jdk/src/share/classes/java/lang/AbstractStringBuilder.java
changeset 2 90ce3da70b43
child 1223 5c1037124466
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/lang/AbstractStringBuilder.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,1417 @@
+/*
+ * Copyright 2003-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package java.lang;
+
+import sun.misc.FloatingDecimal;
+import java.util.Arrays;
+
+/**
+ * A mutable sequence of characters.
+ * <p>
+ * Implements a modifiable string. At any point in time it contains some
+ * particular sequence of characters, but the length and content of the
+ * sequence can be changed through certain method calls.
+ *
+ * @author      Michael McCloskey
+ * @since       1.5
+ */
+abstract class AbstractStringBuilder implements Appendable, CharSequence {
+    /**
+     * The value is used for character storage.
+     */
+    char value[];
+
+    /**
+     * The count is the number of characters used.
+     */
+    int count;
+
+    /**
+     * This no-arg constructor is necessary for serialization of subclasses.
+     */
+    AbstractStringBuilder() {
+    }
+
+    /**
+     * Creates an AbstractStringBuilder of the specified capacity.
+     */
+    AbstractStringBuilder(int capacity) {
+        value = new char[capacity];
+    }
+
+    /**
+     * Returns the length (character count).
+     *
+     * @return  the length of the sequence of characters currently
+     *          represented by this object
+     */
+    public int length() {
+        return count;
+    }
+
+    /**
+     * Returns the current capacity. The capacity is the amount of storage
+     * available for newly inserted characters, beyond which an allocation
+     * will occur.
+     *
+     * @return  the current capacity
+     */
+    public int capacity() {
+        return value.length;
+    }
+
+    /**
+     * Ensures that the capacity is at least equal to the specified minimum.
+     * If the current capacity is less than the argument, then a new internal
+     * array is allocated with greater capacity. The new capacity is the
+     * larger of:
+     * <ul>
+     * <li>The <code>minimumCapacity</code> argument.
+     * <li>Twice the old capacity, plus <code>2</code>.
+     * </ul>
+     * If the <code>minimumCapacity</code> argument is nonpositive, this
+     * method takes no action and simply returns.
+     *
+     * @param   minimumCapacity   the minimum desired capacity.
+     */
+    public void ensureCapacity(int minimumCapacity) {
+        if (minimumCapacity > value.length) {
+            expandCapacity(minimumCapacity);
+        }
+    }
+
+    /**
+     * This implements the expansion semantics of ensureCapacity with no
+     * size check or synchronization.
+     */
+    void expandCapacity(int minimumCapacity) {
+        int newCapacity = (value.length + 1) * 2;
+        if (newCapacity < 0) {
+            newCapacity = Integer.MAX_VALUE;
+        } else if (minimumCapacity > newCapacity) {
+            newCapacity = minimumCapacity;
+        }
+        value = Arrays.copyOf(value, newCapacity);
+    }
+
+    /**
+     * Attempts to reduce storage used for the character sequence.
+     * If the buffer is larger than necessary to hold its current sequence of
+     * characters, then it may be resized to become more space efficient.
+     * Calling this method may, but is not required to, affect the value
+     * returned by a subsequent call to the {@link #capacity()} method.
+     */
+    public void trimToSize() {
+        if (count < value.length) {
+            value = Arrays.copyOf(value, count);
+        }
+    }
+
+    /**
+     * Sets the length of the character sequence.
+     * The sequence is changed to a new character sequence
+     * whose length is specified by the argument. For every nonnegative
+     * index <i>k</i> less than <code>newLength</code>, the character at
+     * index <i>k</i> in the new character sequence is the same as the
+     * character at index <i>k</i> in the old sequence if <i>k</i> is less
+     * than the length of the old character sequence; otherwise, it is the
+     * null character <code>'&#92;u0000'</code>.
+     *
+     * In other words, if the <code>newLength</code> argument is less than
+     * the current length, the length is changed to the specified length.
+     * <p>
+     * If the <code>newLength</code> argument is greater than or equal
+     * to the current length, sufficient null characters
+     * (<code>'&#92;u0000'</code>) are appended so that
+     * length becomes the <code>newLength</code> argument.
+     * <p>
+     * The <code>newLength</code> argument must be greater than or equal
+     * to <code>0</code>.
+     *
+     * @param      newLength   the new length
+     * @throws     IndexOutOfBoundsException  if the
+     *               <code>newLength</code> argument is negative.
+     */
+    public void setLength(int newLength) {
+        if (newLength < 0)
+            throw new StringIndexOutOfBoundsException(newLength);
+        if (newLength > value.length)
+            expandCapacity(newLength);
+
+        if (count < newLength) {
+            for (; count < newLength; count++)
+                value[count] = '\0';
+        } else {
+            count = newLength;
+        }
+    }
+
+    /**
+     * Returns the <code>char</code> value in this sequence at the specified index.
+     * The first <code>char</code> value is at index <code>0</code>, the next at index
+     * <code>1</code>, and so on, as in array indexing.
+     * <p>
+     * The index argument must be greater than or equal to
+     * <code>0</code>, and less than the length of this sequence.
+     *
+     * <p>If the <code>char</code> value specified by the index is a
+     * <a href="Character.html#unicode">surrogate</a>, the surrogate
+     * value is returned.
+     *
+     * @param      index   the index of the desired <code>char</code> value.
+     * @return     the <code>char</code> value at the specified index.
+     * @throws     IndexOutOfBoundsException  if <code>index</code> is
+     *             negative or greater than or equal to <code>length()</code>.
+     */
+    public char charAt(int index) {
+        if ((index < 0) || (index >= count))
+            throw new StringIndexOutOfBoundsException(index);
+        return value[index];
+    }
+
+    /**
+     * Returns the character (Unicode code point) at the specified
+     * index. The index refers to <code>char</code> values
+     * (Unicode code units) and ranges from <code>0</code> to
+     * {@link #length()}<code> - 1</code>.
+     *
+     * <p> If the <code>char</code> value specified at the given index
+     * is in the high-surrogate range, the following index is less
+     * than the length of this sequence, and the
+     * <code>char</code> value at the following index is in the
+     * low-surrogate range, then the supplementary code point
+     * corresponding to this surrogate pair is returned. Otherwise,
+     * the <code>char</code> value at the given index is returned.
+     *
+     * @param      index the index to the <code>char</code> values
+     * @return     the code point value of the character at the
+     *             <code>index</code>
+     * @exception  IndexOutOfBoundsException  if the <code>index</code>
+     *             argument is negative or not less than the length of this
+     *             sequence.
+     */
+    public int codePointAt(int index) {
+        if ((index < 0) || (index >= count)) {
+            throw new StringIndexOutOfBoundsException(index);
+        }
+        return Character.codePointAt(value, index);
+    }
+
+    /**
+     * Returns the character (Unicode code point) before the specified
+     * index. The index refers to <code>char</code> values
+     * (Unicode code units) and ranges from <code>1</code> to {@link
+     * #length()}.
+     *
+     * <p> If the <code>char</code> value at <code>(index - 1)</code>
+     * is in the low-surrogate range, <code>(index - 2)</code> is not
+     * negative, and the <code>char</code> value at <code>(index -
+     * 2)</code> is in the high-surrogate range, then the
+     * supplementary code point value of the surrogate pair is
+     * returned. If the <code>char</code> value at <code>index -
+     * 1</code> is an unpaired low-surrogate or a high-surrogate, the
+     * surrogate value is returned.
+     *
+     * @param     index the index following the code point that should be returned
+     * @return    the Unicode code point value before the given index.
+     * @exception IndexOutOfBoundsException if the <code>index</code>
+     *            argument is less than 1 or greater than the length
+     *            of this sequence.
+     */
+    public int codePointBefore(int index) {
+        int i = index - 1;
+        if ((i < 0) || (i >= count)) {
+            throw new StringIndexOutOfBoundsException(index);
+        }
+        return Character.codePointBefore(value, index);
+    }
+
+    /**
+     * Returns the number of Unicode code points in the specified text
+     * range of this sequence. The text range begins at the specified
+     * <code>beginIndex</code> and extends to the <code>char</code> at
+     * index <code>endIndex - 1</code>. Thus the length (in
+     * <code>char</code>s) of the text range is
+     * <code>endIndex-beginIndex</code>. Unpaired surrogates within
+     * this sequence count as one code point each.
+     *
+     * @param beginIndex the index to the first <code>char</code> of
+     * the text range.
+     * @param endIndex the index after the last <code>char</code> of
+     * the text range.
+     * @return the number of Unicode code points in the specified text
+     * range
+     * @exception IndexOutOfBoundsException if the
+     * <code>beginIndex</code> is negative, or <code>endIndex</code>
+     * is larger than the length of this sequence, or
+     * <code>beginIndex</code> is larger than <code>endIndex</code>.
+     */
+    public int codePointCount(int beginIndex, int endIndex) {
+        if (beginIndex < 0 || endIndex > count || beginIndex > endIndex) {
+            throw new IndexOutOfBoundsException();
+        }
+        return Character.codePointCountImpl(value, beginIndex, endIndex-beginIndex);
+    }
+
+    /**
+     * Returns the index within this sequence that is offset from the
+     * given <code>index</code> by <code>codePointOffset</code> code
+     * points. Unpaired surrogates within the text range given by
+     * <code>index</code> and <code>codePointOffset</code> count as
+     * one code point each.
+     *
+     * @param index the index to be offset
+     * @param codePointOffset the offset in code points
+     * @return the index within this sequence
+     * @exception IndexOutOfBoundsException if <code>index</code>
+     *   is negative or larger then the length of this sequence,
+     *   or if <code>codePointOffset</code> is positive and the subsequence
+     *   starting with <code>index</code> has fewer than
+     *   <code>codePointOffset</code> code points,
+     *   or if <code>codePointOffset</code> is negative and the subsequence
+     *   before <code>index</code> has fewer than the absolute value of
+     *   <code>codePointOffset</code> code points.
+     */
+    public int offsetByCodePoints(int index, int codePointOffset) {
+        if (index < 0 || index > count) {
+            throw new IndexOutOfBoundsException();
+        }
+        return Character.offsetByCodePointsImpl(value, 0, count,
+                                                index, codePointOffset);
+    }
+
+    /**
+     * Characters are copied from this sequence into the
+     * destination character array <code>dst</code>. The first character to
+     * be copied is at index <code>srcBegin</code>; the last character to
+     * be copied is at index <code>srcEnd-1</code>. The total number of
+     * characters to be copied is <code>srcEnd-srcBegin</code>. The
+     * characters are copied into the subarray of <code>dst</code> starting
+     * at index <code>dstBegin</code> and ending at index:
+     * <p><blockquote><pre>
+     * dstbegin + (srcEnd-srcBegin) - 1
+     * </pre></blockquote>
+     *
+     * @param      srcBegin   start copying at this offset.
+     * @param      srcEnd     stop copying at this offset.
+     * @param      dst        the array to copy the data into.
+     * @param      dstBegin   offset into <code>dst</code>.
+     * @throws     NullPointerException if <code>dst</code> is
+     *             <code>null</code>.
+     * @throws     IndexOutOfBoundsException  if any of the following is true:
+     *             <ul>
+     *             <li><code>srcBegin</code> is negative
+     *             <li><code>dstBegin</code> is negative
+     *             <li>the <code>srcBegin</code> argument is greater than
+     *             the <code>srcEnd</code> argument.
+     *             <li><code>srcEnd</code> is greater than
+     *             <code>this.length()</code>.
+     *             <li><code>dstBegin+srcEnd-srcBegin</code> is greater than
+     *             <code>dst.length</code>
+     *             </ul>
+     */
+    public void getChars(int srcBegin, int srcEnd, char dst[],
+                                      int dstBegin)
+    {
+        if (srcBegin < 0)
+            throw new StringIndexOutOfBoundsException(srcBegin);
+        if ((srcEnd < 0) || (srcEnd > count))
+            throw new StringIndexOutOfBoundsException(srcEnd);
+        if (srcBegin > srcEnd)
+            throw new StringIndexOutOfBoundsException("srcBegin > srcEnd");
+        System.arraycopy(value, srcBegin, dst, dstBegin, srcEnd - srcBegin);
+    }
+
+    /**
+     * The character at the specified index is set to <code>ch</code>. This
+     * sequence is altered to represent a new character sequence that is
+     * identical to the old character sequence, except that it contains the
+     * character <code>ch</code> at position <code>index</code>.
+     * <p>
+     * The index argument must be greater than or equal to
+     * <code>0</code>, and less than the length of this sequence.
+     *
+     * @param      index   the index of the character to modify.
+     * @param      ch      the new character.
+     * @throws     IndexOutOfBoundsException  if <code>index</code> is
+     *             negative or greater than or equal to <code>length()</code>.
+     */
+    public void setCharAt(int index, char ch) {
+        if ((index < 0) || (index >= count))
+            throw new StringIndexOutOfBoundsException(index);
+        value[index] = ch;
+    }
+
+    /**
+     * Appends the string representation of the <code>Object</code>
+     * argument.
+     * <p>
+     * The argument is converted to a string as if by the method
+     * <code>String.valueOf</code>, and the characters of that
+     * string are then appended to this sequence.
+     *
+     * @param   obj   an <code>Object</code>.
+     * @return  a reference to this object.
+     */
+    public AbstractStringBuilder append(Object obj) {
+        return append(String.valueOf(obj));
+    }
+
+    /**
+     * Appends the specified string to this character sequence.
+     * <p>
+     * The characters of the <code>String</code> argument are appended, in
+     * order, increasing the length of this sequence by the length of the
+     * argument. If <code>str</code> is <code>null</code>, then the four
+     * characters <code>"null"</code> are appended.
+     * <p>
+     * Let <i>n</i> be the length of this character sequence just prior to
+     * execution of the <code>append</code> method. Then the character at
+     * index <i>k</i> in the new character sequence is equal to the character
+     * at index <i>k</i> in the old character sequence, if <i>k</i> is less
+     * than <i>n</i>; otherwise, it is equal to the character at index
+     * <i>k-n</i> in the argument <code>str</code>.
+     *
+     * @param   str   a string.
+     * @return  a reference to this object.
+     */
+    public AbstractStringBuilder append(String str) {
+        if (str == null) str = "null";
+        int len = str.length();
+        if (len == 0) return this;
+        int newCount = count + len;
+        if (newCount > value.length)
+            expandCapacity(newCount);
+        str.getChars(0, len, value, count);
+        count = newCount;
+        return this;
+    }
+
+    // Documentation in subclasses because of synchro difference
+    public AbstractStringBuilder append(StringBuffer sb) {
+        if (sb == null)
+            return append("null");
+        int len = sb.length();
+        int newCount = count + len;
+        if (newCount > value.length)
+            expandCapacity(newCount);
+        sb.getChars(0, len, value, count);
+        count = newCount;
+        return this;
+    }
+
+    // Documentation in subclasses because of synchro difference
+    public AbstractStringBuilder append(CharSequence s) {
+        if (s == null)
+            s = "null";
+        if (s instanceof String)
+            return this.append((String)s);
+        if (s instanceof StringBuffer)
+            return this.append((StringBuffer)s);
+        return this.append(s, 0, s.length());
+    }
+
+    /**
+     * Appends a subsequence of the specified <code>CharSequence</code> to this
+     * sequence.
+     * <p>
+     * Characters of the argument <code>s</code>, starting at
+     * index <code>start</code>, are appended, in order, to the contents of
+     * this sequence up to the (exclusive) index <code>end</code>. The length
+     * of this sequence is increased by the value of <code>end - start</code>.
+     * <p>
+     * Let <i>n</i> be the length of this character sequence just prior to
+     * execution of the <code>append</code> method. Then the character at
+     * index <i>k</i> in this character sequence becomes equal to the
+     * character at index <i>k</i> in this sequence, if <i>k</i> is less than
+     * <i>n</i>; otherwise, it is equal to the character at index
+     * <i>k+start-n</i> in the argument <code>s</code>.
+     * <p>
+     * If <code>s</code> is <code>null</code>, then this method appends
+     * characters as if the s parameter was a sequence containing the four
+     * characters <code>"null"</code>.
+     *
+     * @param   s the sequence to append.
+     * @param   start   the starting index of the subsequence to be appended.
+     * @param   end     the end index of the subsequence to be appended.
+     * @return  a reference to this object.
+     * @throws     IndexOutOfBoundsException if
+     *                  <code>start</code> or <code>end</code> are negative, or
+     *             <code>start</code> is greater than <code>end</code> or
+     *             <code>end</code> is greater than <code>s.length()</code>
+     */
+    public AbstractStringBuilder append(CharSequence s, int start, int end) {
+        if (s == null)
+            s = "null";
+        if ((start < 0) || (end < 0) || (start > end) || (end > s.length()))
+            throw new IndexOutOfBoundsException(
+                "start " + start + ", end " + end + ", s.length() "
+                + s.length());
+        int len = end - start;
+        if (len == 0)
+            return this;
+        int newCount = count + len;
+        if (newCount > value.length)
+            expandCapacity(newCount);
+        for (int i=start; i<end; i++)
+            value[count++] = s.charAt(i);
+        count = newCount;
+        return this;
+    }
+
+    /**
+     * Appends the string representation of the <code>char</code> array
+     * argument to this sequence.
+     * <p>
+     * The characters of the array argument are appended, in order, to
+     * the contents of this sequence. The length of this sequence
+     * increases by the length of the argument.
+     * <p>
+     * The overall effect is exactly as if the argument were converted to
+     * a string by the method {@link String#valueOf(char[])} and the
+     * characters of that string were then {@link #append(String) appended}
+     * to this character sequence.
+     *
+     * @param   str   the characters to be appended.
+     * @return  a reference to this object.
+     */
+    public AbstractStringBuilder append(char str[]) {
+        int newCount = count + str.length;
+        if (newCount > value.length)
+            expandCapacity(newCount);
+        System.arraycopy(str, 0, value, count, str.length);
+        count = newCount;
+        return this;
+    }
+
+    /**
+     * Appends the string representation of a subarray of the
+     * <code>char</code> array argument to this sequence.
+     * <p>
+     * Characters of the <code>char</code> array <code>str</code>, starting at
+     * index <code>offset</code>, are appended, in order, to the contents
+     * of this sequence. The length of this sequence increases
+     * by the value of <code>len</code>.
+     * <p>
+     * The overall effect is exactly as if the arguments were converted to
+     * a string by the method {@link String#valueOf(char[],int,int)} and the
+     * characters of that string were then {@link #append(String) appended}
+     * to this character sequence.
+     *
+     * @param   str      the characters to be appended.
+     * @param   offset   the index of the first <code>char</code> to append.
+     * @param   len      the number of <code>char</code>s to append.
+     * @return  a reference to this object.
+     */
+    public AbstractStringBuilder append(char str[], int offset, int len) {
+        int newCount = count + len;
+        if (newCount > value.length)
+            expandCapacity(newCount);
+        System.arraycopy(str, offset, value, count, len);
+        count = newCount;
+        return this;
+    }
+
+    /**
+     * Appends the string representation of the <code>boolean</code>
+     * argument to the sequence.
+     * <p>
+     * The argument is converted to a string as if by the method
+     * <code>String.valueOf</code>, and the characters of that
+     * string are then appended to this sequence.
+     *
+     * @param   b   a <code>boolean</code>.
+     * @return  a reference to this object.
+     */
+    public AbstractStringBuilder append(boolean b) {
+        if (b) {
+            int newCount = count + 4;
+            if (newCount > value.length)
+                expandCapacity(newCount);
+            value[count++] = 't';
+            value[count++] = 'r';
+            value[count++] = 'u';
+            value[count++] = 'e';
+        } else {
+            int newCount = count + 5;
+            if (newCount > value.length)
+                expandCapacity(newCount);
+            value[count++] = 'f';
+            value[count++] = 'a';
+            value[count++] = 'l';
+            value[count++] = 's';
+            value[count++] = 'e';
+        }
+        return this;
+    }
+
+    /**
+     * Appends the string representation of the <code>char</code>
+     * argument to this sequence.
+     * <p>
+     * The argument is appended to the contents of this sequence.
+     * The length of this sequence increases by <code>1</code>.
+     * <p>
+     * The overall effect is exactly as if the argument were converted to
+     * a string by the method {@link String#valueOf(char)} and the character
+     * in that string were then {@link #append(String) appended} to this
+     * character sequence.
+     *
+     * @param   c   a <code>char</code>.
+     * @return  a reference to this object.
+     */
+    public AbstractStringBuilder append(char c) {
+        int newCount = count + 1;
+        if (newCount > value.length)
+            expandCapacity(newCount);
+        value[count++] = c;
+        return this;
+    }
+
+    /**
+     * Appends the string representation of the <code>int</code>
+     * argument to this sequence.
+     * <p>
+     * The argument is converted to a string as if by the method
+     * <code>String.valueOf</code>, and the characters of that
+     * string are then appended to this sequence.
+     *
+     * @param   i   an <code>int</code>.
+     * @return  a reference to this object.
+     */
+    public AbstractStringBuilder append(int i) {
+        if (i == Integer.MIN_VALUE) {
+            append("-2147483648");
+            return this;
+        }
+        int appendedLength = (i < 0) ? Integer.stringSize(-i) + 1
+                                     : Integer.stringSize(i);
+        int spaceNeeded = count + appendedLength;
+        if (spaceNeeded > value.length)
+            expandCapacity(spaceNeeded);
+        Integer.getChars(i, spaceNeeded, value);
+        count = spaceNeeded;
+        return this;
+    }
+
+    /**
+     * Appends the string representation of the <code>long</code>
+     * argument to this sequence.
+     * <p>
+     * The argument is converted to a string as if by the method
+     * <code>String.valueOf</code>, and the characters of that
+     * string are then appended to this sequence.
+     *
+     * @param   l   a <code>long</code>.
+     * @return  a reference to this object.
+     */
+    public AbstractStringBuilder append(long l) {
+        if (l == Long.MIN_VALUE) {
+            append("-9223372036854775808");
+            return this;
+        }
+        int appendedLength = (l < 0) ? Long.stringSize(-l) + 1
+                                     : Long.stringSize(l);
+        int spaceNeeded = count + appendedLength;
+        if (spaceNeeded > value.length)
+            expandCapacity(spaceNeeded);
+        Long.getChars(l, spaceNeeded, value);
+        count = spaceNeeded;
+        return this;
+    }
+
+    /**
+     * Appends the string representation of the <code>float</code>
+     * argument to this sequence.
+     * <p>
+     * The argument is converted to a string as if by the method
+     * <code>String.valueOf</code>, and the characters of that
+     * string are then appended to this string sequence.
+     *
+     * @param   f   a <code>float</code>.
+     * @return  a reference to this object.
+     */
+    public AbstractStringBuilder append(float f) {
+        new FloatingDecimal(f).appendTo(this);
+        return this;
+    }
+
+    /**
+     * Appends the string representation of the <code>double</code>
+     * argument to this sequence.
+     * <p>
+     * The argument is converted to a string as if by the method
+     * <code>String.valueOf</code>, and the characters of that
+     * string are then appended to this sequence.
+     *
+     * @param   d   a <code>double</code>.
+     * @return  a reference to this object.
+     */
+    public AbstractStringBuilder append(double d) {
+        new FloatingDecimal(d).appendTo(this);
+        return this;
+    }
+
+    /**
+     * Removes the characters in a substring of this sequence.
+     * The substring begins at the specified <code>start</code> and extends to
+     * the character at index <code>end - 1</code> or to the end of the
+     * sequence if no such character exists. If
+     * <code>start</code> is equal to <code>end</code>, no changes are made.
+     *
+     * @param      start  The beginning index, inclusive.
+     * @param      end    The ending index, exclusive.
+     * @return     This object.
+     * @throws     StringIndexOutOfBoundsException  if <code>start</code>
+     *             is negative, greater than <code>length()</code>, or
+     *             greater than <code>end</code>.
+     */
+    public AbstractStringBuilder delete(int start, int end) {
+        if (start < 0)
+            throw new StringIndexOutOfBoundsException(start);
+        if (end > count)
+            end = count;
+        if (start > end)
+            throw new StringIndexOutOfBoundsException();
+        int len = end - start;
+        if (len > 0) {
+            System.arraycopy(value, start+len, value, start, count-end);
+            count -= len;
+        }
+        return this;
+    }
+
+    /**
+     * Appends the string representation of the <code>codePoint</code>
+     * argument to this sequence.
+     *
+     * <p> The argument is appended to the contents of this sequence.
+     * The length of this sequence increases by
+     * {@link Character#charCount(int) Character.charCount(codePoint)}.
+     *
+     * <p> The overall effect is exactly as if the argument were
+     * converted to a <code>char</code> array by the method {@link
+     * Character#toChars(int)} and the character in that array were
+     * then {@link #append(char[]) appended} to this character
+     * sequence.
+     *
+     * @param   codePoint   a Unicode code point
+     * @return  a reference to this object.
+     * @exception IllegalArgumentException if the specified
+     * <code>codePoint</code> isn't a valid Unicode code point
+     */
+    public AbstractStringBuilder appendCodePoint(int codePoint) {
+        if (!Character.isValidCodePoint(codePoint)) {
+            throw new IllegalArgumentException();
+        }
+        int n = 1;
+        if (codePoint >= Character.MIN_SUPPLEMENTARY_CODE_POINT) {
+            n++;
+        }
+        int newCount = count + n;
+        if (newCount > value.length) {
+            expandCapacity(newCount);
+        }
+        if (n == 1) {
+            value[count++] = (char) codePoint;
+        } else {
+            Character.toSurrogates(codePoint, value, count);
+            count += n;
+        }
+        return this;
+    }
+
+    /**
+     * Removes the <code>char</code> at the specified position in this
+     * sequence. This sequence is shortened by one <code>char</code>.
+     *
+     * <p>Note: If the character at the given index is a supplementary
+     * character, this method does not remove the entire character. If
+     * correct handling of supplementary characters is required,
+     * determine the number of <code>char</code>s to remove by calling
+     * <code>Character.charCount(thisSequence.codePointAt(index))</code>,
+     * where <code>thisSequence</code> is this sequence.
+     *
+     * @param       index  Index of <code>char</code> to remove
+     * @return      This object.
+     * @throws      StringIndexOutOfBoundsException  if the <code>index</code>
+     *              is negative or greater than or equal to
+     *              <code>length()</code>.
+     */
+    public AbstractStringBuilder deleteCharAt(int index) {
+        if ((index < 0) || (index >= count))
+            throw new StringIndexOutOfBoundsException(index);
+        System.arraycopy(value, index+1, value, index, count-index-1);
+        count--;
+        return this;
+    }
+
+    /**
+     * Replaces the characters in a substring of this sequence
+     * with characters in the specified <code>String</code>. The substring
+     * begins at the specified <code>start</code> and extends to the character
+     * at index <code>end - 1</code> or to the end of the
+     * sequence if no such character exists. First the
+     * characters in the substring are removed and then the specified
+     * <code>String</code> is inserted at <code>start</code>. (This
+     * sequence will be lengthened to accommodate the
+     * specified String if necessary.)
+     *
+     * @param      start    The beginning index, inclusive.
+     * @param      end      The ending index, exclusive.
+     * @param      str   String that will replace previous contents.
+     * @return     This object.
+     * @throws     StringIndexOutOfBoundsException  if <code>start</code>
+     *             is negative, greater than <code>length()</code>, or
+     *             greater than <code>end</code>.
+     */
+    public AbstractStringBuilder replace(int start, int end, String str) {
+        if (start < 0)
+            throw new StringIndexOutOfBoundsException(start);
+        if (start > count)
+            throw new StringIndexOutOfBoundsException("start > length()");
+        if (start > end)
+            throw new StringIndexOutOfBoundsException("start > end");
+
+        if (end > count)
+            end = count;
+        int len = str.length();
+        int newCount = count + len - (end - start);
+        if (newCount > value.length)
+            expandCapacity(newCount);
+
+        System.arraycopy(value, end, value, start + len, count - end);
+        str.getChars(value, start);
+        count = newCount;
+        return this;
+    }
+
+    /**
+     * Returns a new <code>String</code> that contains a subsequence of
+     * characters currently contained in this character sequence. The
+     * substring begins at the specified index and extends to the end of
+     * this sequence.
+     *
+     * @param      start    The beginning index, inclusive.
+     * @return     The new string.
+     * @throws     StringIndexOutOfBoundsException  if <code>start</code> is
+     *             less than zero, or greater than the length of this object.
+     */
+    public String substring(int start) {
+        return substring(start, count);
+    }
+
+    /**
+     * Returns a new character sequence that is a subsequence of this sequence.
+     *
+     * <p> An invocation of this method of the form
+     *
+     * <blockquote><pre>
+     * sb.subSequence(begin,&nbsp;end)</pre></blockquote>
+     *
+     * behaves in exactly the same way as the invocation
+     *
+     * <blockquote><pre>
+     * sb.substring(begin,&nbsp;end)</pre></blockquote>
+     *
+     * This method is provided so that this class can
+     * implement the {@link CharSequence} interface. </p>
+     *
+     * @param      start   the start index, inclusive.
+     * @param      end     the end index, exclusive.
+     * @return     the specified subsequence.
+     *
+     * @throws  IndexOutOfBoundsException
+     *          if <tt>start</tt> or <tt>end</tt> are negative,
+     *          if <tt>end</tt> is greater than <tt>length()</tt>,
+     *          or if <tt>start</tt> is greater than <tt>end</tt>
+     * @spec JSR-51
+     */
+    public CharSequence subSequence(int start, int end) {
+        return substring(start, end);
+    }
+
+    /**
+     * Returns a new <code>String</code> that contains a subsequence of
+     * characters currently contained in this sequence. The
+     * substring begins at the specified <code>start</code> and
+     * extends to the character at index <code>end - 1</code>.
+     *
+     * @param      start    The beginning index, inclusive.
+     * @param      end      The ending index, exclusive.
+     * @return     The new string.
+     * @throws     StringIndexOutOfBoundsException  if <code>start</code>
+     *             or <code>end</code> are negative or greater than
+     *             <code>length()</code>, or <code>start</code> is
+     *             greater than <code>end</code>.
+     */
+    public String substring(int start, int end) {
+        if (start < 0)
+            throw new StringIndexOutOfBoundsException(start);
+        if (end > count)
+            throw new StringIndexOutOfBoundsException(end);
+        if (start > end)
+            throw new StringIndexOutOfBoundsException(end - start);
+        return new String(value, start, end - start);
+    }
+
+    /**
+     * Inserts the string representation of a subarray of the <code>str</code>
+     * array argument into this sequence. The subarray begins at the
+     * specified <code>offset</code> and extends <code>len</code> <code>char</code>s.
+     * The characters of the subarray are inserted into this sequence at
+     * the position indicated by <code>index</code>. The length of this
+     * sequence increases by <code>len</code> <code>char</code>s.
+     *
+     * @param      index    position at which to insert subarray.
+     * @param      str       A <code>char</code> array.
+     * @param      offset   the index of the first <code>char</code> in subarray to
+     *             be inserted.
+     * @param      len      the number of <code>char</code>s in the subarray to
+     *             be inserted.
+     * @return     This object
+     * @throws     StringIndexOutOfBoundsException  if <code>index</code>
+     *             is negative or greater than <code>length()</code>, or
+     *             <code>offset</code> or <code>len</code> are negative, or
+     *             <code>(offset+len)</code> is greater than
+     *             <code>str.length</code>.
+     */
+    public AbstractStringBuilder insert(int index, char str[], int offset,
+                                        int len)
+    {
+        if ((index < 0) || (index > length()))
+            throw new StringIndexOutOfBoundsException(index);
+        if ((offset < 0) || (len < 0) || (offset > str.length - len))
+            throw new StringIndexOutOfBoundsException(
+                "offset " + offset + ", len " + len + ", str.length "
+                + str.length);
+        int newCount = count + len;
+        if (newCount > value.length)
+            expandCapacity(newCount);
+        System.arraycopy(value, index, value, index + len, count - index);
+        System.arraycopy(str, offset, value, index, len);
+        count = newCount;
+        return this;
+    }
+
+    /**
+     * Inserts the string representation of the <code>Object</code>
+     * argument into this character sequence.
+     * <p>
+     * The second argument is converted to a string as if by the method
+     * <code>String.valueOf</code>, and the characters of that
+     * string are then inserted into this sequence at the indicated
+     * offset.
+     * <p>
+     * The offset argument must be greater than or equal to
+     * <code>0</code>, and less than or equal to the length of this
+     * sequence.
+     *
+     * @param      offset   the offset.
+     * @param      obj      an <code>Object</code>.
+     * @return     a reference to this object.
+     * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
+     */
+    public AbstractStringBuilder insert(int offset, Object obj) {
+        return insert(offset, String.valueOf(obj));
+    }
+
+    /**
+     * Inserts the string into this character sequence.
+     * <p>
+     * The characters of the <code>String</code> argument are inserted, in
+     * order, into this sequence at the indicated offset, moving up any
+     * characters originally above that position and increasing the length
+     * of this sequence by the length of the argument. If
+     * <code>str</code> is <code>null</code>, then the four characters
+     * <code>"null"</code> are inserted into this sequence.
+     * <p>
+     * The character at index <i>k</i> in the new character sequence is
+     * equal to:
+     * <ul>
+     * <li>the character at index <i>k</i> in the old character sequence, if
+     * <i>k</i> is less than <code>offset</code>
+     * <li>the character at index <i>k</i><code>-offset</code> in the
+     * argument <code>str</code>, if <i>k</i> is not less than
+     * <code>offset</code> but is less than <code>offset+str.length()</code>
+     * <li>the character at index <i>k</i><code>-str.length()</code> in the
+     * old character sequence, if <i>k</i> is not less than
+     * <code>offset+str.length()</code>
+     * </ul><p>
+     * The offset argument must be greater than or equal to
+     * <code>0</code>, and less than or equal to the length of this
+     * sequence.
+     *
+     * @param      offset   the offset.
+     * @param      str      a string.
+     * @return     a reference to this object.
+     * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
+     */
+    public AbstractStringBuilder insert(int offset, String str) {
+        if ((offset < 0) || (offset > length()))
+            throw new StringIndexOutOfBoundsException(offset);
+        if (str == null)
+            str = "null";
+        int len = str.length();
+        int newCount = count + len;
+        if (newCount > value.length)
+            expandCapacity(newCount);
+        System.arraycopy(value, offset, value, offset + len, count - offset);
+        str.getChars(value, offset);
+        count = newCount;
+        return this;
+    }
+
+    /**
+     * Inserts the string representation of the <code>char</code> array
+     * argument into this sequence.
+     * <p>
+     * The characters of the array argument are inserted into the
+     * contents of this sequence at the position indicated by
+     * <code>offset</code>. The length of this sequence increases by
+     * the length of the argument.
+     * <p>
+     * The overall effect is exactly as if the argument were converted to
+     * a string by the method {@link String#valueOf(char[])} and the
+     * characters of that string were then
+     * {@link #insert(int,String) inserted} into this
+     * character sequence at the position indicated by
+     * <code>offset</code>.
+     *
+     * @param      offset   the offset.
+     * @param      str      a character array.
+     * @return     a reference to this object.
+     * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
+     */
+    public AbstractStringBuilder insert(int offset, char str[]) {
+        if ((offset < 0) || (offset > length()))
+            throw new StringIndexOutOfBoundsException(offset);
+        int len = str.length;
+        int newCount = count + len;
+        if (newCount > value.length)
+            expandCapacity(newCount);
+        System.arraycopy(value, offset, value, offset + len, count - offset);
+        System.arraycopy(str, 0, value, offset, len);
+        count = newCount;
+        return this;
+    }
+
+    /**
+     * Inserts the specified <code>CharSequence</code> into this sequence.
+     * <p>
+     * The characters of the <code>CharSequence</code> argument are inserted,
+     * in order, into this sequence at the indicated offset, moving up
+     * any characters originally above that position and increasing the length
+     * of this sequence by the length of the argument s.
+     * <p>
+     * The result of this method is exactly the same as if it were an
+     * invocation of this object's insert(dstOffset, s, 0, s.length()) method.
+     *
+     * <p>If <code>s</code> is <code>null</code>, then the four characters
+     * <code>"null"</code> are inserted into this sequence.
+     *
+     * @param      dstOffset   the offset.
+     * @param      s the sequence to be inserted
+     * @return     a reference to this object.
+     * @throws     IndexOutOfBoundsException  if the offset is invalid.
+     */
+    public AbstractStringBuilder insert(int dstOffset, CharSequence s) {
+        if (s == null)
+            s = "null";
+        if (s instanceof String)
+            return this.insert(dstOffset, (String)s);
+        return this.insert(dstOffset, s, 0, s.length());
+    }
+
+    /**
+     * Inserts a subsequence of the specified <code>CharSequence</code> into
+     * this sequence.
+     * <p>
+     * The subsequence of the argument <code>s</code> specified by
+     * <code>start</code> and <code>end</code> are inserted,
+     * in order, into this sequence at the specified destination offset, moving
+     * up any characters originally above that position. The length of this
+     * sequence is increased by <code>end - start</code>.
+     * <p>
+     * The character at index <i>k</i> in this sequence becomes equal to:
+     * <ul>
+     * <li>the character at index <i>k</i> in this sequence, if
+     * <i>k</i> is less than <code>dstOffset</code>
+     * <li>the character at index <i>k</i><code>+start-dstOffset</code> in
+     * the argument <code>s</code>, if <i>k</i> is greater than or equal to
+     * <code>dstOffset</code> but is less than <code>dstOffset+end-start</code>
+     * <li>the character at index <i>k</i><code>-(end-start)</code> in this
+     * sequence, if <i>k</i> is greater than or equal to
+     * <code>dstOffset+end-start</code>
+     * </ul><p>
+     * The dstOffset argument must be greater than or equal to
+     * <code>0</code>, and less than or equal to the length of this
+     * sequence.
+     * <p>The start argument must be nonnegative, and not greater than
+     * <code>end</code>.
+     * <p>The end argument must be greater than or equal to
+     * <code>start</code>, and less than or equal to the length of s.
+     *
+     * <p>If <code>s</code> is <code>null</code>, then this method inserts
+     * characters as if the s parameter was a sequence containing the four
+     * characters <code>"null"</code>.
+     *
+     * @param      dstOffset   the offset in this sequence.
+     * @param      s       the sequence to be inserted.
+     * @param      start   the starting index of the subsequence to be inserted.
+     * @param      end     the end index of the subsequence to be inserted.
+     * @return     a reference to this object.
+     * @throws     IndexOutOfBoundsException  if <code>dstOffset</code>
+     *             is negative or greater than <code>this.length()</code>, or
+     *              <code>start</code> or <code>end</code> are negative, or
+     *              <code>start</code> is greater than <code>end</code> or
+     *              <code>end</code> is greater than <code>s.length()</code>
+     */
+     public AbstractStringBuilder insert(int dstOffset, CharSequence s,
+                                           int start, int end) {
+        if (s == null)
+            s = "null";
+        if ((dstOffset < 0) || (dstOffset > this.length()))
+            throw new IndexOutOfBoundsException("dstOffset "+dstOffset);
+        if ((start < 0) || (end < 0) || (start > end) || (end > s.length()))
+            throw new IndexOutOfBoundsException(
+                "start " + start + ", end " + end + ", s.length() "
+                + s.length());
+        int len = end - start;
+        if (len == 0)
+            return this;
+        int newCount = count + len;
+        if (newCount > value.length)
+            expandCapacity(newCount);
+        System.arraycopy(value, dstOffset, value, dstOffset + len,
+                         count - dstOffset);
+        for (int i=start; i<end; i++)
+            value[dstOffset++] = s.charAt(i);
+        count = newCount;
+        return this;
+    }
+
+    /**
+     * Inserts the string representation of the <code>boolean</code>
+     * argument into this sequence.
+     * <p>
+     * The second argument is converted to a string as if by the method
+     * <code>String.valueOf</code>, and the characters of that
+     * string are then inserted into this sequence at the indicated
+     * offset.
+     * <p>
+     * The offset argument must be greater than or equal to
+     * <code>0</code>, and less than or equal to the length of this
+     * sequence.
+     *
+     * @param      offset   the offset.
+     * @param      b        a <code>boolean</code>.
+     * @return     a reference to this object.
+     * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
+     */
+    public AbstractStringBuilder insert(int offset, boolean b) {
+        return insert(offset, String.valueOf(b));
+    }
+
+    /**
+     * Inserts the string representation of the <code>char</code>
+     * argument into this sequence.
+     * <p>
+     * The second argument is inserted into the contents of this sequence
+     * at the position indicated by <code>offset</code>. The length
+     * of this sequence increases by one.
+     * <p>
+     * The overall effect is exactly as if the argument were converted to
+     * a string by the method {@link String#valueOf(char)} and the character
+     * in that string were then {@link #insert(int, String) inserted} into
+     * this character sequence at the position indicated by
+     * <code>offset</code>.
+     * <p>
+     * The offset argument must be greater than or equal to
+     * <code>0</code>, and less than or equal to the length of this
+     * sequence.
+     *
+     * @param      offset   the offset.
+     * @param      c        a <code>char</code>.
+     * @return     a reference to this object.
+     * @throws     IndexOutOfBoundsException  if the offset is invalid.
+     */
+    public AbstractStringBuilder insert(int offset, char c) {
+        int newCount = count + 1;
+        if (newCount > value.length)
+            expandCapacity(newCount);
+        System.arraycopy(value, offset, value, offset + 1, count - offset);
+        value[offset] = c;
+        count = newCount;
+        return this;
+    }
+
+    /**
+     * Inserts the string representation of the second <code>int</code>
+     * argument into this sequence.
+     * <p>
+     * The second argument is converted to a string as if by the method
+     * <code>String.valueOf</code>, and the characters of that
+     * string are then inserted into this sequence at the indicated
+     * offset.
+     * <p>
+     * The offset argument must be greater than or equal to
+     * <code>0</code>, and less than or equal to the length of this
+     * sequence.
+     *
+     * @param      offset   the offset.
+     * @param      i        an <code>int</code>.
+     * @return     a reference to this object.
+     * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
+     */
+    public AbstractStringBuilder insert(int offset, int i) {
+        return insert(offset, String.valueOf(i));
+    }
+
+    /**
+     * Inserts the string representation of the <code>long</code>
+     * argument into this sequence.
+     * <p>
+     * The second argument is converted to a string as if by the method
+     * <code>String.valueOf</code>, and the characters of that
+     * string are then inserted into this sequence at the position
+     * indicated by <code>offset</code>.
+     * <p>
+     * The offset argument must be greater than or equal to
+     * <code>0</code>, and less than or equal to the length of this
+     * sequence.
+     *
+     * @param      offset   the offset.
+     * @param      l        a <code>long</code>.
+     * @return     a reference to this object.
+     * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
+     */
+    public AbstractStringBuilder insert(int offset, long l) {
+        return insert(offset, String.valueOf(l));
+    }
+
+    /**
+     * Inserts the string representation of the <code>float</code>
+     * argument into this sequence.
+     * <p>
+     * The second argument is converted to a string as if by the method
+     * <code>String.valueOf</code>, and the characters of that
+     * string are then inserted into this sequence at the indicated
+     * offset.
+     * <p>
+     * The offset argument must be greater than or equal to
+     * <code>0</code>, and less than or equal to the length of this
+     * sequence.
+     *
+     * @param      offset   the offset.
+     * @param      f        a <code>float</code>.
+     * @return     a reference to this object.
+     * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
+     */
+    public AbstractStringBuilder insert(int offset, float f) {
+        return insert(offset, String.valueOf(f));
+    }
+
+    /**
+     * Inserts the string representation of the <code>double</code>
+     * argument into this sequence.
+     * <p>
+     * The second argument is converted to a string as if by the method
+     * <code>String.valueOf</code>, and the characters of that
+     * string are then inserted into this sequence at the indicated
+     * offset.
+     * <p>
+     * The offset argument must be greater than or equal to
+     * <code>0</code>, and less than or equal to the length of this
+     * sequence.
+     *
+     * @param      offset   the offset.
+     * @param      d        a <code>double</code>.
+     * @return     a reference to this object.
+     * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
+     */
+    public AbstractStringBuilder insert(int offset, double d) {
+        return insert(offset, String.valueOf(d));
+    }
+
+    /**
+     * Returns the index within this string of the first occurrence of the
+     * specified substring. The integer returned is the smallest value
+     * <i>k</i> such that:
+     * <blockquote><pre>
+     * this.toString().startsWith(str, <i>k</i>)
+     * </pre></blockquote>
+     * is <code>true</code>.
+     *
+     * @param   str   any string.
+     * @return  if the string argument occurs as a substring within this
+     *          object, then the index of the first character of the first
+     *          such substring is returned; if it does not occur as a
+     *          substring, <code>-1</code> is returned.
+     * @throws  java.lang.NullPointerException if <code>str</code> is
+     *          <code>null</code>.
+     */
+    public int indexOf(String str) {
+        return indexOf(str, 0);
+    }
+
+    /**
+     * Returns the index within this string of the first occurrence of the
+     * specified substring, starting at the specified index.  The integer
+     * returned is the smallest value <tt>k</tt> for which:
+     * <blockquote><pre>
+     *     k >= Math.min(fromIndex, str.length()) &&
+     *                   this.toString().startsWith(str, k)
+     * </pre></blockquote>
+     * If no such value of <i>k</i> exists, then -1 is returned.
+     *
+     * @param   str         the substring for which to search.
+     * @param   fromIndex   the index from which to start the search.
+     * @return  the index within this string of the first occurrence of the
+     *          specified substring, starting at the specified index.
+     * @throws  java.lang.NullPointerException if <code>str</code> is
+     *            <code>null</code>.
+     */
+    public int indexOf(String str, int fromIndex) {
+        return String.indexOf(value, 0, count,
+                              str.toCharArray(), 0, str.length(), fromIndex);
+    }
+
+    /**
+     * Returns the index within this string of the rightmost occurrence
+     * of the specified substring.  The rightmost empty string "" is
+     * considered to occur at the index value <code>this.length()</code>.
+     * The returned index is the largest value <i>k</i> such that
+     * <blockquote><pre>
+     * this.toString().startsWith(str, k)
+     * </pre></blockquote>
+     * is true.
+     *
+     * @param   str   the substring to search for.
+     * @return  if the string argument occurs one or more times as a substring
+     *          within this object, then the index of the first character of
+     *          the last such substring is returned. If it does not occur as
+     *          a substring, <code>-1</code> is returned.
+     * @throws  java.lang.NullPointerException  if <code>str</code> is
+     *          <code>null</code>.
+     */
+    public int lastIndexOf(String str) {
+        return lastIndexOf(str, count);
+    }
+
+    /**
+     * Returns the index within this string of the last occurrence of the
+     * specified substring. The integer returned is the largest value <i>k</i>
+     * such that:
+     * <blockquote><pre>
+     *     k <= Math.min(fromIndex, str.length()) &&
+     *                   this.toString().startsWith(str, k)
+     * </pre></blockquote>
+     * If no such value of <i>k</i> exists, then -1 is returned.
+     *
+     * @param   str         the substring to search for.
+     * @param   fromIndex   the index to start the search from.
+     * @return  the index within this sequence of the last occurrence of the
+     *          specified substring.
+     * @throws  java.lang.NullPointerException if <code>str</code> is
+     *          <code>null</code>.
+     */
+    public int lastIndexOf(String str, int fromIndex) {
+        return String.lastIndexOf(value, 0, count,
+                              str.toCharArray(), 0, str.length(), fromIndex);
+    }
+
+    /**
+     * Causes this character sequence to be replaced by the reverse of
+     * the sequence. If there are any surrogate pairs included in the
+     * sequence, these are treated as single characters for the
+     * reverse operation. Thus, the order of the high-low surrogates
+     * is never reversed.
+     *
+     * Let <i>n</i> be the character length of this character sequence
+     * (not the length in <code>char</code> values) just prior to
+     * execution of the <code>reverse</code> method. Then the
+     * character at index <i>k</i> in the new character sequence is
+     * equal to the character at index <i>n-k-1</i> in the old
+     * character sequence.
+     *
+     * <p>Note that the reverse operation may result in producing
+     * surrogate pairs that were unpaired low-surrogates and
+     * high-surrogates before the operation. For example, reversing
+     * "&#92;uDC00&#92;uD800" produces "&#92;uD800&#92;uDC00" which is
+     * a valid surrogate pair.
+     *
+     * @return  a reference to this object.
+     */
+    public AbstractStringBuilder reverse() {
+        boolean hasSurrogate = false;
+        int n = count - 1;
+        for (int j = (n-1) >> 1; j >= 0; --j) {
+            char temp = value[j];
+            char temp2 = value[n - j];
+            if (!hasSurrogate) {
+                hasSurrogate = (temp >= Character.MIN_SURROGATE && temp <= Character.MAX_SURROGATE)
+                    || (temp2 >= Character.MIN_SURROGATE && temp2 <= Character.MAX_SURROGATE);
+            }
+            value[j] = temp2;
+            value[n - j] = temp;
+        }
+        if (hasSurrogate) {
+            // Reverse back all valid surrogate pairs
+            for (int i = 0; i < count - 1; i++) {
+                char c2 = value[i];
+                if (Character.isLowSurrogate(c2)) {
+                    char c1 = value[i + 1];
+                    if (Character.isHighSurrogate(c1)) {
+                        value[i++] = c1;
+                        value[i] = c2;
+                    }
+                }
+            }
+        }
+        return this;
+    }
+
+    /**
+     * Returns a string representing the data in this sequence.
+     * A new <code>String</code> object is allocated and initialized to
+     * contain the character sequence currently represented by this
+     * object. This <code>String</code> is then returned. Subsequent
+     * changes to this sequence do not affect the contents of the
+     * <code>String</code>.
+     *
+     * @return  a string representation of this sequence of characters.
+     */
+    public abstract String toString();
+
+    /**
+     * Needed by <tt>String</tt> for the contentEquals method.
+     */
+    final char[] getValue() {
+        return value;
+    }
+
+}