacity_unsynchronized(this.count + count);
 467:     System.arraycopy(data, offset, value, this.count, count);
 468:     this.count += count;
 469:     return this;
 470:   }
 471: 
 472:   /**
 473:    * Append the <code>String</code> value of the argument to this
 474:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 475:    * to <code>String</code>.
 476:    *
 477:    * @param bool the <code>boolean</code> to convert and append
 478:    * @return this <code>StringBuffer</code>
 479:    * @see String#valueOf(boolean)
 480:    */
 481:   public StringBuffer append(boolean bool)
 482:   {
 483:     return append(bool ? "true" : "false");
 484:   }
 485: 
 486:   /**
 487:    * Append the <code>char</code> to this <code>StringBuffer</code>.
 488:    *
 489:    * @param ch the <code>char</code> to append
 490:    * @return this <code>StringBuffer</code>
 491:    */
 492:   public synchronized StringBuffer append(char ch)
 493:   {
 494:     ensureCapacity_unsynchronized(count + 1);
 495:     value[count++] = ch;
 496:     return this;
 497:   }
 498: 
 499:   /**
 500:    * Append the code point to this <code>StringBuffer</code>.
 501:    * This is like #append(char), but will append two characters
 502:    * if a supplementary code point is given.
 503:    *
 504:    * @param code the code point to append
 505:    * @return this <code>StringBuffer</code>
 506:    * @see Character#toChars(int, char[], int)
 507:    * @since 1.5
 508:    */
 509:   public synchronized StringBuffer appendCodePoint(int code)
 510:   {
 511:     int len = Character.charCount(code);
 512:     ensureCapacity_unsynchronized(count + len);
 513:     Character.toChars(code, value, count);
 514:     count += len;
 515:     return this;
 516:   }
 517: 
 518:   /**
 519:    * Append the <code>String</code> value of the argument to this
 520:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 521:    * to <code>String</code>.
 522:    *
 523:    * @param inum the <code>int</code> to convert and append
 524:    * @return this <code>StringBuffer</code>
 525:    * @see String#valueOf(int)
 526:    */
 527:   // GCJ LOCAL: this is native for efficiency.
 528:   public native StringBuffer append (int inum);
 529: 
 530:   /**
 531:    * Append the <code>String</code> value of the argument to this
 532:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 533:    * to <code>String</code>.
 534:    *
 535:    * @param lnum the <code>long</code> to convert and append
 536:    * @return this <code>StringBuffer</code>
 537:    * @see String#valueOf(long)
 538:    */
 539:   public StringBuffer append(long lnum)
 540:   {
 541:     return append(Long.toString(lnum, 10));
 542:   }
 543: 
 544:   /**
 545:    * Append the <code>String</code> value of the argument to this
 546:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 547:    * to <code>String</code>.
 548:    *
 549:    * @param fnum the <code>float</code> to convert and append
 550:    * @return this <code>StringBuffer</code>
 551:    * @see String#valueOf(float)
 552:    */
 553:   public StringBuffer append(float fnum)
 554:   {
 555:     return append(Float.toString(fnum));
 556:   }
 557: 
 558:   /**
 559:    * Append the <code>String</code> value of the argument to this
 560:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 561:    * to <code>String</code>.
 562:    *
 563:    * @param dnum the <code>double</code> to convert and append
 564:    * @return this <code>StringBuffer</code>
 565:    * @see String#valueOf(double)
 566:    */
 567:   public StringBuffer append(double dnum)
 568:   {
 569:     return append(Double.toString(dnum));
 570:   }
 571: 
 572:   /**
 573:    * Delete characters from this <code>StringBuffer</code>.
 574:    * <code>delete(10, 12)</code> will delete 10 and 11, but not 12. It is
 575:    * harmless for end to be larger than length().
 576:    *
 577:    * @param start the first character to delete
 578:    * @param end the index after the last character to delete
 579:    * @return this <code>StringBuffer</code>
 580:    * @throws StringIndexOutOfBoundsException if start or end are out of bounds
 581:    * @since 1.2
 582:    */
 583:   public synchronized StringBuffer delete(int start, int end)
 584:   {
 585:     if (start < 0 || start > count || start > end)
 586:       throw new StringIndexOutOfBoundsException(start);
 587:     if (end > count)
 588:       end = count;
 589:     // This will unshare if required.
 590:     ensureCapacity_unsynchronized(count);
 591:     if (count - end != 0)
 592:       System.arraycopy(value, end, value, start, count - end);
 593:     count -= end - start;
 594:     return this;
 595:   }
 596: 
 597:   /**
 598:    * Delete a character from this <code>StringBuffer</code>.
 599:    *
 600:    * @param index the index of the character to delete
 601:    * @return this <code>StringBuffer</code>
 602:    * @throws StringIndexOutOfBoundsException if index is out of bounds
 603:    * @since 1.2
 604:    */
 605:   public StringBuffer deleteCharAt(int index)
 606:   {
 607:     return delete(index, index + 1);
 608:   }
 609: 
 610:   /**
 611:    * Replace characters between index <code>start</code> (inclusive) and
 612:    * <code>end</code> (exclusive) with <code>str</code>. If <code>end</code>
 613:    * is larger than the size of this StringBuffer, all characters after
 614:    * <code>start</code> are replaced.
 615:    *
 616:    * @param start the beginning index of characters to delete (inclusive)
 617:    * @param end the ending index of characters to delete (exclusive)
 618:    * @param str the new <code>String</code> to insert
 619:    * @return this <code>StringBuffer</code>
 620:    * @throws StringIndexOutOfBoundsException if start or end are out of bounds
 621:    * @throws NullPointerException if str is null
 622:    * @since 1.2
 623:    */
 624:   public synchronized StringBuffer replace(int start, int end, String str)
 625:   {
 626:     if (start < 0 || start > count || start > end)
 627:       throw new StringIndexOutOfBoundsException(start);
 628: 
 629:     int len = str.count;
 630:     // Calculate the difference in 'count' after the replace.
 631:     int delta = len - (end > count ? count : end) + start;
 632:     ensureCapacity_unsynchronized(count + delta);
 633: 
 634:     if (delta != 0 && end < count)
 635:       System.arraycopy(value, end, value, end + delta, count - end);
 636: 
 637:     str.getChars(0, len, value, start);
 638:     count += delta;
 639:     return this;
 640:   }
 641: 
 642:   /**
 643:    * Creates a substring of this StringBuffer, starting at a specified index
 644:    * and ending at the end of this StringBuffer.
 645:    *
 646:    * @param beginIndex index to start substring (base 0)
 647:    * @return new String which is a substring of this StringBuffer
 648:    * @throws StringIndexOutOfBoundsException if beginIndex is out of bounds
 649:    * @see #substring(int, int)
 650:    * @since 1.2
 651:    */
 652:   public String substring(int beginIndex)
 653:   {
 654:     return substring(beginIndex, count);
 655:   }
 656: 
 657:   /**
 658:    * Creates a substring of this StringBuffer, starting at a specified index
 659:    * and ending at one character before a specified index. This is implemented
 660:    * the same as <code>substring(beginIndex, endIndex)</code>, to satisfy
 661:    * the CharSequence interface.
 662:    *
 663:    * @param beginIndex index to start at (inclusive, base 0)
 664:    * @param endIndex index to end at (exclusive)
 665:    * @return new String which is a substring of this StringBuffer
 666:    * @throws IndexOutOfBoundsException if beginIndex or endIndex is out of
 667:    *         bounds
 668:    * @see #substring(int, int)
 669:    * @since 1.4
 670:    */
 671:   public CharSequence subSequence(int beginIndex, int endIndex)
 672:   {
 673:     return substring(beginIndex, endIndex);
 674:   }
 675: 
 676:   /**
 677:    * Creates a substring of this StringBuffer, starting at a specified index
 678:    * and ending at one character before a specified index.
 679:    *
 680:    * @param beginIndex index to start at (inclusive, base 0)
 681:    * @param endIndex index to end at (exclusive)
 682:    * @return new String which is a substring of this StringBuffer
 683:    * @throws StringIndexOutOfBoundsException if beginIndex or endIndex is out
 684:    *         of bounds
 685:    * @since 1.2
 686:    */
 687:   public synchronized String substring(int beginIndex, int endIndex)
 688:   {
 689:     int len = endIndex - beginIndex;
 690:     if (beginIndex < 0 || endIndex > count || endIndex < beginIndex)
 691:       throw new StringIndexOutOfBoundsException();
 692:     if (len == 0)
 693:       return "";
 694:     // Don't copy unless substring is smaller than 1/4 of the buffer.
 695:     boolean share_buffer = ((len << 2) >= value.length);
 696:     if (share_buffer)
 697:       this.shared = true;
 698:     // Package constructor avoids an array copy.
 699:     return new String(value, beginIndex, len, share_buffer);
 700:   }
 701: 
 702:   /**
 703:    * Insert a subarray of the <code>char[]</code> argument into this
 704:    * <code>StringBuffer</code>.
 705:    *
 706:    * @param offset the place to insert in this buffer
 707:    * @param str the <code>char[]</code> to insert
 708:    * @param str_offset the index in <code>str</code> to start inserting from
 709:    * @param len the number of characters to insert
 710:    * @return this <code>StringBuffer</code>
 711:    * @throws NullPointerException if <code>str</code> is <code>null</code>
 712:    * @throws StringIndexOutOfBoundsException if any index is out of bounds
 713:    * @since 1.2
 714:    */
 715:   public synchronized StringBuffer insert(int offset,
 716:                                           char[] str, int str_offset, int len)
 717:   {
 718:     if (offset < 0 || offset > count || len < 0
 719:         || str_offset < 0 || str_offset > str.length - len)
 720:       throw new StringIndexOutOfBoundsException();
 721:     ensureCapacity_unsynchronized(count + len);
 722:     System.arraycopy(value, offset, value, offset + len, count - offset);
 723:     System.arraycopy(str, str_offset, value, offset, len);
 724:     count += len;
 725:     return this;
 726:   }
 727: 
 728:   /**
 729:    * Insert the <code>String</code> value of the argument into this
 730:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 731:    * to <code>String</code>.
 732:    *
 733:    * @param offset the place to insert in this buffer
 734:    * @param obj the <code>Object</code> to convert and insert
 735:    * @return this <code>StringBuffer</code>
 736:    * @exception StringIndexOutOfBoundsException if offset is out of bounds
 737:    * @see String#valueOf(Object)
 738:    */
 739:   public StringBuffer insert(int offset, Object obj)
 740:   {
 741:     return insert(offset, obj == null ? "null" : obj.toString());
 742:   }
 743: 
 744:   /**
 745:    * Insert the <code>String</code> argument into this
 746:    * <code>StringBuffer</code>. If str is null, the String "null" is used
 747:    * instead.
 748:    *
 749:    * @param offset the place to insert in this buffer
 750:    * @param str the <code>String</code> to insert
 751:    * @return this <code>StringBuffer</code>
 752:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 753:    */
 754:   public synchronized StringBuffer insert(int offset, String str)
 755:   {
 756:     if (offset < 0 || offset > count)
 757:       throw new StringIndexOutOfBoundsException(offset);
 758:     if (str == null)
 759:       str = "null";
 760:     int len = str.count;
 761:     ensureCapacity_unsynchronized(count + len);
 762:     System.arraycopy(value, offset, value, offset + len, count - offset);
 763:     str.getChars(0, len, value, offset);
 764:     count += len;
 765:     return this;
 766:   }
 767: 
 768:   /**
 769:    * Insert the <code>CharSequence</code> argument into this
 770:    * <code>StringBuffer</code>.  If the sequence is null, the String
 771:    * "null" is used instead.
 772:    *
 773:    * @param offset the place to insert in this buffer
 774:    * @param sequence the <code>CharSequence</code> to insert
 775:    * @return this <code>StringBuffer</code>
 776:    * @throws IndexOutOfBoundsException if offset is out of bounds
 777:    * @since 1.5
 778:    */
 779:   public synchronized StringBuffer insert(int offset, CharSequence sequence)
 780:   {
 781:     if (sequence == null)
 782:       sequence = "null";
 783:     return insert(offset, sequence, 0, sequence.length());
 784:   }
 785: 
 786:   /**
 787:    * Insert a subsequence of the <code>CharSequence</code> argument into this
 788:    * <code>StringBuffer</code>.  If the sequence is null, the String
 789:    * "null" is used instead.
 790:    *
 791:    * @param offset the place to insert in this buffer
 792:    * @param sequence the <code>CharSequence</code> to insert
 793:    * @param start the starting index of the subsequence
 794:    * @param end one past the ending index of the subsequence
 795:    * @return this <code>StringBuffer</code>
 796:    * @throws IndexOutOfBoundsException if offset, start,
 797:    * or end are out of bounds
 798:    * @since 1.5
 799:    */
 800:   public synchronized StringBuffer insert(int offset, CharSequence sequence,
 801:                       int start, int end)
 802:   {
 803:     if (sequence == null)
 804:       sequence = "null";
 805:     if (start < 0 || end < 0 || start > end || end > sequence.length())
 806:       throw new IndexOutOfBoundsException();
 807:     int len = end - start;
 808:     ensureCapacity_unsynchronized(count + len);
 809:     System.arraycopy(value, offset, value, offset + len, count - offset);
 810:     for (int i = start; i < end; ++i)
 811:       value[offset++] = sequence.charAt(i);
 812:     count += len;
 813:     return this;
 814:   }
 815: 
 816:   /**
 817:    * Insert the <code>char[]</code> argument into this
 818:    * <code>StringBuffer</code>.
 819:    *
 820:    * @param offset the place to insert in this buffer
 821:    * @param data the <code>char[]</code> to insert
 822:    * @return this <code>StringBuffer</code>
 823:    * @throws NullPointerException if <code>data</code> is <code>null</code>
 824:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 825:    * @see #insert(int, char[], int, int)
 826:    */
 827:   public StringBuffer insert(int offset, char[] data)
 828:   {
 829:     return insert(offset, data, 0, data.length);
 830:   }
 831: 
 832:   /**
 833:    * Insert the <code>String</code> value of the argument into this
 834:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 835:    * to <code>String</code>.
 836:    *
 837:    * @param offset the place to insert in this buffer
 838:    * @param bool the <code>boolean</code> to convert and insert
 839:    * @return this <code>StringBuffer</code>
 840:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 841:    * @see String#valueOf(boolean)
 842:    */
 843:   public StringBuffer insert(int offset, boolean bool)
 844:   {
 845:     return insert(offset, bool ? "true" : "false");
 846:   }
 847: 
 848:   /**
 849:    * Insert the <code>char</code> argument into this <code>StringBuffer</code>.
 850:    *
 851:    * @param offset the place to insert in this buffer
 852:    * @param ch the <code>char</code> to insert
 853:    * @return this <code>StringBuffer</code>
 854:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 855:    */
 856:   public synchronized StringBuffer insert(int offset, char ch)
 857:   {
 858:     if (offset < 0 || offset > count)
 859:       throw new StringIndexOutOfBoundsException(offset);
 860:     ensureCapacity_unsynchronized(count + 1);
 861:     System.arraycopy(value, offset, value, offset + 1, count - offset);
 862:     value[offset] = ch;
 863:     count++;
 864:     return this;
 865:   }
 866: 
 867:   /**
 868:    * Insert the <code>String</code> value of the argument into this
 869:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 870:    * to <code>String</code>.
 871:    *
 872:    * @param offset the place to insert in this buffer
 873:    * @param inum the <code>int</code> to convert and insert
 874:    * @return this <code>StringBuffer</code>
 875:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 876:    * @see String#valueOf(int)
 877:    */
 878:   public StringBuffer insert(int offset, int inum)
 879:   {
 880:     return insert(offset, String.valueOf(inum));
 881:   }
 882: 
 883:   /**
 884:    * Insert the <code>String</code> value of the argument into this
 885:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 886:    * to <code>String</code>.
 887:    *
 888:    * @param offset the place to insert in this buffer
 889:    * @param lnum the <code>long</code> to convert and insert
 890:    * @return this <code>StringBuffer</code>
 891:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 892:    * @see String#valueOf(long)
 893:    */
 894:   public StringBuffer insert(int offset, long lnum)
 895:   {
 896:     return insert(offset, Long.toString(lnum, 10));
 897:   }
 898: 
 899:   /**
 900:    * Insert the <code>String</code> value of the argument into this
 901:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 902:    * to <code>String</code>.
 903:    *
 904:    * @param offset the place to insert in this buffer
 905:    * @param fnum the <code>float</code> to convert and insert
 906:    * @return this <code>StringBuffer</code>
 907:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 908:    * @see String#valueOf(float)
 909:    */
 910:   public StringBuffer insert(int offset, float fnum)
 911:   {
 912:     return insert(offset, Float.toString(fnum));
 913:   }
 914: 
 915:   /**
 916:    * Insert the <code>String</code> value of the argument into this
 917:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 918:    * to <code>String</code>.
 919:    *
 920:    * @param offset the place to insert in this buffer
 921:    * @param dnum the <code>double</code> to convert and insert
 922:    * @return this <code>StringBuffer</code>
 923:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 924:    * @see String#valueOf(double)
 925:    */
 926:   public StringBuffer insert(int offset, double dnum)
 927:   {
 928:     return insert(offset, Double.toString(dnum));
 929:   }
 930: 
 931:   /**
 932:    * Finds the first instance of a substring in this StringBuffer.
 933:    *
 934:    * @param str String to find
 935:    * @return location (base 0) of the String, or -1 if not found
 936:    * @throws NullPointerException if str is null
 937:    * @see #indexOf(String, int)
 938:    * @since 1.4
 939:    */
 940:   public int indexOf(String str)
 941:   {
 942:     return indexOf(str, 0);
 943:   }
 944: 
 945:   /**
 946:    * Finds the first instance of a String in this StringBuffer, starting at
 947:    * a given index.  If starting index is less than 0, the search starts at
 948:    * the beginning of this String.  If the starting index is greater than the
 949:    * length of this String, or the substring is not found, -1 is returned.
 950:    *
 951:    * @param str String to find
 952:    * @param fromIndex index to start the search
 953:    * @return location (base 0) of the String, or -1 if not found
 954:    * @throws NullPointerException if str is null
 955:    * @since 1.4
 956:    */
 957:   public synchronized int indexOf(String str, int fromIndex)
 958:   {
 959:     if (fromIndex < 0)
 960:       fromIndex = 0;
 961:     int limit = count - str.count;
 962:     for ( ; fromIndex <= limit; fromIndex++)
 963:       if (regionMatches(fromIndex, str))
 964:         return fromIndex;
 965:     return -1;
 966:   }
 967: 
 968:   /**
 969:    * Finds the last instance of a substring in this StringBuffer.
 970:    *
 971:    * @param str String to find
 972:    * @return location (base 0) of the String, or -1 if not found
 973:    * @throws NullPointerException if str is null
 974:    * @see #lastIndexOf(String, int)
 975:    * @since 1.4
 976:    */
 977:   public int lastIndexOf(String str)
 978:   {
 979:     return lastIndexOf(str, count - str.count);
 980:   }
 981: 
 982:   /**
 983:    * Finds the last instance of a String in this StringBuffer, starting at a
 984:    * given index.  If starting index is greater than the maximum valid index,
 985:    * then the search begins at the end of this String.  If the starting index
 986:    * is less than zero, or the substring is not found, -1 is returned.
 987:    *
 988:    * @param str String to find
 989:    * @param fromIndex index to start the search
 990:    * @return location (base 0) of the String, or -1 if not found
 991:    * @throws NullPointerException if str is null
 992:    * @since 1.4
 993:    */
 994:   public synchronized int lastIndexOf(String str, int fromIndex)
 995:   {
 996:     fromIndex = Math.min(fromIndex, count - str.count);
 997:     for ( ; fromIndex >= 0; fromIndex--)
 998:       if (regionMatches(fromIndex, str))
 999:         return fromIndex;
1000:     return -1;
1001:   }
1002: 
1003:   /**
1004:    * Reverse the characters in this StringBuffer. The same sequence of
1005:    * characters exists, but in the reverse index ordering.
1006:    *
1007:    * @return this <code>StringBuffer</code>
1008:    */
1009:   public synchronized StringBuffer reverse()
1010:   {
1011:     // Call ensureCapacity to enforce copy-on-write.
1012:     ensureCapacity_unsynchronized(count);
1013:     for (int i = count >> 1, j = count - i; --i >= 0; ++j)
1014:       {
1015:         char c = value[i];
1016:         value[i] = value[j];
1017:         value[j] = c;
1018:       }
1019:     return this;
1020:   }
1021: 
1022:   /**
1023:    * Convert this <code>StringBuffer</code> to a <code>String</code>. The
1024:    * String is composed of the characters currently in this StringBuffer. Note
1025:    * that the result is a copy, and that future modifications to this buffer
1026:    * do not affect the String.
1027:    *
1028:    * @return the characters in this StringBuffer
1029:    */
1030:   public String toString()
1031:   {
1032:     // The string will set this.shared = true.
1033:     return new String(this);
1034:   }
1035: 
1036:   /**
1037:    * This may reduce the amount of memory used by the StringBuffer,
1038:    * by resizing the internal array to remove unused space.  However,
1039:    * this method is not required to resize, so this behavior cannot
1040:    * be relied upon.
1041:    * @since 1.5
1042:    */
1043:   public synchronized void trimToSize()
1044:   {
1045:     int wouldSave = value.length - count;
1046:     // Some random heuristics: if we save less than 20 characters, who
1047:     // cares.
1048:     if (wouldSave < 20)
1049:       return;
1050:     // If we save more than 200 characters, shrink.
1051:     // If we save more than 1/4 of the buffer, shrink.
1052:     if (wouldSave > 200 || wouldSave * 4 > value.length)
1053:       {
1054:     char[] newValue = new char[count];
1055:     System.arraycopy(value, 0, newValue, 0, count);
1056:     value = newValue;
1057:       }
1058:   }
1059: 
1060:   /**
1061:    * Return the number of code points between two indices in the
1062:    * <code>StringBuffer</code>.  An unpaired surrogate counts as a
1063:    * code point for this purpose.  Characters outside the indicated
1064:    * range are not examined, even if the range ends in the middle of a
1065:    * surrogate pair.
1066:    *
1067:    * @param start the starting index
1068:    * @param end one past the ending index
1069:    * @return the number of code points
1070:    * @since 1.5
1071:    */
1072:   public synchronized int codePointCount(int start, int end)
1073:   {
1074:     if (start < 0 || end >= count || start > end)
1075:       throw new StringIndexOutOfBoundsException();
1076: 
1077:     int count = 0;
1078:     while (start < end)
1079:       {
1080:     char base = value[start];
1081:     if (base < Character.MIN_HIGH_SURROGATE
1082:         || base > Character.MAX_HIGH_SURROGATE
1083:         || start == end
1084:         || start == count
1085:         || value[start + 1] < Character.MIN_LOW_SURROGATE
1086:         || value[start + 1] > Character.MAX_LOW_SURROGATE)
1087:       {
1088:         // Nothing.
1089:       }
1090:     else
1091:       {
1092:         // Surrogate pair.
1093:         ++start;
1094:       }
1095:     ++start;
1096:     ++count;
1097:       }
1098:     return count;
1099:   }
1100: 
1101:   /**
1102:    * Starting at the given index, this counts forward by the indicated
1103:    * number of code points, and then returns the resulting index.  An
1104:    * unpaired surrogate counts as a single code point for this
1105:    * purpose.
1106:    *
1107:    * @param start the starting index
1108:    * @param codePoints the number of code points
1109:    * @return the resulting index
1110:    * @since 1.5
1111:    */
1112:   public synchronized int offsetByCodePoints(int start, int codePoints)
1113:   {
1114:     while (codePoints > 0)
1115:       {
1116:     char base = value[start];
1117:     if (base < Character.MIN_HIGH_SURROGATE
1118:         || base > Character.MAX_HIGH_SURROGATE
1119:         || start == count
1120:         || value[start + 1] < Character.MIN_LOW_SURROGATE
1121:         || value[start + 1] > Character.MAX_LOW_SURROGATE)
1122:       {
1123:         // Nothing.
1124:       }
1125:     else
1126:       {
1127:         // Surrogate pair.
1128:         ++start;
1129:       }
1130:     ++start;
1131:     --codePoints;
1132:       }
1133:     return start;
1134:   }
1135: 
1136:   /**
1137:    * An unsynchronized version of ensureCapacity, used internally to avoid
1138:    * the cost of a second lock on the same object. This also has the side
1139:    * effect of duplicating the array, if it was shared (to form copy-on-write
1140:    * semantics).
1141:    *
1142:    * @param minimumCapacity the minimum capacity
1143:    * @see #ensureCapacity(int)
1144:    */
1145:   private void ensureCapacity_unsynchronized(int minimumCapacity)
1146:   {
1147:     if (shared || minimumCapacity > value.length)
1148:       {
1149:         // We don't want to make a larger vector when `shared' is
1150:         // set.  If we do, then setLength becomes very inefficient
1151:         // when repeatedly reusing a StringBuffer in a loop.
1152:         int max = (minimumCapacity > value.length
1153:                    ? value.length * 2 + 2
1154:                    : value.length);
1155:         minimumCapacity = (minimumCapacity < max ? max : minimumCapacity);
1156:         char[] nb = new char[minimumCapacity];
1157:         System.arraycopy(value, 0, nb, 0, count);
1158:         value = nb;
1159:         shared = false;
1160:       }
1161:   }
1162: 
1163:   /**
1164:    * Predicate which determines if a substring of this matches another String
1165:    * starting at a specified offset for each String and continuing for a
1166:    * specified length. This is more efficient than creating a String to call
1167:    * indexOf on.
1168:    *
1169:    * @param toffset index to start comparison at for this String
1170:    * @param other non-null String to compare to region of this
1171:    * @return true if regions match, false otherwise
1172:    * @see #indexOf(String, int)
1173:    * @see #lastIndexOf(String, int)
1174:    * @see String#regionMatches(boolean, int, String, int, int)
1175:    */
1176:   // GCJ LOCAL: native for gcj.
1177:   private native boolean regionMatches(int toffset, String other);
1178: }