1 /*
   2  * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.lang;
  27 
  28 import sun.misc.FloatingDecimal;
  29 import java.util.Arrays;
  30 
  31 /**
  32  * A mutable sequence of characters.
  33  * <p>
  34  * Implements a modifiable string. At any point in time it contains some
  35  * particular sequence of characters, but the length and content of the
  36  * sequence can be changed through certain method calls.
  37  *
  38  * <p>Unless otherwise noted, passing a {@code null} argument to a constructor
  39  * or method in this class will cause a {@link NullPointerException} to be
  40  * thrown.
  41  *
  42  * @author      Michael McCloskey
  43  * @author      Martin Buchholz
  44  * @author      Ulf Zibis
  45  * @since       1.5
  46  */
  47 abstract class AbstractStringBuilder implements Appendable, CharSequence {
  48     /**
  49      * The value is used for character storage.
  50      */
  51     char[] value;
  52 
  53     /**
  54      * The count is the number of characters used.
  55      */
  56     int count;
  57 
  58     /**
  59      * This no-arg constructor is necessary for serialization of subclasses.
  60      */
  61     AbstractStringBuilder() {
  62     }
  63 
  64     /**
  65      * Creates an AbstractStringBuilder of the specified capacity.
  66      */
  67     AbstractStringBuilder(int capacity) {
  68         value = new char[capacity];
  69     }
  70 
  71     /**
  72      * Returns the length (character count).
  73      *
  74      * @return  the length of the sequence of characters currently
  75      *          represented by this object
  76      */
  77     @Override
  78     public int length() {
  79         return count;
  80     }
  81 
  82     /**
  83      * Returns the current capacity. The capacity is the amount of storage
  84      * available for newly inserted characters, beyond which an allocation
  85      * will occur.
  86      *
  87      * @return  the current capacity
  88      */
  89     public int capacity() {
  90         return value.length;
  91     }
  92 
  93     /**
  94      * Ensures that the capacity is at least equal to the specified minimum.
  95      * If the current capacity is less than the argument, then a new internal
  96      * array is allocated with greater capacity. The new capacity is the
  97      * larger of:
  98      * <ul>
  99      * <li>The {@code minimumCapacity} argument.
 100      * <li>Twice the old capacity, plus {@code 2}.
 101      * </ul>
 102      * If the {@code minimumCapacity} argument is nonpositive, this
 103      * method takes no action and simply returns.
 104      * Note that subsequent operations on this object can reduce the
 105      * actual capacity below that requested here.
 106      *
 107      * @param   minimumCapacity   the minimum desired capacity.
 108      */
 109     public void ensureCapacity(int minimumCapacity) {
 110         if (minimumCapacity > 0)
 111             ensureCapacityInternal(minimumCapacity);
 112     }
 113 
 114     /**
 115      * This method has the same contract as ensureCapacity, but is
 116      * never synchronized.
 117      */
 118     private void ensureCapacityInternal(int minimumCapacity) {
 119         // overflow-conscious code
 120         if (minimumCapacity - value.length > 0)
 121             expandCapacity(minimumCapacity);
 122     }
 123 
 124     /**
 125      * This implements the expansion semantics of ensureCapacity with no
 126      * size check or synchronization.
 127      */
 128     void expandCapacity(int minimumCapacity) {
 129         int newCapacity = value.length * 2 + 2;
 130         if (newCapacity - minimumCapacity < 0)
 131             newCapacity = minimumCapacity;
 132         if (newCapacity < 0) {
 133             if (minimumCapacity < 0) // overflow
 134                 throw new OutOfMemoryError();
 135             newCapacity = Integer.MAX_VALUE;
 136         }
 137         value = Arrays.copyOf(value, newCapacity);
 138     }
 139 
 140     /**
 141      * Attempts to reduce storage used for the character sequence.
 142      * If the buffer is larger than necessary to hold its current sequence of
 143      * characters, then it may be resized to become more space efficient.
 144      * Calling this method may, but is not required to, affect the value
 145      * returned by a subsequent call to the {@link #capacity()} method.
 146      */
 147     public void trimToSize() {
 148         if (count < value.length) {
 149             value = Arrays.copyOf(value, count);
 150         }
 151     }
 152 
 153     /**
 154      * Sets the length of the character sequence.
 155      * The sequence is changed to a new character sequence
 156      * whose length is specified by the argument. For every nonnegative
 157      * index <i>k</i> less than {@code newLength}, the character at
 158      * index <i>k</i> in the new character sequence is the same as the
 159      * character at index <i>k</i> in the old sequence if <i>k</i> is less
 160      * than the length of the old character sequence; otherwise, it is the
 161      * null character {@code '\u005Cu0000'}.
 162      *
 163      * In other words, if the {@code newLength} argument is less than
 164      * the current length, the length is changed to the specified length.
 165      * <p>
 166      * If the {@code newLength} argument is greater than or equal
 167      * to the current length, sufficient null characters
 168      * ({@code '\u005Cu0000'}) are appended so that
 169      * length becomes the {@code newLength} argument.
 170      * <p>
 171      * The {@code newLength} argument must be greater than or equal
 172      * to {@code 0}.
 173      *
 174      * @param      newLength   the new length
 175      * @throws     IndexOutOfBoundsException  if the
 176      *               {@code newLength} argument is negative.
 177      */
 178     public void setLength(int newLength) {
 179         if (newLength < 0)
 180             throw new StringIndexOutOfBoundsException(newLength);
 181         ensureCapacityInternal(newLength);
 182 
 183         if (count < newLength) {
 184             Arrays.fill(value, count, newLength, '\0');
 185         }
 186 
 187         count = newLength;
 188     }
 189 
 190     /**
 191      * Returns the {@code char} value in this sequence at the specified index.
 192      * The first {@code char} value is at index {@code 0}, the next at index
 193      * {@code 1}, and so on, as in array indexing.
 194      * <p>
 195      * The index argument must be greater than or equal to
 196      * {@code 0}, and less than the length of this sequence.
 197      *
 198      * <p>If the {@code char} value specified by the index is a
 199      * <a href="Character.html#unicode">surrogate</a>, the surrogate
 200      * value is returned.
 201      *
 202      * @param      index   the index of the desired {@code char} value.
 203      * @return     the {@code char} value at the specified index.
 204      * @throws     IndexOutOfBoundsException  if {@code index} is
 205      *             negative or greater than or equal to {@code length()}.
 206      */
 207     @Override
 208     public char charAt(int index) {
 209         if ((index < 0) || (index >= count))
 210             throw new StringIndexOutOfBoundsException(index);
 211         return value[index];
 212     }
 213 
 214     /**
 215      * Returns the character (Unicode code point) at the specified
 216      * index. The index refers to {@code char} values
 217      * (Unicode code units) and ranges from {@code 0} to
 218      * {@link #length()}{@code  - 1}.
 219      *
 220      * <p> If the {@code char} value specified at the given index
 221      * is in the high-surrogate range, the following index is less
 222      * than the length of this sequence, and the
 223      * {@code char} value at the following index is in the
 224      * low-surrogate range, then the supplementary code point
 225      * corresponding to this surrogate pair is returned. Otherwise,
 226      * the {@code char} value at the given index is returned.
 227      *
 228      * @param      index the index to the {@code char} values
 229      * @return     the code point value of the character at the
 230      *             {@code index}
 231      * @exception  IndexOutOfBoundsException  if the {@code index}
 232      *             argument is negative or not less than the length of this
 233      *             sequence.
 234      */
 235     public int codePointAt(int index) {
 236         if ((index < 0) || (index >= count)) {
 237             throw new StringIndexOutOfBoundsException(index);
 238         }
 239         return Character.codePointAt(value, index);
 240     }
 241 
 242     /**
 243      * Returns the character (Unicode code point) before the specified
 244      * index. The index refers to {@code char} values
 245      * (Unicode code units) and ranges from {@code 1} to {@link
 246      * #length()}.
 247      *
 248      * <p> If the {@code char} value at {@code (index - 1)}
 249      * is in the low-surrogate range, {@code (index - 2)} is not
 250      * negative, and the {@code char} value at {@code (index -
 251      * 2)} is in the high-surrogate range, then the
 252      * supplementary code point value of the surrogate pair is
 253      * returned. If the {@code char} value at {@code index -
 254      * 1} is an unpaired low-surrogate or a high-surrogate, the
 255      * surrogate value is returned.
 256      *
 257      * @param     index the index following the code point that should be returned
 258      * @return    the Unicode code point value before the given index.
 259      * @exception IndexOutOfBoundsException if the {@code index}
 260      *            argument is less than 1 or greater than the length
 261      *            of this sequence.
 262      */
 263     public int codePointBefore(int index) {
 264         int i = index - 1;
 265         if ((i < 0) || (i >= count)) {
 266             throw new StringIndexOutOfBoundsException(index);
 267         }
 268         return Character.codePointBefore(value, index);
 269     }
 270 
 271     /**
 272      * Returns the number of Unicode code points in the specified text
 273      * range of this sequence. The text range begins at the specified
 274      * {@code beginIndex} and extends to the {@code char} at
 275      * index {@code endIndex - 1}. Thus the length (in
 276      * {@code char}s) of the text range is
 277      * {@code endIndex-beginIndex}. Unpaired surrogates within
 278      * this sequence count as one code point each.
 279      *
 280      * @param beginIndex the index to the first {@code char} of
 281      * the text range.
 282      * @param endIndex the index after the last {@code char} of
 283      * the text range.
 284      * @return the number of Unicode code points in the specified text
 285      * range
 286      * @exception IndexOutOfBoundsException if the
 287      * {@code beginIndex} is negative, or {@code endIndex}
 288      * is larger than the length of this sequence, or
 289      * {@code beginIndex} is larger than {@code endIndex}.
 290      */
 291     public int codePointCount(int beginIndex, int endIndex) {
 292         if (beginIndex < 0 || endIndex > count || beginIndex > endIndex) {
 293             throw new IndexOutOfBoundsException();
 294         }
 295         return Character.codePointCountImpl(value, beginIndex, endIndex-beginIndex);
 296     }
 297 
 298     /**
 299      * Returns the index within this sequence that is offset from the
 300      * given {@code index} by {@code codePointOffset} code
 301      * points. Unpaired surrogates within the text range given by
 302      * {@code index} and {@code codePointOffset} count as
 303      * one code point each.
 304      *
 305      * @param index the index to be offset
 306      * @param codePointOffset the offset in code points
 307      * @return the index within this sequence
 308      * @exception IndexOutOfBoundsException if {@code index}
 309      *   is negative or larger then the length of this sequence,
 310      *   or if {@code codePointOffset} is positive and the subsequence
 311      *   starting with {@code index} has fewer than
 312      *   {@code codePointOffset} code points,
 313      *   or if {@code codePointOffset} is negative and the subsequence
 314      *   before {@code index} has fewer than the absolute value of
 315      *   {@code codePointOffset} code points.
 316      */
 317     public int offsetByCodePoints(int index, int codePointOffset) {
 318         if (index < 0 || index > count) {
 319             throw new IndexOutOfBoundsException();
 320         }
 321         return Character.offsetByCodePointsImpl(value, 0, count,
 322                                                 index, codePointOffset);
 323     }
 324 
 325     /**
 326      * Characters are copied from this sequence into the
 327      * destination character array {@code dst}. The first character to
 328      * be copied is at index {@code srcBegin}; the last character to
 329      * be copied is at index {@code srcEnd-1}. The total number of
 330      * characters to be copied is {@code srcEnd-srcBegin}. The
 331      * characters are copied into the subarray of {@code dst} starting
 332      * at index {@code dstBegin} and ending at index:
 333      * <p><blockquote><pre>
 334      * dstbegin + (srcEnd-srcBegin) - 1
 335      * </pre></blockquote>
 336      *
 337      * @param      srcBegin   start copying at this offset.
 338      * @param      srcEnd     stop copying at this offset.
 339      * @param      dst        the array to copy the data into.
 340      * @param      dstBegin   offset into {@code dst}.
 341      * @throws     IndexOutOfBoundsException  if any of the following is true:
 342      *             <ul>
 343      *             <li>{@code srcBegin} is negative
 344      *             <li>{@code dstBegin} is negative
 345      *             <li>the {@code srcBegin} argument is greater than
 346      *             the {@code srcEnd} argument.
 347      *             <li>{@code srcEnd} is greater than
 348      *             {@code this.length()}.
 349      *             <li>{@code dstBegin+srcEnd-srcBegin} is greater than
 350      *             {@code dst.length}
 351      *             </ul>
 352      */
 353     public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)
 354     {
 355         if (srcBegin < 0)
 356             throw new StringIndexOutOfBoundsException(srcBegin);
 357         if ((srcEnd < 0) || (srcEnd > count))
 358             throw new StringIndexOutOfBoundsException(srcEnd);
 359         if (srcBegin > srcEnd)
 360             throw new StringIndexOutOfBoundsException("srcBegin > srcEnd");
 361         System.arraycopy(value, srcBegin, dst, dstBegin, srcEnd - srcBegin);
 362     }
 363 
 364     /**
 365      * The character at the specified index is set to {@code ch}. This
 366      * sequence is altered to represent a new character sequence that is
 367      * identical to the old character sequence, except that it contains the
 368      * character {@code ch} at position {@code index}.
 369      * <p>
 370      * The index argument must be greater than or equal to
 371      * {@code 0}, and less than the length of this sequence.
 372      *
 373      * @param      index   the index of the character to modify.
 374      * @param      ch      the new character.
 375      * @throws     IndexOutOfBoundsException  if {@code index} is
 376      *             negative or greater than or equal to {@code length()}.
 377      */
 378     public void setCharAt(int index, char ch) {
 379         if ((index < 0) || (index >= count))
 380             throw new StringIndexOutOfBoundsException(index);
 381         value[index] = ch;
 382     }
 383 
 384     /**
 385      * Appends the string representation of the {@code Object} argument.
 386      * <p>
 387      * The overall effect is exactly as if the argument were converted
 388      * to a string by the method {@link String#valueOf(Object)},
 389      * and the characters of that string were then
 390      * {@link #append(String) appended} to this character sequence.
 391      *
 392      * @param   obj   an {@code Object}.
 393      * @return  a reference to this object.
 394      */
 395     public AbstractStringBuilder append(Object obj) {
 396         return append(String.valueOf(obj));
 397     }
 398 
 399     /**
 400      * Appends the specified string to this character sequence.
 401      * <p>
 402      * The characters of the {@code String} argument are appended, in
 403      * order, increasing the length of this sequence by the length of the
 404      * argument. If {@code str} is {@code null}, then the four
 405      * characters {@code "null"} are appended.
 406      * <p>
 407      * Let <i>n</i> be the length of this character sequence just prior to
 408      * execution of the {@code append} method. Then the character at
 409      * index <i>k</i> in the new character sequence is equal to the character
 410      * at index <i>k</i> in the old character sequence, if <i>k</i> is less
 411      * than <i>n</i>; otherwise, it is equal to the character at index
 412      * <i>k-n</i> in the argument {@code str}.
 413      *
 414      * @param   str   a string.
 415      * @return  a reference to this object.
 416      */
 417     public AbstractStringBuilder append(String str) {
 418         if (str == null) str = "null";
 419         int len = str.length();
 420         ensureCapacityInternal(count + len);
 421         str.getChars(0, len, value, count);
 422         count += len;
 423         return this;
 424     }
 425 
 426     // Documentation in subclasses because of synchro difference
 427     public AbstractStringBuilder append(StringBuffer sb) {
 428         if (sb == null)
 429             return append("null");
 430         int len = sb.length();
 431         ensureCapacityInternal(count + len);
 432         sb.getChars(0, len, value, count);
 433         count += len;
 434         return this;
 435     }
 436 
 437     /**
 438      * @since 1.8
 439      */
 440     AbstractStringBuilder append(AbstractStringBuilder asb) {
 441         if (asb == null)
 442             return append("null");
 443         int len = asb.length();
 444         ensureCapacityInternal(count + len);
 445         asb.getChars(0, len, value, count);
 446         count += len;
 447         return this;
 448     }
 449 
 450     // Documentation in subclasses because of synchro difference
 451     @Override
 452     public AbstractStringBuilder append(CharSequence s) {
 453         if (s == null)
 454             s = "null";
 455         if (s instanceof String)
 456             return this.append((String)s);
 457         if (s instanceof AbstractStringBuilder)
 458             return this.append((AbstractStringBuilder)s);
 459 
 460         return this.append(s, 0, s.length());
 461     }
 462 
 463     /**
 464      * Appends a subsequence of the specified {@code CharSequence} to this
 465      * sequence.
 466      * <p>
 467      * Characters of the argument {@code s}, starting at
 468      * index {@code start}, are appended, in order, to the contents of
 469      * this sequence up to the (exclusive) index {@code end}. The length
 470      * of this sequence is increased by the value of {@code end - start}.
 471      * <p>
 472      * Let <i>n</i> be the length of this character sequence just prior to
 473      * execution of the {@code append} method. Then the character at
 474      * index <i>k</i> in this character sequence becomes equal to the
 475      * character at index <i>k</i> in this sequence, if <i>k</i> is less than
 476      * <i>n</i>; otherwise, it is equal to the character at index
 477      * <i>k+start-n</i> in the argument {@code s}.
 478      * <p>
 479      * If {@code s} is {@code null}, then this method appends
 480      * characters as if the s parameter was a sequence containing the four
 481      * characters {@code "null"}.
 482      *
 483      * @param   s the sequence to append.
 484      * @param   start   the starting index of the subsequence to be appended.
 485      * @param   end     the end index of the subsequence to be appended.
 486      * @return  a reference to this object.
 487      * @throws     IndexOutOfBoundsException if
 488      *             {@code start} is negative, or
 489      *             {@code start} is greater than {@code end} or
 490      *             {@code end} is greater than {@code s.length()}
 491      */
 492     @Override
 493     public AbstractStringBuilder append(CharSequence s, int start, int end) {
 494         if (s == null)
 495             s = "null";
 496         if ((start < 0) || (start > end) || (end > s.length()))
 497             throw new IndexOutOfBoundsException(
 498                 "start " + start + ", end " + end + ", s.length() "
 499                 + s.length());
 500         int len = end - start;
 501         ensureCapacityInternal(count + len);
 502         for (int i = start, j = count; i < end; i++, j++)
 503             value[j] = s.charAt(i);
 504         count += len;
 505         return this;
 506     }
 507 
 508     /**
 509      * Appends the string representation of the {@code char} array
 510      * argument to this sequence.
 511      * <p>
 512      * The characters of the array argument are appended, in order, to
 513      * the contents of this sequence. The length of this sequence
 514      * increases by the length of the argument.
 515      * <p>
 516      * The overall effect is exactly as if the argument were converted
 517      * to a string by the method {@link String#valueOf(char[])},
 518      * and the characters of that string were then
 519      * {@link #append(String) appended} to this character sequence.
 520      *
 521      * @param   str   the characters to be appended.
 522      * @return  a reference to this object.
 523      */
 524     public AbstractStringBuilder append(char[] str) {
 525         int len = str.length;
 526         ensureCapacityInternal(count + len);
 527         System.arraycopy(str, 0, value, count, len);
 528         count += len;
 529         return this;
 530     }
 531 
 532     /**
 533      * Appends the string representation of a subarray of the
 534      * {@code char} array argument to this sequence.
 535      * <p>
 536      * Characters of the {@code char} array {@code str}, starting at
 537      * index {@code offset}, are appended, in order, to the contents
 538      * of this sequence. The length of this sequence increases
 539      * by the value of {@code len}.
 540      * <p>
 541      * The overall effect is exactly as if the arguments were converted
 542      * to a string by the method {@link String#valueOf(char[],int,int)},
 543      * and the characters of that string were then
 544      * {@link #append(String) appended} to this character sequence.
 545      *
 546      * @param   str      the characters to be appended.
 547      * @param   offset   the index of the first {@code char} to append.
 548      * @param   len      the number of {@code char}s to append.
 549      * @return  a reference to this object.
 550      * @throws IndexOutOfBoundsException
 551      *         if {@code offset < 0} or {@code len < 0}
 552      *         or {@code offset+len > str.length}
 553      */
 554     public AbstractStringBuilder append(char str[], int offset, int len) {
 555         if (len > 0)                // let arraycopy report AIOOBE for len < 0
 556             ensureCapacityInternal(count + len);
 557         System.arraycopy(str, offset, value, count, len);
 558         count += len;
 559         return this;
 560     }
 561 
 562     /**
 563      * Appends the string representation of the {@code boolean}
 564      * argument to the sequence.
 565      * <p>
 566      * The overall effect is exactly as if the argument were converted
 567      * to a string by the method {@link String#valueOf(boolean)},
 568      * and the characters of that string were then
 569      * {@link #append(String) appended} to this character sequence.
 570      *
 571      * @param   b   a {@code boolean}.
 572      * @return  a reference to this object.
 573      */
 574     public AbstractStringBuilder append(boolean b) {
 575         if (b) {
 576             ensureCapacityInternal(count + 4);
 577             value[count++] = 't';
 578             value[count++] = 'r';
 579             value[count++] = 'u';
 580             value[count++] = 'e';
 581         } else {
 582             ensureCapacityInternal(count + 5);
 583             value[count++] = 'f';
 584             value[count++] = 'a';
 585             value[count++] = 'l';
 586             value[count++] = 's';
 587             value[count++] = 'e';
 588         }
 589         return this;
 590     }
 591 
 592     /**
 593      * Appends the string representation of the {@code char}
 594      * argument to this sequence.
 595      * <p>
 596      * The argument is appended to the contents of this sequence.
 597      * The length of this sequence increases by {@code 1}.
 598      * <p>
 599      * The overall effect is exactly as if the argument were converted
 600      * to a string by the method {@link String#valueOf(char)},
 601      * and the character in that string were then
 602      * {@link #append(String) appended} to this character sequence.
 603      *
 604      * @param   c   a {@code char}.
 605      * @return  a reference to this object.
 606      */
 607     @Override
 608     public AbstractStringBuilder append(char c) {
 609         ensureCapacityInternal(count + 1);
 610         value[count++] = c;
 611         return this;
 612     }
 613 
 614     /**
 615      * Appends the string representation of the {@code int}
 616      * argument to this sequence.
 617      * <p>
 618      * The overall effect is exactly as if the argument were converted
 619      * to a string by the method {@link String#valueOf(int)},
 620      * and the characters of that string were then
 621      * {@link #append(String) appended} to this character sequence.
 622      *
 623      * @param   i   an {@code int}.
 624      * @return  a reference to this object.
 625      */
 626     public AbstractStringBuilder append(int i) {
 627         if (i == Integer.MIN_VALUE) {
 628             append("-2147483648");
 629             return this;
 630         }
 631         int appendedLength = (i < 0) ? Integer.stringSize(-i) + 1
 632                                      : Integer.stringSize(i);
 633         int spaceNeeded = count + appendedLength;
 634         ensureCapacityInternal(spaceNeeded);
 635         Integer.getChars(i, spaceNeeded, value);
 636         count = spaceNeeded;
 637         return this;
 638     }
 639 
 640     /**
 641      * Appends the string representation of the {@code long}
 642      * argument to this sequence.
 643      * <p>
 644      * The overall effect is exactly as if the argument were converted
 645      * to a string by the method {@link String#valueOf(long)},
 646      * and the characters of that string were then
 647      * {@link #append(String) appended} to this character sequence.
 648      *
 649      * @param   l   a {@code long}.
 650      * @return  a reference to this object.
 651      */
 652     public AbstractStringBuilder append(long l) {
 653         if (l == Long.MIN_VALUE) {
 654             append("-9223372036854775808");
 655             return this;
 656         }
 657         int appendedLength = (l < 0) ? Long.stringSize(-l) + 1
 658                                      : Long.stringSize(l);
 659         int spaceNeeded = count + appendedLength;
 660         ensureCapacityInternal(spaceNeeded);
 661         Long.getChars(l, spaceNeeded, value);
 662         count = spaceNeeded;
 663         return this;
 664     }
 665 
 666     /**
 667      * Appends the string representation of the {@code float}
 668      * argument to this sequence.
 669      * <p>
 670      * The overall effect is exactly as if the argument were converted
 671      * to a string by the method {@link String#valueOf(float)},
 672      * and the characters of that string were then
 673      * {@link #append(String) appended} to this character sequence.
 674      *
 675      * @param   f   a {@code float}.
 676      * @return  a reference to this object.
 677      */
 678     public AbstractStringBuilder append(float f) {
 679         new FloatingDecimal(f).appendTo(this);
 680         return this;
 681     }
 682 
 683     /**
 684      * Appends the string representation of the {@code double}
 685      * argument to this sequence.
 686      * <p>
 687      * The overall effect is exactly as if the argument were converted
 688      * to a string by the method {@link String#valueOf(double)},
 689      * and the characters of that string were then
 690      * {@link #append(String) appended} to this character sequence.
 691      *
 692      * @param   d   a {@code double}.
 693      * @return  a reference to this object.
 694      */
 695     public AbstractStringBuilder append(double d) {
 696         new FloatingDecimal(d).appendTo(this);
 697         return this;
 698     }
 699 
 700     /**
 701      * Removes the characters in a substring of this sequence.
 702      * The substring begins at the specified {@code start} and extends to
 703      * the character at index {@code end - 1} or to the end of the
 704      * sequence if no such character exists. If
 705      * {@code start} is equal to {@code end}, no changes are made.
 706      *
 707      * @param      start  The beginning index, inclusive.
 708      * @param      end    The ending index, exclusive.
 709      * @return     This object.
 710      * @throws     StringIndexOutOfBoundsException  if {@code start}
 711      *             is negative, greater than {@code length()}, or
 712      *             greater than {@code end}.
 713      */
 714     public AbstractStringBuilder delete(int start, int end) {
 715         if (start < 0)
 716             throw new StringIndexOutOfBoundsException(start);
 717         if (end > count)
 718             end = count;
 719         if (start > end)
 720             throw new StringIndexOutOfBoundsException();
 721         int len = end - start;
 722         if (len > 0) {
 723             System.arraycopy(value, start+len, value, start, count-end);
 724             count -= len;
 725         }
 726         return this;
 727     }
 728 
 729     /**
 730      * Appends the string representation of the {@code codePoint}
 731      * argument to this sequence.
 732      *
 733      * <p> The argument is appended to the contents of this sequence.
 734      * The length of this sequence increases by
 735      * {@link Character#charCount(int) Character.charCount(codePoint)}.
 736      *
 737      * <p> The overall effect is exactly as if the argument were
 738      * converted to a {@code char} array by the method
 739      * {@link Character#toChars(int)} and the character in that array
 740      * were then {@link #append(char[]) appended} to this character
 741      * sequence.
 742      *
 743      * @param   codePoint   a Unicode code point
 744      * @return  a reference to this object.
 745      * @exception IllegalArgumentException if the specified
 746      * {@code codePoint} isn't a valid Unicode code point
 747      */
 748     public AbstractStringBuilder appendCodePoint(int codePoint) {
 749         final int count = this.count;
 750 
 751         if (Character.isBmpCodePoint(codePoint)) {
 752             ensureCapacityInternal(count + 1);
 753             value[count] = (char) codePoint;
 754             this.count = count + 1;
 755         } else if (Character.isValidCodePoint(codePoint)) {
 756             ensureCapacityInternal(count + 2);
 757             Character.toSurrogates(codePoint, value, count);
 758             this.count = count + 2;
 759         } else {
 760             throw new IllegalArgumentException();
 761         }
 762         return this;
 763     }
 764 
 765     /**
 766      * Removes the {@code char} at the specified position in this
 767      * sequence. This sequence is shortened by one {@code char}.
 768      *
 769      * <p>Note: If the character at the given index is a supplementary
 770      * character, this method does not remove the entire character. If
 771      * correct handling of supplementary characters is required,
 772      * determine the number of {@code char}s to remove by calling
 773      * {@code Character.charCount(thisSequence.codePointAt(index))},
 774      * where {@code thisSequence} is this sequence.
 775      *
 776      * @param       index  Index of {@code char} to remove
 777      * @return      This object.
 778      * @throws      StringIndexOutOfBoundsException  if the {@code index}
 779      *              is negative or greater than or equal to
 780      *              {@code length()}.
 781      */
 782     public AbstractStringBuilder deleteCharAt(int index) {
 783         if ((index < 0) || (index >= count))
 784             throw new StringIndexOutOfBoundsException(index);
 785         System.arraycopy(value, index+1, value, index, count-index-1);
 786         count--;
 787         return this;
 788     }
 789 
 790     /**
 791      * Replaces the characters in a substring of this sequence
 792      * with characters in the specified {@code String}. The substring
 793      * begins at the specified {@code start} and extends to the character
 794      * at index {@code end - 1} or to the end of the
 795      * sequence if no such character exists. First the
 796      * characters in the substring are removed and then the specified
 797      * {@code String} is inserted at {@code start}. (This
 798      * sequence will be lengthened to accommodate the
 799      * specified String if necessary.)
 800      *
 801      * @param      start    The beginning index, inclusive.
 802      * @param      end      The ending index, exclusive.
 803      * @param      str   String that will replace previous contents.
 804      * @return     This object.
 805      * @throws     StringIndexOutOfBoundsException  if {@code start}
 806      *             is negative, greater than {@code length()}, or
 807      *             greater than {@code end}.
 808      */
 809     public AbstractStringBuilder replace(int start, int end, String str) {
 810         if (start < 0)
 811             throw new StringIndexOutOfBoundsException(start);
 812         if (start > count)
 813             throw new StringIndexOutOfBoundsException("start > length()");
 814         if (start > end)
 815             throw new StringIndexOutOfBoundsException("start > end");
 816 
 817         if (end > count)
 818             end = count;
 819         int len = str.length();
 820         int newCount = count + len - (end - start);
 821         ensureCapacityInternal(newCount);
 822 
 823         System.arraycopy(value, end, value, start + len, count - end);
 824         str.getChars(value, start);
 825         count = newCount;
 826         return this;
 827     }
 828 
 829     /**
 830      * Returns a new {@code String} that contains a subsequence of
 831      * characters currently contained in this character sequence. The
 832      * substring begins at the specified index and extends to the end of
 833      * this sequence.
 834      *
 835      * @param      start    The beginning index, inclusive.
 836      * @return     The new string.
 837      * @throws     StringIndexOutOfBoundsException  if {@code start} is
 838      *             less than zero, or greater than the length of this object.
 839      */
 840     public String substring(int start) {
 841         return substring(start, count);
 842     }
 843 
 844     /**
 845      * Returns a new character sequence that is a subsequence of this sequence.
 846      *
 847      * <p> An invocation of this method of the form
 848      *
 849      * <blockquote><pre>
 850      * sb.subSequence(begin,&nbsp;end)</pre></blockquote>
 851      *
 852      * behaves in exactly the same way as the invocation
 853      *
 854      * <blockquote><pre>
 855      * sb.substring(begin,&nbsp;end)</pre></blockquote>
 856      *
 857      * This method is provided so that this class can
 858      * implement the {@link CharSequence} interface. </p>
 859      *
 860      * @param      start   the start index, inclusive.
 861      * @param      end     the end index, exclusive.
 862      * @return     the specified subsequence.
 863      *
 864      * @throws  IndexOutOfBoundsException
 865      *          if {@code start} or {@code end} are negative,
 866      *          if {@code end} is greater than {@code length()},
 867      *          or if {@code start} is greater than {@code end}
 868      * @spec JSR-51
 869      */
 870     @Override
 871     public CharSequence subSequence(int start, int end) {
 872         return substring(start, end);
 873     }
 874 
 875     /**
 876      * Returns a new {@code String} that contains a subsequence of
 877      * characters currently contained in this sequence. The
 878      * substring begins at the specified {@code start} and
 879      * extends to the character at index {@code end - 1}.
 880      *
 881      * @param      start    The beginning index, inclusive.
 882      * @param      end      The ending index, exclusive.
 883      * @return     The new string.
 884      * @throws     StringIndexOutOfBoundsException  if {@code start}
 885      *             or {@code end} are negative or greater than
 886      *             {@code length()}, or {@code start} is
 887      *             greater than {@code end}.
 888      */
 889     public String substring(int start, int end) {
 890         if (start < 0)
 891             throw new StringIndexOutOfBoundsException(start);
 892         if (end > count)
 893             throw new StringIndexOutOfBoundsException(end);
 894         if (start > end)
 895             throw new StringIndexOutOfBoundsException(end - start);
 896         return new String(value, start, end - start);
 897     }
 898 
 899     /**
 900      * Inserts the string representation of a subarray of the {@code str}
 901      * array argument into this sequence. The subarray begins at the
 902      * specified {@code offset} and extends {@code len} {@code char}s.
 903      * The characters of the subarray are inserted into this sequence at
 904      * the position indicated by {@code index}. The length of this
 905      * sequence increases by {@code len} {@code char}s.
 906      *
 907      * @param      index    position at which to insert subarray.
 908      * @param      str       A {@code char} array.
 909      * @param      offset   the index of the first {@code char} in subarray to
 910      *             be inserted.
 911      * @param      len      the number of {@code char}s in the subarray to
 912      *             be inserted.
 913      * @return     This object
 914      * @throws     StringIndexOutOfBoundsException  if {@code index}
 915      *             is negative or greater than {@code length()}, or
 916      *             {@code offset} or {@code len} are negative, or
 917      *             {@code (offset+len)} is greater than
 918      *             {@code str.length}.
 919      */
 920     public AbstractStringBuilder insert(int index, char[] str, int offset,
 921                                         int len)
 922     {
 923         if ((index < 0) || (index > length()))
 924             throw new StringIndexOutOfBoundsException(index);
 925         if ((offset < 0) || (len < 0) || (offset > str.length - len))
 926             throw new StringIndexOutOfBoundsException(
 927                 "offset " + offset + ", len " + len + ", str.length "
 928                 + str.length);
 929         ensureCapacityInternal(count + len);
 930         System.arraycopy(value, index, value, index + len, count - index);
 931         System.arraycopy(str, offset, value, index, len);
 932         count += len;
 933         return this;
 934     }
 935 
 936     /**
 937      * Inserts the string representation of the {@code Object}
 938      * argument into this character sequence.
 939      * <p>
 940      * The overall effect is exactly as if the second argument were
 941      * converted to a string by the method {@link String#valueOf(Object)},
 942      * and the characters of that string were then
 943      * {@link #insert(int,String) inserted} into this character
 944      * sequence at the indicated offset.
 945      * <p>
 946      * The {@code offset} argument must be greater than or equal to
 947      * {@code 0}, and less than or equal to the {@linkplain #length() length}
 948      * of this sequence.
 949      *
 950      * @param      offset   the offset.
 951      * @param      obj      an {@code Object}.
 952      * @return     a reference to this object.
 953      * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
 954      */
 955     public AbstractStringBuilder insert(int offset, Object obj) {
 956         return insert(offset, String.valueOf(obj));
 957     }
 958 
 959     /**
 960      * Inserts the string into this character sequence.
 961      * <p>
 962      * The characters of the {@code String} argument are inserted, in
 963      * order, into this sequence at the indicated offset, moving up any
 964      * characters originally above that position and increasing the length
 965      * of this sequence by the length of the argument. If
 966      * {@code str} is {@code null}, then the four characters
 967      * {@code "null"} are inserted into this sequence.
 968      * <p>
 969      * The character at index <i>k</i> in the new character sequence is
 970      * equal to:
 971      * <ul>
 972      * <li>the character at index <i>k</i> in the old character sequence, if
 973      * <i>k</i> is less than {@code offset}
 974      * <li>the character at index <i>k</i>{@code -offset} in the
 975      * argument {@code str}, if <i>k</i> is not less than
 976      * {@code offset} but is less than {@code offset+str.length()}
 977      * <li>the character at index <i>k</i>{@code -str.length()} in the
 978      * old character sequence, if <i>k</i> is not less than
 979      * {@code offset+str.length()}
 980      * </ul><p>
 981      * The {@code offset} argument must be greater than or equal to
 982      * {@code 0}, and less than or equal to the {@linkplain #length() length}
 983      * of this sequence.
 984      *
 985      * @param      offset   the offset.
 986      * @param      str      a string.
 987      * @return     a reference to this object.
 988      * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
 989      */
 990     public AbstractStringBuilder insert(int offset, String str) {
 991         if ((offset < 0) || (offset > length()))
 992             throw new StringIndexOutOfBoundsException(offset);
 993         if (str == null)
 994             str = "null";
 995         int len = str.length();
 996         ensureCapacityInternal(count + len);
 997         System.arraycopy(value, offset, value, offset + len, count - offset);
 998         str.getChars(value, offset);
 999         count += len;
1000         return this;
1001     }
1002 
1003     /**
1004      * Inserts the string representation of the {@code char} array
1005      * argument into this sequence.
1006      * <p>
1007      * The characters of the array argument are inserted into the
1008      * contents of this sequence at the position indicated by
1009      * {@code offset}. The length of this sequence increases by
1010      * the length of the argument.
1011      * <p>
1012      * The overall effect is exactly as if the second argument were
1013      * converted to a string by the method {@link String#valueOf(char[])},
1014      * and the characters of that string were then
1015      * {@link #insert(int,String) inserted} into this character
1016      * sequence at the indicated offset.
1017      * <p>
1018      * The {@code offset} argument must be greater than or equal to
1019      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1020      * of this sequence.
1021      *
1022      * @param      offset   the offset.
1023      * @param      str      a character array.
1024      * @return     a reference to this object.
1025      * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
1026      */
1027     public AbstractStringBuilder insert(int offset, char[] str) {
1028         if ((offset < 0) || (offset > length()))
1029             throw new StringIndexOutOfBoundsException(offset);
1030         int len = str.length;
1031         ensureCapacityInternal(count + len);
1032         System.arraycopy(value, offset, value, offset + len, count - offset);
1033         System.arraycopy(str, 0, value, offset, len);
1034         count += len;
1035         return this;
1036     }
1037 
1038     /**
1039      * Inserts the specified {@code CharSequence} into this sequence.
1040      * <p>
1041      * The characters of the {@code CharSequence} argument are inserted,
1042      * in order, into this sequence at the indicated offset, moving up
1043      * any characters originally above that position and increasing the length
1044      * of this sequence by the length of the argument s.
1045      * <p>
1046      * The result of this method is exactly the same as if it were an
1047      * invocation of this object's
1048      * {@link #insert(int,CharSequence,int,int) insert}(dstOffset, s, 0, s.length())
1049      * method.
1050      *
1051      * <p>If {@code s} is {@code null}, then the four characters
1052      * {@code "null"} are inserted into this sequence.
1053      *
1054      * @param      dstOffset   the offset.
1055      * @param      s the sequence to be inserted
1056      * @return     a reference to this object.
1057      * @throws     IndexOutOfBoundsException  if the offset is invalid.
1058      */
1059     public AbstractStringBuilder insert(int dstOffset, CharSequence s) {
1060         if (s == null)
1061             s = "null";
1062         if (s instanceof String)
1063             return this.insert(dstOffset, (String)s);
1064         return this.insert(dstOffset, s, 0, s.length());
1065     }
1066 
1067     /**
1068      * Inserts a subsequence of the specified {@code CharSequence} into
1069      * this sequence.
1070      * <p>
1071      * The subsequence of the argument {@code s} specified by
1072      * {@code start} and {@code end} are inserted,
1073      * in order, into this sequence at the specified destination offset, moving
1074      * up any characters originally above that position. The length of this
1075      * sequence is increased by {@code end - start}.
1076      * <p>
1077      * The character at index <i>k</i> in this sequence becomes equal to:
1078      * <ul>
1079      * <li>the character at index <i>k</i> in this sequence, if
1080      * <i>k</i> is less than {@code dstOffset}
1081      * <li>the character at index <i>k</i>{@code +start-dstOffset} in
1082      * the argument {@code s}, if <i>k</i> is greater than or equal to
1083      * {@code dstOffset} but is less than {@code dstOffset+end-start}
1084      * <li>the character at index <i>k</i>{@code -(end-start)} in this
1085      * sequence, if <i>k</i> is greater than or equal to
1086      * {@code dstOffset+end-start}
1087      * </ul><p>
1088      * The {@code dstOffset} argument must be greater than or equal to
1089      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1090      * of this sequence.
1091      * <p>The start argument must be nonnegative, and not greater than
1092      * {@code end}.
1093      * <p>The end argument must be greater than or equal to
1094      * {@code start}, and less than or equal to the length of s.
1095      *
1096      * <p>If {@code s} is {@code null}, then this method inserts
1097      * characters as if the s parameter was a sequence containing the four
1098      * characters {@code "null"}.
1099      *
1100      * @param      dstOffset   the offset in this sequence.
1101      * @param      s       the sequence to be inserted.
1102      * @param      start   the starting index of the subsequence to be inserted.
1103      * @param      end     the end index of the subsequence to be inserted.
1104      * @return     a reference to this object.
1105      * @throws     IndexOutOfBoundsException  if {@code dstOffset}
1106      *             is negative or greater than {@code this.length()}, or
1107      *              {@code start} or {@code end} are negative, or
1108      *              {@code start} is greater than {@code end} or
1109      *              {@code end} is greater than {@code s.length()}
1110      */
1111      public AbstractStringBuilder insert(int dstOffset, CharSequence s,
1112                                          int start, int end) {
1113         if (s == null)
1114             s = "null";
1115         if ((dstOffset < 0) || (dstOffset > this.length()))
1116             throw new IndexOutOfBoundsException("dstOffset "+dstOffset);
1117         if ((start < 0) || (end < 0) || (start > end) || (end > s.length()))
1118             throw new IndexOutOfBoundsException(
1119                 "start " + start + ", end " + end + ", s.length() "
1120                 + s.length());
1121         int len = end - start;
1122         ensureCapacityInternal(count + len);
1123         System.arraycopy(value, dstOffset, value, dstOffset + len,
1124                          count - dstOffset);
1125         for (int i=start; i<end; i++)
1126             value[dstOffset++] = s.charAt(i);
1127         count += len;
1128         return this;
1129     }
1130 
1131     /**
1132      * Inserts the string representation of the {@code boolean}
1133      * argument into this sequence.
1134      * <p>
1135      * The overall effect is exactly as if the second argument were
1136      * converted to a string by the method {@link String#valueOf(boolean)},
1137      * and the characters of that string were then
1138      * {@link #insert(int,String) inserted} into this character
1139      * sequence at the indicated offset.
1140      * <p>
1141      * The {@code offset} argument must be greater than or equal to
1142      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1143      * of this sequence.
1144      *
1145      * @param      offset   the offset.
1146      * @param      b        a {@code boolean}.
1147      * @return     a reference to this object.
1148      * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
1149      */
1150     public AbstractStringBuilder insert(int offset, boolean b) {
1151         return insert(offset, String.valueOf(b));
1152     }
1153 
1154     /**
1155      * Inserts the string representation of the {@code char}
1156      * argument into this sequence.
1157      * <p>
1158      * The overall effect is exactly as if the second argument were
1159      * converted to a string by the method {@link String#valueOf(char)},
1160      * and the character in that string were then
1161      * {@link #insert(int,String) inserted} into this character
1162      * sequence at the indicated offset.
1163      * <p>
1164      * The {@code offset} argument must be greater than or equal to
1165      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1166      * of this sequence.
1167      *
1168      * @param      offset   the offset.
1169      * @param      c        a {@code char}.
1170      * @return     a reference to this object.
1171      * @throws     IndexOutOfBoundsException  if the offset is invalid.
1172      */
1173     public AbstractStringBuilder insert(int offset, char c) {
1174         ensureCapacityInternal(count + 1);
1175         System.arraycopy(value, offset, value, offset + 1, count - offset);
1176         value[offset] = c;
1177         count += 1;
1178         return this;
1179     }
1180 
1181     /**
1182      * Inserts the string representation of the second {@code int}
1183      * argument into this sequence.
1184      * <p>
1185      * The overall effect is exactly as if the second argument were
1186      * converted to a string by the method {@link String#valueOf(int)},
1187      * and the characters of that string were then
1188      * {@link #insert(int,String) inserted} into this character
1189      * sequence at the indicated offset.
1190      * <p>
1191      * The {@code offset} argument must be greater than or equal to
1192      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1193      * of this sequence.
1194      *
1195      * @param      offset   the offset.
1196      * @param      i        an {@code int}.
1197      * @return     a reference to this object.
1198      * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
1199      */
1200     public AbstractStringBuilder insert(int offset, int i) {
1201         return insert(offset, String.valueOf(i));
1202     }
1203 
1204     /**
1205      * Inserts the string representation of the {@code long}
1206      * argument into this sequence.
1207      * <p>
1208      * The overall effect is exactly as if the second argument were
1209      * converted to a string by the method {@link String#valueOf(long)},
1210      * and the characters of that string were then
1211      * {@link #insert(int,String) inserted} into this character
1212      * sequence at the indicated offset.
1213      * <p>
1214      * The {@code offset} argument must be greater than or equal to
1215      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1216      * of this sequence.
1217      *
1218      * @param      offset   the offset.
1219      * @param      l        a {@code long}.
1220      * @return     a reference to this object.
1221      * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
1222      */
1223     public AbstractStringBuilder insert(int offset, long l) {
1224         return insert(offset, String.valueOf(l));
1225     }
1226 
1227     /**
1228      * Inserts the string representation of the {@code float}
1229      * argument into this sequence.
1230      * <p>
1231      * The overall effect is exactly as if the second argument were
1232      * converted to a string by the method {@link String#valueOf(float)},
1233      * and the characters of that string were then
1234      * {@link #insert(int,String) inserted} into this character
1235      * sequence at the indicated offset.
1236      * <p>
1237      * The {@code offset} argument must be greater than or equal to
1238      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1239      * of this sequence.
1240      *
1241      * @param      offset   the offset.
1242      * @param      f        a {@code float}.
1243      * @return     a reference to this object.
1244      * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
1245      */
1246     public AbstractStringBuilder insert(int offset, float f) {
1247         return insert(offset, String.valueOf(f));
1248     }
1249 
1250     /**
1251      * Inserts the string representation of the {@code double}
1252      * argument into this sequence.
1253      * <p>
1254      * The overall effect is exactly as if the second argument were
1255      * converted to a string by the method {@link String#valueOf(double)},
1256      * and the characters of that string were then
1257      * {@link #insert(int,String) inserted} into this character
1258      * sequence at the indicated offset.
1259      * <p>
1260      * The {@code offset} argument must be greater than or equal to
1261      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1262      * of this sequence.
1263      *
1264      * @param      offset   the offset.
1265      * @param      d        a {@code double}.
1266      * @return     a reference to this object.
1267      * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
1268      */
1269     public AbstractStringBuilder insert(int offset, double d) {
1270         return insert(offset, String.valueOf(d));
1271     }
1272 
1273     /**
1274      * Returns the index within this string of the first occurrence of the
1275      * specified substring. The integer returned is the smallest value
1276      * <i>k</i> such that:
1277      * <blockquote><pre>
1278      * this.toString().startsWith(str, <i>k</i>)
1279      * </pre></blockquote>
1280      * is {@code true}.
1281      *
1282      * @param   str   any string.
1283      * @return  if the string argument occurs as a substring within this
1284      *          object, then the index of the first character of the first
1285      *          such substring is returned; if it does not occur as a
1286      *          substring, {@code -1} is returned.
1287      */
1288     public int indexOf(String str) {
1289         return indexOf(str, 0);
1290     }
1291 
1292     /**
1293      * Returns the index within this string of the first occurrence of the
1294      * specified substring, starting at the specified index.  The integer
1295      * returned is the smallest value {@code k} for which:
1296      * <blockquote><pre>
1297      *     k >= Math.min(fromIndex, str.length()) &&
1298      *                   this.toString().startsWith(str, k)
1299      * </pre></blockquote>
1300      * If no such value of <i>k</i> exists, then -1 is returned.
1301      *
1302      * @param   str         the substring for which to search.
1303      * @param   fromIndex   the index from which to start the search.
1304      * @return  the index within this string of the first occurrence of the
1305      *          specified substring, starting at the specified index.
1306      */
1307     public int indexOf(String str, int fromIndex) {
1308         return String.indexOf(value, 0, count, str, fromIndex);
1309     }
1310 
1311     /**
1312      * Returns the index within this string of the rightmost occurrence
1313      * of the specified substring.  The rightmost empty string "" is
1314      * considered to occur at the index value {@code this.length()}.
1315      * The returned index is the largest value <i>k</i> such that
1316      * <blockquote><pre>
1317      * this.toString().startsWith(str, k)
1318      * </pre></blockquote>
1319      * is true.
1320      *
1321      * @param   str   the substring to search for.
1322      * @return  if the string argument occurs one or more times as a substring
1323      *          within this object, then the index of the first character of
1324      *          the last such substring is returned. If it does not occur as
1325      *          a substring, {@code -1} is returned.
1326      */
1327     public int lastIndexOf(String str) {
1328         return lastIndexOf(str, count);
1329     }
1330 
1331     /**
1332      * Returns the index within this string of the last occurrence of the
1333      * specified substring. The integer returned is the largest value <i>k</i>
1334      * such that:
1335      * <blockquote><pre>
1336      *     k <= Math.min(fromIndex, str.length()) &&
1337      *                   this.toString().startsWith(str, k)
1338      * </pre></blockquote>
1339      * If no such value of <i>k</i> exists, then -1 is returned.
1340      *
1341      * @param   str         the substring to search for.
1342      * @param   fromIndex   the index to start the search from.
1343      * @return  the index within this sequence of the last occurrence of the
1344      *          specified substring.
1345      */
1346     public int lastIndexOf(String str, int fromIndex) {
1347         return String.lastIndexOf(value, 0, count, str, fromIndex);
1348     }
1349 
1350     /**
1351      * Causes this character sequence to be replaced by the reverse of
1352      * the sequence. If there are any surrogate pairs included in the
1353      * sequence, these are treated as single characters for the
1354      * reverse operation. Thus, the order of the high-low surrogates
1355      * is never reversed.
1356      *
1357      * Let <i>n</i> be the character length of this character sequence
1358      * (not the length in {@code char} values) just prior to
1359      * execution of the {@code reverse} method. Then the
1360      * character at index <i>k</i> in the new character sequence is
1361      * equal to the character at index <i>n-k-1</i> in the old
1362      * character sequence.
1363      *
1364      * <p>Note that the reverse operation may result in producing
1365      * surrogate pairs that were unpaired low-surrogates and
1366      * high-surrogates before the operation. For example, reversing
1367      * "\u005CuDC00\u005CuD800" produces "\u005CuD800\u005CuDC00" which is
1368      * a valid surrogate pair.
1369      *
1370      * @return  a reference to this object.
1371      */
1372     public AbstractStringBuilder reverse() {
1373         boolean hasSurrogate = false;
1374         int n = count - 1;
1375         for (int j = (n-1) >> 1; j >= 0; --j) {
1376             char temp = value[j];
1377             char temp2 = value[n - j];
1378             if (!hasSurrogate) {
1379                 hasSurrogate = (temp >= Character.MIN_SURROGATE && temp <= Character.MAX_SURROGATE)
1380                     || (temp2 >= Character.MIN_SURROGATE && temp2 <= Character.MAX_SURROGATE);
1381             }
1382             value[j] = temp2;
1383             value[n - j] = temp;
1384         }
1385         if (hasSurrogate) {
1386             // Reverse back all valid surrogate pairs
1387             for (int i = 0; i < count - 1; i++) {
1388                 char c2 = value[i];
1389                 if (Character.isLowSurrogate(c2)) {
1390                     char c1 = value[i + 1];
1391                     if (Character.isHighSurrogate(c1)) {
1392                         value[i++] = c1;
1393                         value[i] = c2;
1394                     }
1395                 }
1396             }
1397         }
1398         return this;
1399     }
1400 
1401     /**
1402      * Returns a string representing the data in this sequence.
1403      * A new {@code String} object is allocated and initialized to
1404      * contain the character sequence currently represented by this
1405      * object. This {@code String} is then returned. Subsequent
1406      * changes to this sequence do not affect the contents of the
1407      * {@code String}.
1408      *
1409      * @return  a string representation of this sequence of characters.
1410      */
1411     @Override
1412     public abstract String toString();
1413 
1414     /**
1415      * Needed by {@code String} for the contentEquals method.
1416      */
1417     final char[] getValue() {
1418         return value;
1419     }
1420 
1421 }