Source for java.lang.StringBuffer

   1: /* StringBuffer.java -- Growable strings
   2:    Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
   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
  76:   implements Serializable, CharSequence, Appendable
  77: {
  78:   // Implementation note: if you change this class, you usually will
  79:   // want to change StringBuilder as well.
  80: 
  81:   /**
  82:    * Compatible with JDK 1.0+.
  83:    */
  84:   private static final long serialVersionUID = 3388685877147921107L;
  85: 
  86:   /**
  87:    * Index of next available character (and thus the size of the current
  88:    * string contents).  Note that this has permissions set this way so that
  89:    * String can get the value.
  90:    *
  91:    * @serial the number of characters in the buffer
  92:    */
  93:   int count;
  94: 
  95:   /**
  96:    * The buffer.  Note that this has permissions set this way so that String
  97:    * can get the value.
  98:    *
  99:    * @serial the buffer
 100:    */
 101:   char[] value;
 102: 
 103:   /**
 104:    * True if the buffer is shared with another object (StringBuffer or
 105:    * String); this means the buffer must be copied before writing to it again.
 106:    * Note that this has permissions set this way so that String can get the
 107:    * value.
 108:    *
 109:    * @serial whether the buffer is shared
 110:    */
 111:   boolean shared;
 112: 
 113:   /**
 114:    * The default capacity of a buffer.
 115:    */
 116:   private static final int DEFAULT_CAPACITY = 16;
 117: 
 118:   /**
 119:    * Create a new StringBuffer with default capacity 16.
 120:    */
 121:   public StringBuffer()
 122:   {
 123:     this(DEFAULT_CAPACITY);
 124:   }
 125: 
 126:   /**
 127:    * Create an empty <code>StringBuffer</code> with the specified initial
 128:    * capacity.
 129:    *
 130:    * @param capacity the initial capacity
 131:    * @throws NegativeArraySizeException if capacity is negative
 132:    */
 133:   public StringBuffer(int capacity)
 134:   {
 135:     value = new char[capacity];
 136:   }
 137: 
 138:   /**
 139:    * Create a new <code>StringBuffer</code> with the characters in the
 140:    * specified <code>String</code>. Initial capacity will be the size of the
 141:    * String plus 16.
 142:    *
 143:    * @param str the <code>String</code> to convert
 144:    * @throws NullPointerException if str is null
 145:    */
 146:   public StringBuffer(String str)
 147:   {
 148:     // Unfortunately, because the size is 16 larger, we cannot share.
 149:     count = str.count;
 150:     value = new char[count + DEFAULT_CAPACITY];
 151:     str.getChars(0, count, value, 0);
 152:   }
 153: 
 154:   /**
 155:    * Create a new <code>StringBuffer</code> with the characters in the
 156:    * specified <code>CharSequence</code>. Initial capacity will be the
 157:    * length of the sequence plus 16; if the sequence reports a length
 158:    * less than or equal to 0, then the initial capacity will be 16.
 159:    *
 160:    * @param seq the initializing <code>CharSequence</code>
 161:    * @throws NullPointerException if str is null
 162:    * @since 1.5
 163:    */
 164:   public StringBuffer(CharSequence seq)
 165:   {
 166:     int len = seq.length();
 167:     count = len <= 0 ? 0 : len;
 168:     value = new char[count + DEFAULT_CAPACITY];
 169:     for (int i = 0; i < len; ++i)
 170:       value[i] = seq.charAt(i);
 171:   }
 172: 
 173:   /**
 174:    * Get the length of the <code>String</code> this <code>StringBuffer</code>
 175:    * would create. Not to be confused with the <em>capacity</em> of the
 176:    * <code>StringBuffer</code>.
 177:    *
 178:    * @return the length of this <code>StringBuffer</code>
 179:    * @see #capacity()
 180:    * @see #setLength(int)
 181:    */
 182:   public synchronized int length()
 183:   {
 184:     return count;
 185:   }
 186: 
 187:   /**
 188:    * Get the total number of characters this <code>StringBuffer</code> can
 189:    * support before it must be grown.  Not to be confused with <em>length</em>.
 190:    *
 191:    * @return the capacity of this <code>StringBuffer</code>
 192:    * @see #length()
 193:    * @see #ensureCapacity(int)
 194:    */
 195:   public synchronized int capacity()
 196:   {
 197:     return value.length;
 198:   }
 199: 
 200:   /**
 201:    * Increase the capacity of this <code>StringBuffer</code>. This will
 202:    * ensure that an expensive growing operation will not occur until
 203:    * <code>minimumCapacity</code> is reached. The buffer is grown to the
 204:    * larger of <code>minimumCapacity</code> and
 205:    * <code>capacity() * 2 + 2</code>, if it is not already large enough.
 206:    *
 207:    * @param minimumCapacity the new capacity
 208:    * @see #capacity()
 209:    */
 210:   public synchronized void ensureCapacity(int minimumCapacity)
 211:   {
 212:     ensureCapacity_unsynchronized(minimumCapacity);
 213:   }
 214: 
 215:   /**
 216:    * Set the length of this StringBuffer. If the new length is greater than
 217:    * the current length, all the new characters are set to '\0'. If the new
 218:    * length is less than the current length, the first <code>newLength</code>
 219:    * characters of the old array will be preserved, and the remaining
 220:    * characters are truncated.
 221:    *
 222:    * @param newLength the new length
 223:    * @throws IndexOutOfBoundsException if the new length is negative
 224:    *         (while unspecified, this is a StringIndexOutOfBoundsException)
 225:    * @see #length()
 226:    */
 227:   public synchronized void setLength(int newLength)
 228:   {
 229:     if (newLength < 0)
 230:       throw new StringIndexOutOfBoundsException(newLength);
 231: 
 232:     int valueLength = value.length;
 233: 
 234:     /* Always call ensureCapacity_unsynchronized in order to preserve
 235:        copy-on-write semantics.  */
 236:     ensureCapacity_unsynchronized(newLength);
 237: 
 238:     if (newLength < valueLength)
 239:       {
 240:         /* If the StringBuffer's value just grew, then we know that
 241:            value is newly allocated and the region between count and
 242:            newLength is filled with '\0'.  */
 243:     count = newLength;
 244:       }
 245:     else
 246:       {
 247:     /* The StringBuffer's value doesn't need to grow.  However,
 248:        we should clear out any cruft that may exist.  */
 249:     while (count < newLength)
 250:           value[count++] = '\0';
 251:       }
 252:   }
 253: 
 254:   /**
 255:    * Get the character at the specified index.
 256:    *
 257:    * @param index the index of the character to get, starting at 0
 258:    * @return the character at the specified index
 259:    * @throws IndexOutOfBoundsException if index is negative or &gt;= length()
 260:    */
 261:   public synchronized char charAt(int index)
 262:   {
 263:     if (index < 0 || index >= count)
 264:       throw new StringIndexOutOfBoundsException(index);
 265:     return value[index];
 266:   }
 267: 
 268:   /**
 269:    * Get the code point at the specified index.  This is like #charAt(int),
 270:    * but if the character is the start of a surrogate pair, and the
 271:    * following character completes the pair, then the corresponding
 272:    * supplementary code point is returned.
 273:    * @param index the index of the codepoint to get, starting at 0
 274:    * @return the codepoint at the specified index
 275:    * @throws IndexOutOfBoundsException if index is negative or &gt;= length()
 276:    * @since 1.5
 277:    */
 278:   public synchronized int codePointAt(int index)
 279:   {
 280:     return Character.codePointAt(value, index, count);
 281:   }
 282: 
 283:   /**
 284:    * Get the code point before the specified index.  This is like
 285:    * #codePointAt(int), but checks the characters at <code>index-1</code> and
 286:    * <code>index-2</code> to see if they form a supplementary code point.
 287:    * @param index the index just past the codepoint to get, starting at 0
 288:    * @return the codepoint at the specified index
 289:    * @throws IndexOutOfBoundsException if index is negative or &gt;= length()
 290:    * @since 1.5
 291:    */
 292:   public synchronized int codePointBefore(int index)
 293:   {
 294:     // Character.codePointBefore() doesn't perform this check.  We
 295:     // could use the CharSequence overload, but this is just as easy.
 296:     if (index >= count)
 297:       throw new IndexOutOfBoundsException();
 298:     return Character.codePointBefore(value, index, 1);
 299:   }
 300: 
 301:   /**
 302:    * Get the specified array of characters. <code>srcOffset - srcEnd</code>
 303:    * characters will be copied into the array you pass in.
 304:    *
 305:    * @param srcOffset the index to start copying from (inclusive)
 306:    * @param srcEnd the index to stop copying from (exclusive)
 307:    * @param dst the array to copy into
 308:    * @param dstOffset the index to start copying into
 309:    * @throws NullPointerException if dst is null
 310:    * @throws IndexOutOfBoundsException if any source or target indices are
 311:    *         out of range (while unspecified, source problems cause a
 312:    *         StringIndexOutOfBoundsException, and dest problems cause an
 313:    *         ArrayIndexOutOfBoundsException)
 314:    * @see System#arraycopy(Object, int, Object, int, int)
 315:    */
 316:   public synchronized void getChars(int srcOffset, int srcEnd,
 317:                                     char[] dst, int dstOffset)
 318:   {
 319:     if (srcOffset < 0 || srcEnd > count || srcEnd < srcOffset)
 320:       throw new StringIndexOutOfBoundsException();
 321:     VMSystem.arraycopy(value, srcOffset, dst, dstOffset, srcEnd - srcOffset);
 322:   }
 323: 
 324:   /**
 325:    * Set the character at the specified index.
 326:    *
 327:    * @param index the index of the character to set starting at 0
 328:    * @param ch the value to set that character to
 329:    * @throws IndexOutOfBoundsException if index is negative or &gt;= length()
 330:    *         (while unspecified, this is a StringIndexOutOfBoundsException)
 331:    */
 332:   public synchronized void setCharAt(int index, char ch)
 333:   {
 334:     if (index < 0 || index >= count)
 335:       throw new StringIndexOutOfBoundsException(index);
 336:     // Call ensureCapacity to enforce copy-on-write.
 337:     ensureCapacity_unsynchronized(count);
 338:     value[index] = ch;
 339:   }
 340: 
 341:   /**
 342:    * Append the <code>String</code> value of the argument to this
 343:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 344:    * to <code>String</code>.
 345:    *
 346:    * @param obj the <code>Object</code> to convert and append
 347:    * @return this <code>StringBuffer</code>
 348:    * @see String#valueOf(Object)
 349:    * @see #append(String)
 350:    */
 351:   public StringBuffer append(Object obj)
 352:   {
 353:     return append(obj == null ? "null" : obj.toString());
 354:   }
 355: 
 356:   /**
 357:    * Append the <code>String</code> to this <code>StringBuffer</code>. If
 358:    * str is null, the String "null" is appended.
 359:    *
 360:    * @param str the <code>String</code> to append
 361:    * @return this <code>StringBuffer</code>
 362:    */
 363:   public synchronized StringBuffer append(String str)
 364:   {
 365:     if (str == null)
 366:       str = "null";
 367:     int len = str.count;
 368:     ensureCapacity_unsynchronized(count + len);
 369:     str.getChars(0, len, value, count);
 370:     count += len;
 371:     return this;
 372:   }
 373: 
 374:   /**
 375:    * Append the <code>StringBuffer</code> value of the argument to this
 376:    * <code>StringBuffer</code>. This behaves the same as
 377:    * <code>append((Object) stringBuffer)</code>, except it is more efficient.
 378:    *
 379:    * @param stringBuffer the <code>StringBuffer</code> to convert and append
 380:    * @return this <code>StringBuffer</code>
 381:    * @see #append(Object)
 382:    * @since 1.4
 383:    */
 384:   public synchronized StringBuffer append(StringBuffer stringBuffer)
 385:   {
 386:     if (stringBuffer == null)
 387:       return append("null");
 388:     synchronized (stringBuffer)
 389:       {
 390:         int len = stringBuffer.count;
 391:         ensureCapacity_unsynchronized(count + len);
 392:         VMSystem.arraycopy(stringBuffer.value, 0, value, count, len);
 393:         count += len;
 394:       }
 395:     return this;
 396:   }
 397: 
 398:   /**
 399:    * Append the <code>char</code> array to this <code>StringBuffer</code>.
 400:    * This is similar (but more efficient) than
 401:    * <code>append(new String(data))</code>, except in the case of null.
 402:    *
 403:    * @param data the <code>char[]</code> to append
 404:    * @return this <code>StringBuffer</code>
 405:    * @throws NullPointerException if <code>str</code> is <code>null</code>
 406:    * @see #append(char[], int, int)
 407:    */
 408:   public StringBuffer append(char[] data)
 409:   {
 410:     return append(data, 0, data.length);
 411:   }
 412: 
 413:   /**
 414:    * Append part of the <code>char</code> array to this
 415:    * <code>StringBuffer</code>. This is similar (but more efficient) than
 416:    * <code>append(new String(data, offset, count))</code>, except in the case
 417:    * of null.
 418:    *
 419:    * @param data the <code>char[]</code> to append
 420:    * @param offset the start location in <code>str</code>
 421:    * @param count the number of characters to get from <code>str</code>
 422:    * @return this <code>StringBuffer</code>
 423:    * @throws NullPointerException if <code>str</code> is <code>null</code>
 424:    * @throws IndexOutOfBoundsException if offset or count is out of range
 425:    *         (while unspecified, this is a StringIndexOutOfBoundsException)
 426:    */
 427:   public synchronized StringBuffer append(char[] data, int offset, int count)
 428:   {
 429:     if (offset < 0 || count < 0 || offset > data.length - count)
 430:       throw new StringIndexOutOfBoundsException();
 431:     ensureCapacity_unsynchronized(this.count + count);
 432:     VMSystem.arraycopy(data, offset, value, this.count, count);
 433:     this.count += count;
 434:     return this;
 435:   }
 436: 
 437:   /**
 438:    * Append the code point to this <code>StringBuffer</code>.
 439:    * This is like #append(char), but will append two characters
 440:    * if a supplementary code point is given.
 441:    *
 442:    * @param code the code point to append
 443:    * @return this <code>StringBuffer</code>
 444:    * @see Character#toChars(int, char[], int)
 445:    * @since 1.5
 446:    */
 447:   public synchronized StringBuffer appendCodePoint(int code)
 448:   {
 449:     int len = Character.charCount(code);
 450:     ensureCapacity_unsynchronized(count + len);
 451:     Character.toChars(code, value, count);
 452:     count += len;
 453:     return this;
 454:   }
 455: 
 456:   /**
 457:    * Append the <code>String</code> value of the argument to this
 458:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 459:    * to <code>String</code>.
 460:    *
 461:    * @param bool the <code>boolean</code> to convert and append
 462:    * @return this <code>StringBuffer</code>
 463:    * @see String#valueOf(boolean)
 464:    */
 465:   public StringBuffer append(boolean bool)
 466:   {
 467:     return append(bool ? "true" : "false");
 468:   }
 469: 
 470:   /**
 471:    * Append the <code>char</code> to this <code>StringBuffer</code>.
 472:    *
 473:    * @param ch the <code>char</code> to append
 474:    * @return this <code>StringBuffer</code>
 475:    */
 476:   public synchronized StringBuffer append(char ch)
 477:   {
 478:     ensureCapacity_unsynchronized(count + 1);
 479:     value[count++] = ch;
 480:     return this;
 481:   }
 482: 
 483:   /**
 484:    * Append the characters in the <code>CharSequence</code> to this
 485:    * buffer.
 486:    *
 487:    * @param seq the <code>CharSequence</code> providing the characters
 488:    * @return this <code>StringBuffer</code>
 489:    * @since 1.5
 490:    */
 491:   public synchronized StringBuffer append(CharSequence seq)
 492:   {
 493:     return append(seq, 0, seq.length());
 494:   }
 495: 
 496:   /**
 497:    * Append some characters from the <code>CharSequence</code> to this
 498:    * buffer.  If the argument is null, the four characters "null" are
 499:    * appended.
 500:    *
 501:    * @param seq the <code>CharSequence</code> providing the characters
 502:    * @param start the starting index
 503:    * @param end one past the final index
 504:    * @return this <code>StringBuffer</code>
 505:    * @since 1.5
 506:    */
 507:   public synchronized StringBuffer append(CharSequence seq, int start, int end)
 508:   {
 509:     if (seq == null)
 510:       return append("null");
 511:     if (end - start > 0)
 512:       {
 513:     ensureCapacity_unsynchronized(count + end - start);
 514:     for (; start < end; ++start)
 515:       value[count++] = seq.charAt(start);
 516:       }
 517:     return this;
 518:   }
 519: 
 520:   /**
 521:    * Append the <code>String</code> value of the argument to this
 522:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 523:    * to <code>String</code>.
 524:    *
 525:    * @param inum the <code>int</code> to convert and append
 526:    * @return this <code>StringBuffer</code>
 527:    * @see String#valueOf(int)
 528:    */
 529:   // This is native in libgcj, for efficiency.
 530:   public StringBuffer append(int inum)
 531:   {
 532:     return append(String.valueOf(inum));
 533:   }
 534: 
 535:   /**
 536:    * Append the <code>String</code> value of the argument to this
 537:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 538:    * to <code>String</code>.
 539:    *
 540:    * @param lnum the <code>long</code> to convert and append
 541:    * @return this <code>StringBuffer</code>
 542:    * @see String#valueOf(long)
 543:    */
 544:   public StringBuffer append(long lnum)
 545:   {
 546:     return append(Long.toString(lnum, 10));
 547:   }
 548: 
 549:   /**
 550:    * Append the <code>String</code> value of the argument to this
 551:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 552:    * to <code>String</code>.
 553:    *
 554:    * @param fnum the <code>float</code> to convert and append
 555:    * @return this <code>StringBuffer</code>
 556:    * @see String#valueOf(float)
 557:    */
 558:   public StringBuffer append(float fnum)
 559:   {
 560:     return append(Float.toString(fnum));
 561:   }
 562: 
 563:   /**
 564:    * Append the <code>String</code> value of the argument to this
 565:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 566:    * to <code>String</code>.
 567:    *
 568:    * @param dnum the <code>double</code> to convert and append
 569:    * @return this <code>StringBuffer</code>
 570:    * @see String#valueOf(double)
 571:    */
 572:   public StringBuffer append(double dnum)
 573:   {
 574:     return append(Double.toString(dnum));
 575:   }
 576: 
 577:   /**
 578:    * Delete characters from this <code>StringBuffer</code>.
 579:    * <code>delete(10, 12)</code> will delete 10 and 11, but not 12. It is
 580:    * harmless for end to be larger than length().
 581:    *
 582:    * @param start the first character to delete
 583:    * @param end the index after the last character to delete
 584:    * @return this <code>StringBuffer</code>
 585:    * @throws StringIndexOutOfBoundsException if start or end are out of bounds
 586:    * @since 1.2
 587:    */
 588:   public synchronized StringBuffer delete(int start, int end)
 589:   {
 590:     if (start < 0 || start > count || start > end)
 591:       throw new StringIndexOutOfBoundsException(start);
 592:     if (end > count)
 593:       end = count;
 594:     // This will unshare if required.
 595:     ensureCapacity_unsynchronized(count);
 596:     if (count - end != 0)
 597:       VMSystem.arraycopy(value, end, value, start, count - end);
 598:     count -= end - start;
 599:     return this;
 600:   }
 601: 
 602:   /**
 603:    * Delete a character from this <code>StringBuffer</code>.
 604:    *
 605:    * @param index the index of the character to delete
 606:    * @return this <code>StringBuffer</code>
 607:    * @throws StringIndexOutOfBoundsException if index is out of bounds
 608:    * @since 1.2
 609:    */
 610:   public StringBuffer deleteCharAt(int index)
 611:   {
 612:     return delete(index, index + 1);
 613:   }
 614: 
 615:   /**
 616:    * Replace characters between index <code>start</code> (inclusive) and
 617:    * <code>end</code> (exclusive) with <code>str</code>. If <code>end</code>
 618:    * is larger than the size of this StringBuffer, all characters after
 619:    * <code>start</code> are replaced.
 620:    *
 621:    * @param start the beginning index of characters to delete (inclusive)
 622:    * @param end the ending index of characters to delete (exclusive)
 623:    * @param str the new <code>String</code> to insert
 624:    * @return this <code>StringBuffer</code>
 625:    * @throws StringIndexOutOfBoundsException if start or end are out of bounds
 626:    * @throws NullPointerException if str is null
 627:    * @since 1.2
 628:    */
 629:   public synchronized StringBuffer replace(int start, int end, String str)
 630:   {
 631:     if (start < 0 || start > count || start > end)
 632:       throw new StringIndexOutOfBoundsException(start);
 633: 
 634:     int len = str.count;
 635:     // Calculate the difference in 'count' after the replace.
 636:     int delta = len - (end > count ? count : end) + start;
 637:     ensureCapacity_unsynchronized(count + delta);
 638: 
 639:     if (delta != 0 && end < count)
 640:       VMSystem.arraycopy(value, end, value, end + delta, count - end);
 641: 
 642:     str.getChars(0, len, value, start);
 643:     count += delta;
 644:     return this;
 645:   }
 646: 
 647:   /**
 648:    * Creates a substring of this StringBuffer, starting at a specified index
 649:    * and ending at the end of this StringBuffer.
 650:    *
 651:    * @param beginIndex index to start substring (base 0)
 652:    * @return new String which is a substring of this StringBuffer
 653:    * @throws StringIndexOutOfBoundsException if beginIndex is out of bounds
 654:    * @see #substring(int, int)
 655:    * @since 1.2
 656:    */
 657:   public String substring(int beginIndex)
 658:   {
 659:     return substring(beginIndex, count);
 660:   }
 661: 
 662:   /**
 663:    * Creates a substring of this StringBuffer, starting at a specified index
 664:    * and ending at one character before a specified index. This is implemented
 665:    * the same as <code>substring(beginIndex, endIndex)</code>, to satisfy
 666:    * the CharSequence interface.
 667:    *
 668:    * @param beginIndex index to start at (inclusive, base 0)
 669:    * @param endIndex index to end at (exclusive)
 670:    * @return new String which is a substring of this StringBuffer
 671:    * @throws IndexOutOfBoundsException if beginIndex or endIndex is out of
 672:    *         bounds
 673:    * @see #substring(int, int)
 674:    * @since 1.4
 675:    */
 676:   public CharSequence subSequence(int beginIndex, int endIndex)
 677:   {
 678:     return substring(beginIndex, endIndex);
 679:   }
 680: 
 681:   /**
 682:    * Creates a substring of this StringBuffer, starting at a specified index
 683:    * and ending at one character before a specified index.
 684:    *
 685:    * @param beginIndex index to start at (inclusive, base 0)
 686:    * @param endIndex index to end at (exclusive)
 687:    * @return new String which is a substring of this StringBuffer
 688:    * @throws StringIndexOutOfBoundsException if beginIndex or endIndex is out
 689:    *         of bounds
 690:    * @since 1.2
 691:    */
 692:   public synchronized String substring(int beginIndex, int endIndex)
 693:   {
 694:     int len = endIndex - beginIndex;
 695:     if (beginIndex < 0 || endIndex > count || endIndex < beginIndex)
 696:       throw new StringIndexOutOfBoundsException();
 697:     if (len == 0)
 698:       return "";
 699:     // Don't copy unless substring is smaller than 1/4 of the buffer.
 700:     boolean share_buffer = ((len << 2) >= value.length);
 701:     if (share_buffer)
 702:       this.shared = true;
 703:     // Package constructor avoids an array copy.
 704:     return new String(value, beginIndex, len, share_buffer);
 705:   }
 706: 
 707:   /**
 708:    * Insert a subarray of the <code>char[]</code> argument into this
 709:    * <code>StringBuffer</code>.
 710:    *
 711:    * @param offset the place to insert in this buffer
 712:    * @param str the <code>char[]</code> to insert
 713:    * @param str_offset the index in <code>str</code> to start inserting from
 714:    * @param len the number of characters to insert
 715:    * @return this <code>StringBuffer</code>
 716:    * @throws NullPointerException if <code>str</code> is <code>null</code>
 717:    * @throws StringIndexOutOfBoundsException if any index is out of bounds
 718:    * @since 1.2
 719:    */
 720:   public synchronized StringBuffer insert(int offset,
 721:                                           char[] str, int str_offset, int len)
 722:   {
 723:     if (offset < 0 || offset > count || len < 0
 724:         || str_offset < 0 || str_offset > str.length - len)
 725:       throw new StringIndexOutOfBoundsException();
 726:     ensureCapacity_unsynchronized(count + len);
 727:     VMSystem.arraycopy(value, offset, value, offset + len, count - offset);
 728:     VMSystem.arraycopy(str, str_offset, value, offset, len);
 729:     count += len;
 730:     return this;
 731:   }
 732: 
 733:   /**
 734:    * Insert the <code>String</code> value of the argument into this
 735:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 736:    * to <code>String</code>.
 737:    *
 738:    * @param offset the place to insert in this buffer
 739:    * @param obj the <code>Object</code> to convert and insert
 740:    * @return this <code>StringBuffer</code>
 741:    * @exception StringIndexOutOfBoundsException if offset is out of bounds
 742:    * @see String#valueOf(Object)
 743:    */
 744:   public StringBuffer insert(int offset, Object obj)
 745:   {
 746:     return insert(offset, obj == null ? "null" : obj.toString());
 747:   }
 748: 
 749:   /**
 750:    * Insert the <code>String</code> argument into this
 751:    * <code>StringBuffer</code>. If str is null, the String "null" is used
 752:    * instead.
 753:    *
 754:    * @param offset the place to insert in this buffer
 755:    * @param str the <code>String</code> to insert
 756:    * @return this <code>StringBuffer</code>
 757:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 758:    */
 759:   public synchronized StringBuffer insert(int offset, String str)
 760:   {
 761:     if (offset < 0 || offset > count)
 762:       throw new StringIndexOutOfBoundsException(offset);
 763:     if (str == null)
 764:       str = "null";
 765:     int len = str.count;
 766:     ensureCapacity_unsynchronized(count + len);
 767:     VMSystem.arraycopy(value, offset, value, offset + len, count - offset);
 768:     str.getChars(0, len, value, offset);
 769:     count += len;
 770:     return this;
 771:   }
 772: 
 773:   /**
 774:    * Insert the <code>CharSequence</code> argument into this
 775:    * <code>StringBuffer</code>.  If the sequence is null, the String
 776:    * "null" is used instead.
 777:    *
 778:    * @param offset the place to insert in this buffer
 779:    * @param sequence the <code>CharSequence</code> to insert
 780:    * @return this <code>StringBuffer</code>
 781:    * @throws IndexOutOfBoundsException if offset is out of bounds
 782:    * @since 1.5
 783:    */
 784:   public synchronized StringBuffer insert(int offset, CharSequence sequence)
 785:   {
 786:     if (sequence == null)
 787:       sequence = "null";
 788:     return insert(offset, sequence, 0, sequence.length());
 789:   }
 790: 
 791:   /**
 792:    * Insert a subsequence of the <code>CharSequence</code> argument into this
 793:    * <code>StringBuffer</code>.  If the sequence is null, the String
 794:    * "null" is used instead.
 795:    *
 796:    * @param offset the place to insert in this buffer
 797:    * @param sequence the <code>CharSequence</code> to insert
 798:    * @param start the starting index of the subsequence
 799:    * @param end one past the ending index of the subsequence
 800:    * @return this <code>StringBuffer</code>
 801:    * @throws IndexOutOfBoundsException if offset, start,
 802:    * or end are out of bounds
 803:    * @since 1.5
 804:    */
 805:   public synchronized StringBuffer insert(int offset, CharSequence sequence,
 806:                       int start, int end)
 807:   {
 808:     if (sequence == null)
 809:       sequence = "null";
 810:     if (start < 0 || end < 0 || start > end || end > sequence.length())
 811:       throw new IndexOutOfBoundsException();
 812:     int len = end - start;
 813:     ensureCapacity_unsynchronized(count + len);
 814:     VMSystem.arraycopy(value, offset, value, offset + len, count - offset);
 815:     for (int i = start; i < end; ++i)
 816:       value[offset++] = sequence.charAt(i);
 817:     count += len;
 818:     return this;
 819:   }
 820: 
 821:   /**
 822:    * Insert the <code>char[]</code> argument into this
 823:    * <code>StringBuffer</code>.
 824:    *
 825:    * @param offset the place to insert in this buffer
 826:    * @param data the <code>char[]</code> to insert
 827:    * @return this <code>StringBuffer</code>
 828:    * @throws NullPointerException if <code>data</code> is <code>null</code>
 829:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 830:    * @see #insert(int, char[], int, int)
 831:    */
 832:   public StringBuffer insert(int offset, char[] data)
 833:   {
 834:     return insert(offset, data, 0, data.length);
 835:   }
 836: 
 837:   /**
 838:    * Insert the <code>String</code> value of the argument into this
 839:    * <code>StringBuffer</code>. Uses <code>String.valueOf()</code> to convert
 840:    * to <code>String</code>.
 841:    *
 842:    * @param offset the place to insert in this buffer
 843:    * @param bool the <code>boolean</code> to convert and insert
 844:    * @return this <code>StringBuffer</code>
 845:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 846:    * @see String#valueOf(boolean)
 847:    */
 848:   public