Source for java.lang.StringBuilder

   1: /* StringBuilder.java -- Unsynchronized 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>StringBuilder</code> represents a changeable <code>String</code>.
  45:  * It provides the operations required to modify the
  46:  * <code>StringBuilder</code>, including insert, replace, delete, append,
  47:  * and reverse. It like <code>StringBuffer</code>, but is not
  48:  * synchronized.  It is ideal for use when it is known that the
  49:  * object will only be used from a single thread.
  50:  *
  51:  * <p><code>StringBuilder</code>s are variable-length in nature, so even if
  52:  * you initialize them to a certain size, they can still grow larger than
  53:  * that. <em>Capacity</em> indicates the number of characters the
  54:  * <code>StringBuilder</code> can have in it before it has to grow (growing
  55:  * the char array is an expensive operation involving <code>new</code>).
  56:  *
  57:  * <p>Incidentally, compilers often implement the String operator "+"
  58:  * by using a <code>StringBuilder</code> operation:<br>
  59:  * <code>a + b</code><br>
  60:  * is the same as<br>
  61:  * <code>new StringBuilder().append(a).append(b).toString()</code>.
  62:  *
  63:  * <p>Classpath's StringBuilder is capable of sharing memory with Strings for
  64:  * efficiency.  This will help when a StringBuilder is converted to a String
  65:  * and the StringBuilder is not changed after that (quite common when
  66:  * performing string concatenation).
  67:  *
  68:  * @author Paul Fisher
  69:  * @author John Keiser
  70:  * @author Tom Tromey
  71:  * @author Eric Blake (ebb9@email.byu.edu)
  72:  * @see String
  73:  * @see StringBuffer
  74:  *
  75:  * @since 1.5
  76:  */
  77: // FIX15: Implement Appendable when co-variant methods are available
  78: public final class StringBuilder
  79:   implements Serializable, CharSequence
  80: {
  81:   // Implementation note: if you change this class, you usually will
  82:   // want to change StringBuffer as well.
  83: 
  84:   /**
  85:    * For compatability with Sun's JDK
  86:    */
  87:   private static final long serialVersionUID = 4383685877147921099L;
  88: 
  89:   /**
  90:    * Index of next available character (and thus the size of the current
  91:    * string contents).  Note that this has permissions set this way so that
  92:    * String can get the value.
  93:    *
  94:    * @serial the number of characters in the buffer
  95:    */
  96:   int count;
  97: 
  98:   /**
  99:    * The buffer.  Note that this has permissions set this way so that String
 100:    * can get the value.
 101:    *
 102:    * @serial the buffer
 103:    */
 104:   char[] value;
 105: 
 106:   /**
 107:    * The default capacity of a buffer.
 108:    */
 109:   private static final int DEFAULT_CAPACITY = 16;
 110: 
 111:   /**
 112:    * Create a new StringBuilder with default capacity 16.
 113:    */
 114:   public StringBuilder()
 115:   {
 116:     this(DEFAULT_CAPACITY);
 117:   }
 118: 
 119:   /**
 120:    * Create an empty <code>StringBuilder</code> with the specified initial
 121:    * capacity.
 122:    *
 123:    * @param capacity the initial capacity
 124:    * @throws NegativeArraySizeException if capacity is negative
 125:    */
 126:   public StringBuilder(int capacity)
 127:   {
 128:     value = new char[capacity];
 129:   }
 130: 
 131:   /**
 132:    * Create a new <code>StringBuilder</code> with the characters in the
 133:    * specified <code>String</code>. Initial capacity will be the size of the
 134:    * String plus 16.
 135:    *
 136:    * @param str the <code>String</code> to convert
 137:    * @throws NullPointerException if str is null
 138:    */
 139:   public StringBuilder(String str)
 140:   {
 141:     // Unfortunately, because the size is 16 larger, we cannot share.
 142:     count = str.count;
 143:     value = new char[count + DEFAULT_CAPACITY];
 144:     str.getChars(0, count, value, 0);
 145:   }
 146: 
 147:   /**
 148:    * Create a new <code>StringBuilder</code> with the characters in the
 149:    * specified <code>CharSequence</code>. Initial capacity will be the
 150:    * length of the sequence plus 16; if the sequence reports a length
 151:    * less than or equal to 0, then the initial capacity will be 16.
 152:    *
 153:    * @param seq the initializing <code>CharSequence</code>
 154:    * @throws NullPointerException if str is null
 155:    */
 156:   public StringBuilder(CharSequence seq)
 157:   {
 158:     int len = seq.length();
 159:     count = len <= 0 ? 0 : len;
 160:     value = new char[count + DEFAULT_CAPACITY];
 161:     for (int i = 0; i < len; ++i)
 162:       value[i] = seq.charAt(i);
 163:   }
 164: 
 165:   /**
 166:    * Get the length of the <code>String</code> this <code>StringBuilder</code>
 167:    * would create. Not to be confused with the <em>capacity</em> of the
 168:    * <code>StringBuilder</code>.
 169:    *
 170:    * @return the length of this <code>StringBuilder</code>
 171:    * @see #capacity()
 172:    * @see #setLength(int)
 173:    */
 174:   public int length()
 175:   {
 176:     return count;
 177:   }
 178: 
 179:   /**
 180:    * Get the total number of characters this <code>StringBuilder</code> can
 181:    * support before it must be grown.  Not to be confused with <em>length</em>.
 182:    *
 183:    * @return the capacity of this <code>StringBuilder</code>
 184:    * @see #length()
 185:    * @see #ensureCapacity(int)
 186:    */
 187:   public int capacity()
 188:   {
 189:     return value.length;
 190:   }
 191: 
 192:   /**
 193:    * Increase the capacity of this <code>StringBuilder</code>. This will
 194:    * ensure that an expensive growing operation will not occur until
 195:    * <code>minimumCapacity</code> is reached. The buffer is grown to the
 196:    * larger of <code>minimumCapacity</code> and
 197:    * <code>capacity() * 2 + 2</code>, if it is not already large enough.
 198:    *
 199:    * @param minimumCapacity the new capacity
 200:    * @see #capacity()
 201:    */
 202:   public void ensureCapacity(int minimumCapacity)
 203:   {
 204:     if (minimumCapacity > value.length)
 205:       {
 206:         int max = value.length * 2 + 2;
 207:         minimumCapacity = (minimumCapacity < max ? max : minimumCapacity);
 208:         char[] nb = new char[minimumCapacity];
 209:         System.arraycopy(value, 0, nb, 0, count);
 210:         value = nb;
 211:       }
 212:   }
 213: 
 214:   /**
 215:    * Set the length of this StringBuilder. If the new length is greater than
 216:    * the current length, all the new characters are set to '\0'. If the new
 217:    * length is less than the current length, the first <code>newLength</code>
 218:    * characters of the old array will be preserved, and the remaining
 219:    * characters are truncated.
 220:    *
 221:    * @param newLength the new length
 222:    * @throws IndexOutOfBoundsException if the new length is negative
 223:    *         (while unspecified, this is a StringIndexOutOfBoundsException)
 224:    * @see #length()
 225:    */
 226:   public void setLength(int newLength)
 227:   {
 228:     if (newLength < 0)
 229:       throw new StringIndexOutOfBoundsException(newLength);
 230: 
 231:     int valueLength = value.length;
 232: 
 233:     /* Always call ensureCapacity in order to preserve copy-on-write
 234:        semantics.  */
 235:     ensureCapacity(newLength);
 236: 
 237:     if (newLength < valueLength)
 238:       {
 239:         /* If the StringBuilder's value just grew, then we know that
 240:            value is newly allocated and the region between count and
 241:            newLength is filled with '\0'.  */
 242:     count = newLength;
 243:       }
 244:     else
 245:       {
 246:     /* The StringBuilder's value doesn't need to grow.  However,
 247:        we should clear out any cruft that may exist.  */
 248:     while (count < newLength)
 249:           value[count++] = '\0';
 250:       }
 251:   }
 252: 
 253:   /**
 254:    * Get the character at the specified index.
 255:    *
 256:    * @param index the index of the character to get, starting at 0
 257:    * @return the character at the specified index
 258:    * @throws IndexOutOfBoundsException if index is negative or &gt;= length()
 259:    *         (while unspecified, this is a StringIndexOutOfBoundsException)
 260:    */
 261:   public 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 specified array of characters. <code>srcOffset - srcEnd</code>
 270:    * characters will be copied into the array you pass in.
 271:    *
 272:    * @param srcOffset the index to start copying from (inclusive)
 273:    * @param srcEnd the index to stop copying from (exclusive)
 274:    * @param dst the array to copy into
 275:    * @param dstOffset the index to start copying into
 276:    * @throws NullPointerException if dst is null
 277:    * @throws IndexOutOfBoundsException if any source or target indices are
 278:    *         out of range (while unspecified, source problems cause a
 279:    *         StringIndexOutOfBoundsException, and dest problems cause an
 280:    *         ArrayIndexOutOfBoundsException)
 281:    * @see System#arraycopy(Object, int, Object, int, int)
 282:    */
 283:   public void getChars(int srcOffset, int srcEnd,
 284:                char[] dst, int dstOffset)
 285:   {
 286:     if (srcOffset < 0 || srcEnd > count || srcEnd < srcOffset)
 287:       throw new StringIndexOutOfBoundsException();
 288:     System.arraycopy(value, srcOffset, dst, dstOffset, srcEnd - srcOffset);
 289:   }
 290: 
 291:   /**
 292:    * Set the character at the specified index.
 293:    *
 294:    * @param index the index of the character to set starting at 0
 295:    * @param ch the value to set that character to
 296:    * @throws IndexOutOfBoundsException if index is negative or &gt;= length()
 297:    *         (while unspecified, this is a StringIndexOutOfBoundsException)
 298:    */
 299:   public void setCharAt(int index, char ch)
 300:   {
 301:     if (index < 0 || index >= count)
 302:       throw new StringIndexOutOfBoundsException(index);
 303:     // Call ensureCapacity to enforce copy-on-write.
 304:     ensureCapacity(count);
 305:     value[index] = ch;
 306:   }
 307: 
 308:   /**
 309:    * Append the <code>String</code> value of the argument to this
 310:    * <code>StringBuilder</code>. Uses <code>String.valueOf()</code> to convert
 311:    * to <code>String</code>.
 312:    *
 313:    * @param obj the <code>Object</code> to convert and append
 314:    * @return this <code>StringBuilder</code>
 315:    * @see String#valueOf(Object)
 316:    * @see #append(String)
 317:    */
 318:   public StringBuilder append(Object obj)
 319:   {
 320:     return append(obj == null ? "null" : obj.toString());
 321:   }
 322: 
 323:   /**
 324:    * Append the <code>String</code> to this <code>StringBuilder</code>. If
 325:    * str is null, the String "null" is appended.
 326:    *
 327:    * @param str the <code>String</code> to append
 328:    * @return this <code>StringBuilder</code>
 329:    */
 330:   public StringBuilder append(String str)
 331:   {
 332:     if (str == null)
 333:       str = "null";
 334:     int len = str.count;
 335:     ensureCapacity(count + len);
 336:     str.getChars(0, len, value, count);
 337:     count += len;
 338:     return this;
 339:   }
 340: 
 341:   /**
 342:    * Append the <code>StringBuilder</code> value of the argument to this
 343:    * <code>StringBuilder</code>. This behaves the same as
 344:    * <code>append((Object) stringBuffer)</code>, except it is more efficient.
 345:    *
 346:    * @param stringBuffer the <code>StringBuilder</code> to convert and append
 347:    * @return this <code>StringBuilder</code>
 348:    * @see #append(Object)
 349:    */
 350:   public StringBuilder append(StringBuffer stringBuffer)
 351:   {
 352:     if (stringBuffer == null)
 353:       return append("null");
 354:     synchronized (stringBuffer)
 355:       {
 356:     int len = stringBuffer.count;
 357:     ensureCapacity(count + len);
 358:     System.arraycopy(stringBuffer.value, 0, value, count, len);
 359:     count += len;
 360:       }
 361:     return this;
 362:   }
 363: 
 364:   /**
 365:    * Append the <code>char</code> array to this <code>StringBuilder</code>.
 366:    * This is similar (but more efficient) than
 367:    * <code>append(new String(data))</code>, except in the case of null.
 368:    *
 369:    * @param data the <code>char[]</code> to append
 370:    * @return this <code>StringBuilder</code>
 371:    * @throws NullPointerException if <code>str</code> is <code>null</code>
 372:    * @see #append(char[], int, int)
 373:    */
 374:   public StringBuilder append(char[] data)
 375:   {
 376:     return append(data, 0, data.length);
 377:   }
 378: 
 379:   /**
 380:    * Append part of the <code>char</code> array to this
 381:    * <code>StringBuilder</code>. This is similar (but more efficient) than
 382:    * <code>append(new String(data, offset, count))</code>, except in the case
 383:    * of null.
 384:    *
 385:    * @param data the <code>char[]</code> to append
 386:    * @param offset the start location in <code>str</code>
 387:    * @param count the number of characters to get from <code>str</code>
 388:    * @return this <code>StringBuilder</code>
 389:    * @throws NullPointerException if <code>str</code> is <code>null</code>
 390:    * @throws IndexOutOfBoundsException if offset or count is out of range
 391:    *         (while unspecified, this is a StringIndexOutOfBoundsException)
 392:    */
 393:   public StringBuilder append(char[] data, int offset, int count)
 394:   {
 395:     if (offset < 0 || count < 0 || offset > data.length - count)
 396:       throw new StringIndexOutOfBoundsException();
 397:     ensureCapacity(this.count + count);
 398:     System.arraycopy(data, offset, value, this.count, count);
 399:     this.count += count;
 400:     return this;
 401:   }
 402: 
 403:   /**
 404:    * Append the <code>String</code> value of the argument to this
 405:    * <code>StringBuilder</code>. Uses <code>String.valueOf()</code> to convert
 406:    * to <code>String</code>.
 407:    *
 408:    * @param bool the <code>boolean</code> to convert and append
 409:    * @return this <code>StringBuilder</code>
 410:    * @see String#valueOf(boolean)
 411:    */
 412:   public StringBuilder append(boolean bool)
 413:   {
 414:     return append(bool ? "true" : "false");
 415:   }
 416: 
 417:   /**
 418:    * Append the <code>char</code> to this <code>StringBuilder</code>.
 419:    *
 420:    * @param ch the <code>char</code> to append
 421:    * @return this <code>StringBuilder</code>
 422:    */
 423:   public StringBuilder append(char ch)
 424:   {
 425:     ensureCapacity(count + 1);
 426:     value[count++] = ch;
 427:     return this;
 428:   }
 429: 
 430:   /**
 431:    * Append the characters in the <code>CharSequence</code> to this
 432:    * buffer.
 433:    *
 434:    * @param seq the <code>CharSequence</code> providing the characters
 435:    * @return this <code>StringBuilder</code>
 436:    */
 437:   public StringBuilder append(CharSequence seq)
 438:   {
 439:     return append(seq, 0, seq.length());
 440:   }
 441: 
 442:   /**
 443:    * Append some characters from the <code>CharSequence</code> to this
 444:    * buffer.  If the argument is null, the four characters "null" are
 445:    * appended.
 446:    *
 447:    * @param seq the <code>CharSequence</code> providing the characters
 448:    * @param start the starting index
 449:    * @param end one past the final index
 450:    * @return this <code>StringBuilder</code>
 451:    */
 452:   public StringBuilder append(CharSequence seq, int start,
 453:                   int end)
 454:   {
 455:     if (seq == null)
 456:       return append("null");
 457:     if (end - start > 0)
 458:       {
 459:     ensureCapacity(count + end - start);
 460:     for (; start < end; ++start)
 461:       value[count++] = seq.charAt(start);
 462:       }
 463:     return this;
 464:   }
 465: 
 466:   /**
 467:    * Append the <code>String</code> value of the argument to this
 468:    * <code>StringBuilder</code>. Uses <code>String.valueOf()</code> to convert
 469:    * to <code>String</code>.
 470:    *
 471:    * @param inum the <code>int</code> to convert and append
 472:    * @return this <code>StringBuilder</code>
 473:    * @see String#valueOf(int)
 474:    */
 475:   // This is native in libgcj, for efficiency.
 476:   public StringBuilder append(int inum)
 477:   {
 478:     return append(String.valueOf(inum));
 479:   }
 480: 
 481:   /**
 482:    * Append the <code>String</code> value of the argument to this
 483:    * <code>StringBuilder</code>. Uses <code>String.valueOf()</code> to convert
 484:    * to <code>String</code>.
 485:    *
 486:    * @param lnum the <code>long</code> to convert and append
 487:    * @return this <code>StringBuilder</code>
 488:    * @see String#valueOf(long)
 489:    */
 490:   public StringBuilder append(long lnum)
 491:   {
 492:     return append(Long.toString(lnum, 10));
 493:   }
 494: 
 495:   /**
 496:    * Append the <code>String</code> value of the argument to this
 497:    * <code>StringBuilder</code>. Uses <code>String.valueOf()</code> to convert
 498:    * to <code>String</code>.
 499:    *
 500:    * @param fnum the <code>float</code> to convert and append
 501:    * @return this <code>StringBuilder</code>
 502:    * @see String#valueOf(float)
 503:    */
 504:   public StringBuilder append(float fnum)
 505:   {
 506:     return append(Float.toString(fnum));
 507:   }
 508: 
 509:   /**
 510:    * Append the <code>String</code> value of the argument to this
 511:    * <code>StringBuilder</code>. Uses <code>String.valueOf()</code> to convert
 512:    * to <code>String</code>.
 513:    *
 514:    * @param dnum the <code>double</code> to convert and append
 515:    * @return this <code>StringBuilder</code>
 516:    * @see String#valueOf(double)
 517:    */
 518:   public StringBuilder append(double dnum)
 519:   {
 520:     return append(Double.toString(dnum));
 521:   }
 522: 
 523:   /**
 524:    * Delete characters from this <code>StringBuilder</code>.
 525:    * <code>delete(10, 12)</code> will delete 10 and 11, but not 12. It is
 526:    * harmless for end to be larger than length().
 527:    *
 528:    * @param start the first character to delete
 529:    * @param end the index after the last character to delete
 530:    * @return this <code>StringBuilder</code>
 531:    * @throws StringIndexOutOfBoundsException if start or end are out of bounds
 532:    */
 533:   public StringBuilder delete(int start, int end)
 534:   {
 535:     if (start < 0 || start > count || start > end)
 536:       throw new StringIndexOutOfBoundsException(start);
 537:     if (end > count)
 538:       end = count;
 539:     // This will unshare if required.
 540:     ensureCapacity(count);
 541:     if (count - end != 0)
 542:       System.arraycopy(value, end, value, start, count - end);
 543:     count -= end - start;
 544:     return this;
 545:   }
 546: 
 547:   /**
 548:    * Delete a character from this <code>StringBuilder</code>.
 549:    *
 550:    * @param index the index of the character to delete
 551:    * @return this <code>StringBuilder</code>
 552:    * @throws StringIndexOutOfBoundsException if index is out of bounds
 553:    */
 554:   public StringBuilder deleteCharAt(int index)
 555:   {
 556:     return delete(index, index + 1);
 557:   }
 558: 
 559:   /**
 560:    * Replace characters between index <code>start</code> (inclusive) and
 561:    * <code>end</code> (exclusive) with <code>str</code>. If <code>end</code>
 562:    * is larger than the size of this StringBuilder, all characters after
 563:    * <code>start</code> are replaced.
 564:    *
 565:    * @param start the beginning index of characters to delete (inclusive)
 566:    * @param end the ending index of characters to delete (exclusive)
 567:    * @param str the new <code>String</code> to insert
 568:    * @return this <code>StringBuilder</code>
 569:    * @throws StringIndexOutOfBoundsException if start or end are out of bounds
 570:    * @throws NullPointerException if str is null
 571:    */
 572:   public StringBuilder replace(int start, int end, String str)
 573:   {
 574:     if (start < 0 || start > count || start > end)
 575:       throw new StringIndexOutOfBoundsException(start);
 576: 
 577:     int len = str.count;
 578:     // Calculate the difference in 'count' after the replace.
 579:     int delta = len - (end > count ? count : end) + start;
 580:     ensureCapacity(count + delta);
 581: 
 582:     if (delta != 0 && end < count)
 583:       System.arraycopy(value, end, value, end + delta, count - end);
 584: 
 585:     str.getChars(0, len, value, start);
 586:     count += delta;
 587:     return this;
 588:   }
 589: 
 590:   /**
 591:    * Creates a substring of this StringBuilder, starting at a specified index
 592:    * and ending at the end of this StringBuilder.
 593:    *
 594:    * @param beginIndex index to start substring (base 0)
 595:    * @return new String which is a substring of this StringBuilder
 596:    * @throws StringIndexOutOfBoundsException if beginIndex is out of bounds
 597:    * @see #substring(int, int)
 598:    */
 599:   public String substring(int beginIndex)
 600:   {
 601:     return substring(beginIndex, count);
 602:   }
 603: 
 604:   /**
 605:    * Creates a substring of this StringBuilder, starting at a specified index
 606:    * and ending at one character before a specified index. This is implemented
 607:    * the same as <code>substring(beginIndex, endIndex)</code>, to satisfy
 608:    * the CharSequence interface.
 609:    *
 610:    * @param beginIndex index to start at (inclusive, base 0)
 611:    * @param endIndex index to end at (exclusive)
 612:    * @return new String which is a substring of this StringBuilder
 613:    * @throws IndexOutOfBoundsException if beginIndex or endIndex is out of
 614:    *         bounds
 615:    * @see #substring(int, int)
 616:    */
 617:   public CharSequence subSequence(int beginIndex, int endIndex)
 618:   {
 619:     return substring(beginIndex, endIndex);
 620:   }
 621: 
 622:   /**
 623:    * Creates a substring of this StringBuilder, starting at a specified index
 624:    * and ending at one character before a specified index.
 625:    *
 626:    * @param beginIndex index to start at (inclusive, base 0)
 627:    * @param endIndex index to end at (exclusive)
 628:    * @return new String which is a substring of this StringBuilder
 629:    * @throws StringIndexOutOfBoundsException if beginIndex or endIndex is out
 630:    *         of bounds
 631:    */
 632:   public String substring(int beginIndex, int endIndex)
 633:   {
 634:     int len = endIndex - beginIndex;
 635:     if (beginIndex < 0 || endIndex > count || endIndex < beginIndex)
 636:       throw new StringIndexOutOfBoundsException();
 637:     if (len == 0)
 638:       return "";
 639:     return new String(value, beginIndex, len);
 640:   }
 641: 
 642:   /**
 643:    * Insert a subarray of the <code>char[]</code> argument into this
 644:    * <code>StringBuilder</code>.
 645:    *
 646:    * @param offset the place to insert in this buffer
 647:    * @param str the <code>char[]</code> to insert
 648:    * @param str_offset the index in <code>str</code> to start inserting from
 649:    * @param len the number of characters to insert
 650:    * @return this <code>StringBuilder</code>
 651:    * @throws NullPointerException if <code>str</code> is <code>null</code>
 652:    * @throws StringIndexOutOfBoundsException if any index is out of bounds
 653:    */
 654:   public StringBuilder insert(int offset,
 655:                   char[] str, int str_offset, int len)
 656:   {
 657:     if (offset < 0 || offset > count || len < 0
 658:         || str_offset < 0 || str_offset > str.length - len)
 659:       throw new StringIndexOutOfBoundsException();
 660:     ensureCapacity(count + len);
 661:     System.arraycopy(value, offset, value, offset + len, count - offset);
 662:     System.arraycopy(str, str_offset, value, offset, len);
 663:     count += len;
 664:     return this;
 665:   }
 666: 
 667:   /**
 668:    * Insert the <code>String</code> value of the argument into this
 669:    * <code>StringBuilder</code>. Uses <code>String.valueOf()</code> to convert
 670:    * to <code>String</code>.
 671:    *
 672:    * @param offset the place to insert in this buffer
 673:    * @param obj the <code>Object</code> to convert and insert
 674:    * @return this <code>StringBuilder</code>
 675:    * @exception StringIndexOutOfBoundsException if offset is out of bounds
 676:    * @see String#valueOf(Object)
 677:    */
 678:   public StringBuilder insert(int offset, Object obj)
 679:   {
 680:     return insert(offset, obj == null ? "null" : obj.toString());
 681:   }
 682: 
 683:   /**
 684:    * Insert the <code>String</code> argument into this
 685:    * <code>StringBuilder</code>. If str is null, the String "null" is used
 686:    * instead.
 687:    *
 688:    * @param offset the place to insert in this buffer
 689:    * @param str the <code>String</code> to insert
 690:    * @return this <code>StringBuilder</code>
 691:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 692:    */
 693:   public StringBuilder insert(int offset, String str)
 694:   {
 695:     if (offset < 0 || offset > count)
 696:       throw new StringIndexOutOfBoundsException(offset);
 697:     if (str == null)
 698:       str = "null";
 699:     int len = str.count;
 700:     ensureCapacity(count + len);
 701:     System.arraycopy(value, offset, value, offset + len, count - offset);
 702:     str.getChars(0, len, value, offset);
 703:     count += len;
 704:     return this;
 705:   }
 706: 
 707:   /**
 708:    * Insert the <code>char[]</code> argument into this
 709:    * <code>StringBuilder</code>.
 710:    *
 711:    * @param offset the place to insert in this buffer
 712:    * @param data the <code>char[]</code> to insert
 713:    * @return this <code>StringBuilder</code>
 714:    * @throws NullPointerException if <code>data</code> is <code>null</code>
 715:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 716:    * @see #insert(int, char[], int, int)
 717:    */
 718:   public StringBuilder insert(int offset, char[] data)
 719:   {
 720:     return insert(offset, data, 0, data.length);
 721:   }
 722: 
 723:   /**
 724:    * Insert the <code>String</code> value of the argument into this
 725:    * <code>StringBuilder</code>. Uses <code>String.valueOf()</code> to convert
 726:    * to <code>String</code>.
 727:    *
 728:    * @param offset the place to insert in this buffer
 729:    * @param bool the <code>boolean</code> to convert and insert
 730:    * @return this <code>StringBuilder</code>
 731:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 732:    * @see String#valueOf(boolean)
 733:    */
 734:   public StringBuilder insert(int offset, boolean bool)
 735:   {
 736:     return insert(offset, bool ? "true" : "false");
 737:   }
 738: 
 739:   /**
 740:    * Insert the <code>char</code> argument into this <code>StringBuilder</code>.
 741:    *
 742:    * @param offset the place to insert in this buffer
 743:    * @param ch the <code>char</code> to insert
 744:    * @return this <code>StringBuilder</code>
 745:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 746:    */
 747:   public StringBuilder insert(int offset, char ch)
 748:   {
 749:     if (offset < 0 || offset > count)
 750:       throw new StringIndexOutOfBoundsException(offset);
 751:     ensureCapacity(count + 1);
 752:     System.arraycopy(value, offset, value, offset + 1, count - offset);
 753:     value[offset] = ch;
 754:     count++;
 755:     return this;
 756:   }
 757: 
 758:   /**
 759:    * Insert the <code>String</code> value of the argument into this
 760:    * <code>StringBuilder</code>. Uses <code>String.valueOf()</code> to convert
 761:    * to <code>String</code>.
 762:    *
 763:    * @param offset the place to insert in this buffer
 764:    * @param inum the <code>int</code> to convert and insert
 765:    * @return this <code>StringBuilder</code>
 766:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 767:    * @see String#valueOf(int)
 768:    */
 769:   public StringBuilder insert(int offset, int inum)
 770:   {
 771:     return insert(offset, String.valueOf(inum));
 772:   }
 773: 
 774:   /**
 775:    * Insert the <code>String</code> value of the argument into this
 776:    * <code>StringBuilder</code>. Uses <code>String.valueOf()</code> to convert
 777:    * to <code>String</code>.
 778:    *
 779:    * @param offset the place to insert in this buffer
 780:    * @param lnum the <code>long</code> to convert and insert
 781:    * @return this <code>StringBuilder</code>
 782:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 783:    * @see String#valueOf(long)
 784:    */
 785:   public StringBuilder insert(int offset, long lnum)
 786:   {
 787:     return insert(offset, Long.toString(lnum, 10));
 788:   }
 789: 
 790:   /**
 791:    * Insert the <code>String</code> value of the argument into this
 792:    * <code>StringBuilder</code>. Uses <code>String.valueOf()</code> to convert
 793:    * to <code>String</code>.
 794:    *
 795:    * @param offset the place to insert in this buffer
 796:    * @param fnum the <code>float</code> to convert and insert
 797:    * @return this <code>StringBuilder</code>
 798:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 799:    * @see String#valueOf(float)
 800:    */
 801:   public StringBuilder insert(int offset, float fnum)
 802:   {
 803:     return insert(offset, Float.toString(fnum));
 804:   }
 805: 
 806:   /**
 807:    * Insert the <code>String</code> value of the argument into this
 808:    * <code>StringBuilder</code>. Uses <code>String.valueOf()</code> to convert
 809:    * to <code>String</code>.
 810:    *
 811:    * @param offset the place to insert in this buffer
 812:    * @param dnum the <code>double</code> to convert and insert
 813:    * @return this <code>StringBuilder</code>
 814:    * @throws StringIndexOutOfBoundsException if offset is out of bounds
 815:    * @see String#valueOf(double)
 816:    */
 817:   public StringBuilder insert(int offset, double dnum)
 818:   {
 819:     return insert(offset, Double.toString(dnum));
 820:   }
 821: 
 822:   /**
 823:    * Finds the first instance of a substring in this StringBuilder.
 824:    *
 825:    * @param str String to find
 826:    * @return location (base 0) of the String, or -1 if not found
 827:    * @throws NullPointerException if str is null
 828:    * @see #indexOf(String, int)
 829:    */
 830:   public int indexOf(String str)
 831:   {
 832:     return indexOf(str, 0);
 833:   }
 834: 
 835:   /**
 836:    * Finds the first instance of a String in this StringBuilder, starting at
 837:    * a given index.  If starting index is less than 0, the search starts at
 838:    * the beginning of this String.  If the starting index is greater than the
 839:    * length of this String, or the substring is not found, -1 is returned.
 840:    *
 841:    * @param str String to find
 842:    * @param fromIndex index to start the search
 843:    * @return location (base 0) of the String, or -1 if not found
 844:    * @throws NullPointerException if str is null
 845:    */
 846:   public int indexOf(String str, int fromIndex)
 847:   {
 848:     if (fromIndex < 0)
 849:       fromIndex = 0;
 850:     int limit = count - str.count;
 851:     for ( ; fromIndex <= limit; fromIndex++)
 852:       if (regionMatches(fromIndex, str))
 853:         return fromIndex;
 854:     return -1;
 855:   }
 856: 
 857:   /**
 858:    * Finds the last instance of a substring in this StringBuilder.
 859:    *
 860:    * @param str String to find
 861:    * @return location (base 0) of the String, or -1 if not found
 862:    * @throws NullPointerException if str is null
 863:    * @see #lastIndexOf(String, int)
 864:    */
 865:   public int lastIndexOf(String str)
 866:   {
 867:     return lastIndexOf(str, count - str.count);
 868:   }
 869: 
 870:   /**
 871:    * Finds the last instance of a String in this StringBuilder, starting at a
 872:    * given index.  If starting index is greater than the maximum valid index,
 873:    * then the search begins at the end of this String.  If the starting index
 874:    * is less than zero, or the substring is not found, -1 is returned.
 875:    *
 876:    * @param str String to find
 877:    * @param fromIndex index to start the search
 878:    * @return location (base 0) of the String, or -1 if not found
 879:    * @throws NullPointerException if str is null
 880:    */
 881:   public int lastIndexOf(String str, int fromIndex)
 882:   {
 883:     fromIndex = Math.min(fromIndex, count - str.count);
 884:     for ( ; fromIndex >= 0; fromIndex--)
 885:       if (regionMatches(fromIndex, str))
 886:         return fromIndex;
 887:     return -1;
 888:   }
 889: 
 890:   /**
 891:    * Reverse the characters in this StringBuilder. The same sequence of
 892:    * characters exists, but in the reverse index ordering.
 893:    *
 894:    * @return this <code>StringBuilder</code>
 895:    */
 896:   public StringBuilder reverse()
 897:   {
 898:     // Call ensureCapacity to enforce copy-on-write.
 899:     ensureCapacity(count);
 900:     for (int i = count >> 1, j = count - i; --i >= 0; ++j)
 901:       {
 902:         char c = value[i];
 903:         value[i] = value[j];
 904:         value[j] = c;
 905:       }
 906:     return this;
 907:   }
 908: 
 909:   /**
 910:    * Convert this <code>StringBuilder</code> to a <code>String</code>. The
 911:    * String is composed of the characters currently in this StringBuilder. Note
 912:    * that the result is a copy, and that future modifications to this buffer
 913:    * do not affect the String.
 914:    *
 915:    * @return the characters in this StringBuilder
 916:    */
 917:   public String toString()
 918:   {
 919:     return new String(this);
 920:   }
 921: 
 922:   /**
 923:    * Predicate which determines if a substring of this matches another String
 924:    * starting at a specified offset for each String and continuing for a
 925:    * specified length. This is more efficient than creating a String to call
 926:    * indexOf on.
 927:    *
 928:    * @param toffset index to start comparison at for this String
 929:    * @param other non-null String to compare to region of this
 930:    * @return true if regions match, false otherwise
 931:    * @see #indexOf(String, int)
 932:    * @see #lastIndexOf(String, int)
 933:    * @see String#regionMatches(boolean, int, String, int, int)
 934:    */
 935:   private boolean regionMatches(int toffset, String other)
 936:   {
 937:     int len = other.count;
 938:     int index = other.offset;
 939:     while (--len >= 0)
 940:       if (value[toffset++] != other.value[index++])
 941:         return false;
 942:     return true;
 943:   }
 944: }