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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 *
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package java.lang;

import sun.misc.FloatingDecimal;
import java.util.Arrays;

A mutable sequence of characters.

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/**
 * 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.
/**
     * The value is used for character storage.
     */
    char value[];

    
The count is the number of characters used.
/**
     * The count is the number of characters used.
     */
    int count;

    
This no-arg constructor is necessary for serialization of subclasses.
/**
     * This no-arg constructor is necessary for serialization of subclasses.
     */
    AbstractStringBuilder() {
    }

    
Creates an AbstractStringBuilder of the specified capacity.
/**
     * Creates an AbstractStringBuilder of the specified capacity.
     */
    AbstractStringBuilder(int capacity) {
        value = new char[capacity];
    }

    
Returns the length (character count).
Returns:
 the length of the sequence of characters currently
         represented by this object/**
     * 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.
Returns:
 the current capacity/**
     * 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:

The minimumCapacity argument.
Twice the old capacity, plus 2.

If the minimumCapacity argument is nonpositive, this
method takes no action and simply returns.
Params:
minimumCapacity –   the minimum desired capacity./**
     * 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.
/**
     * 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 capacity() method. /**
     * 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 k less than newLength, the character at
index k in the new character sequence is the same as the
character at index k in the old sequence if k is less
than the length of the old character sequence; otherwise, it is the
null character '\u0000'.
In other words, if the newLength argument is less than
the current length, the length is changed to the specified length.

If the newLength argument is greater than or equal
to the current length, sufficient null characters
('\u0000') are appended so that
length becomes the newLength argument.

The newLength argument must be greater than or equal
to 0.
Params:
newLength –   the new length
Throws:
IndexOutOfBoundsException –  if the
              newLength argument is negative./**
     * 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 char value in this sequence at the specified index.
The first char value is at index 0, the next at index
1, and so on, as in array indexing.

The index argument must be greater than or equal to
0, and less than the length of this sequence.
If the char value specified by the index is a
surrogate, the surrogate
value is returned.
Params:
index –   the index of the desired char value.
Throws:
IndexOutOfBoundsException –  if index is
            negative or greater than or equal to length().
Returns:
    the char value at the specified index./**
     * 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 char values
(Unicode code units) and ranges from 0 to length() - 1.
 If the char 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
char 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 char value at the given index is returned.
Params:
index – the index to the char values
Throws:
IndexOutOfBoundsException –  if the index
            argument is negative or not less than the length of this
            sequence.
Returns:
    the code point value of the character at the
            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 char values
(Unicode code units) and ranges from 1 to length(). 
 If the char value at (index - 1)
is in the low-surrogate range, (index - 2) is not
negative, and the char value at (index -
2) is in the high-surrogate range, then the
supplementary code point value of the surrogate pair is
returned. If the char value at index -
1 is an unpaired low-surrogate or a high-surrogate, the
surrogate value is returned.
Params:
index – the index following the code point that should be returned
Throws:
IndexOutOfBoundsException – if the index
           argument is less than 1 or greater than the length
           of this sequence.
Returns:
   the Unicode code point value before the given 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
beginIndex and extends to the char at
index endIndex - 1. Thus the length (in
chars) of the text range is
endIndex-beginIndex. Unpaired surrogates within
this sequence count as one code point each.
Params:
beginIndex – the index to the first char of
the text range.
endIndex – the index after the last char of
the text range.
Throws:
IndexOutOfBoundsException – if the
beginIndex is negative, or endIndex
is larger than the length of this sequence, or
beginIndex is larger than endIndex.
Returns:
the number of Unicode code points in the specified text
range/**
     * 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 index by codePointOffset code
points. Unpaired surrogates within the text range given by
index and codePointOffset count as
one code point each.
Params:
index – the index to be offset
codePointOffset – the offset in code points
Throws:
IndexOutOfBoundsException – if index
  is negative or larger then the length of this sequence,
  or if codePointOffset is positive and the subsequence
  starting with index has fewer than
  codePointOffset code points,
  or if codePointOffset is negative and the subsequence
  before index has fewer than the absolute value of
  codePointOffset code points.
Returns:
the index within this sequence/**
     * 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 dst. The first character to
be copied is at index srcBegin; the last character to
be copied is at index srcEnd-1. The total number of
characters to be copied is srcEnd-srcBegin. The
characters are copied into the subarray of dst starting
at index dstBegin and ending at index:
dstbegin + (srcEnd-srcBegin) - 1

Params:
srcBegin –   start copying at this offset.
srcEnd –     stop copying at this offset.
dst –        the array to copy the data into.
dstBegin –   offset into dst.
Throws:
NullPointerException – if dst is
            null.
IndexOutOfBoundsException –  if any of the following is true:
            

            
srcBegin is negative
            
dstBegin is negative
            
the srcBegin argument is greater than
            the srcEnd argument.
            
srcEnd is greater than
            this.length().
            
dstBegin+srcEnd-srcBegin is greater than
            dst.length
            /**
     * 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 ch. This
sequence is altered to represent a new character sequence that is
identical to the old character sequence, except that it contains the
character ch at position index.

The index argument must be greater than or equal to
0, and less than the length of this sequence.
Params:
index –   the index of the character to modify.
ch –      the new character.
Throws:
IndexOutOfBoundsException –  if index is
            negative or greater than or equal to length()./**
     * 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 Object
argument.

The argument is converted to a string as if by the method
String.valueOf, and the characters of that
string are then appended to this sequence.
Params:
obj –   an Object.
Returns:
 a reference to this object./**
     * 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.

The characters of the String argument are appended, in
order, increasing the length of this sequence by the length of the
argument. If str is null, then the four
characters "null" are appended.

Let n be the length of this character sequence just prior to
execution of the append method. Then the character at
index k in the new character sequence is equal to the character
at index k in the old character sequence, if k is less
than n; otherwise, it is equal to the character at index
k-n in the argument str.
Params:
str –   a string.
Returns:
 a reference to this object./**
     * 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 CharSequence to this
sequence.

Characters of the argument s, starting at
index start, are appended, in order, to the contents of
this sequence up to the (exclusive) index end. The length
of this sequence is increased by the value of end - start.

Let n be the length of this character sequence just prior to
execution of the append method. Then the character at
index k in this character sequence becomes equal to the
character at index k in this sequence, if k is less than
n; otherwise, it is equal to the character at index
k+start-n in the argument s.

If s is null, then this method appends
characters as if the s parameter was a sequence containing the four
characters "null".
Params:
s – the sequence to append.
start –   the starting index of the subsequence to be appended.
end –     the end index of the subsequence to be appended.
Throws:
IndexOutOfBoundsException – if
                 start or end are negative, or
            start is greater than end or
            end is greater than s.length()
Returns:
 a reference to this object./**
     * 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 char array
argument to this sequence.

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.
 The overall effect is exactly as if the argument were converted to a string by the method String.valueOf(char[]) and the characters of that string were then appended to this character sequence. 
Params:
str –   the characters to be appended.
Returns:
 a reference to this object./**
     * 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
char array argument to this sequence.

Characters of the char array str, starting at
index offset, are appended, in order, to the contents
of this sequence. The length of this sequence increases
by the value of len.
 The overall effect is exactly as if the arguments were converted to a string by the method String.valueOf(char[], int, int) and the characters of that string were then appended to this character sequence. 
Params:
str –      the characters to be appended.
offset –   the index of the first char to append.
len –      the number of chars to append.
Returns:
 a reference to this object./**
     * 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 boolean
argument to the sequence.

The argument is converted to a string as if by the method
String.valueOf, and the characters of that
string are then appended to this sequence.
Params:
b –   a boolean.
Returns:
 a reference to this object./**
     * 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 char
argument to this sequence.

The argument is appended to the contents of this sequence.
The length of this sequence increases by 1.
 The overall effect is exactly as if the argument were converted to a string by the method String.valueOf(char) and the character in that string were then appended to this character sequence. 
Params:
c –   a char.
Returns:
 a reference to this object./**
     * 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 int
argument to this sequence.

The argument is converted to a string as if by the method
String.valueOf, and the characters of that
string are then appended to this sequence.
Params:
i –   an int.
Returns:
 a reference to this object./**
     * 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 long
argument to this sequence.

The argument is converted to a string as if by the method
String.valueOf, and the characters of that
string are then appended to this sequence.
Params:
l –   a long.
Returns:
 a reference to this object./**
     * 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 float
argument to this sequence.

The argument is converted to a string as if by the method
String.valueOf, and the characters of that
string are then appended to this string sequence.
Params:
f –   a float.
Returns:
 a reference to this object./**
     * 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 double
argument to this sequence.

The argument is converted to a string as if by the method
String.valueOf, and the characters of that
string are then appended to this sequence.
Params:
d –   a double.
Returns:
 a reference to this object./**
     * 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 start and extends to
the character at index end - 1 or to the end of the
sequence if no such character exists. If
start is equal to end, no changes are made.
Params:
start –  The beginning index, inclusive.
end –    The ending index, exclusive.
Throws:
StringIndexOutOfBoundsException –  if start
            is negative, greater than length(), or
            greater than end.
Returns:
    This object./**
     * 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 codePoint
argument to this sequence.
 The argument is appended to the contents of this sequence. The length of this sequence increases by Character.charCount(codePoint). 
 The overall effect is exactly as if the argument were
converted to a char array by the method Character.toChars(int) and the character in that array were then appended to this character sequence. 
Params:
codePoint –   a Unicode code point
Throws:
IllegalArgumentException – if the specified
codePoint isn't a valid Unicode code point
Returns:
 a reference to this object./**
     * 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 char at the specified position in this
sequence. This sequence is shortened by one char.
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 chars to remove by calling
Character.charCount(thisSequence.codePointAt(index)),
where thisSequence is this sequence.
Params:
index –  Index of char to remove
Throws:
StringIndexOutOfBoundsException –  if the index
             is negative or greater than or equal to
             length().
Returns:
     This object./**
     * 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 String. The substring
begins at the specified start and extends to the character
at index end - 1 or to the end of the
sequence if no such character exists. First the
characters in the substring are removed and then the specified
String is inserted at start. (This
sequence will be lengthened to accommodate the
specified String if necessary.)
Params:
start –    The beginning index, inclusive.
end –      The ending index, exclusive.
str –   String that will replace previous contents.
Throws:
StringIndexOutOfBoundsException –  if start
            is negative, greater than length(), or
            greater than end.
Returns:
    This object./**
     * 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 String 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.
Params:
start –    The beginning index, inclusive.
Throws:
StringIndexOutOfBoundsException –  if start is
            less than zero, or greater than the length of this object.
Returns:
    The new string./**
     * 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.
 An invocation of this method of the form
sb.subSequence(begin, end)
behaves in exactly the same way as the invocation
sb.substring(begin, end)
 This method is provided so that this class can implement the CharSequence interface. 

Params:
start –   the start index, inclusive.
end –     the end index, exclusive.
Throws:
IndexOutOfBoundsException – 
         if start or end are negative,
         if end is greater than length(),
         or if start is greater than end
Returns:
    the specified subsequence.
@spec
JSR-51/**
     * 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 String that contains a subsequence of
characters currently contained in this sequence. The
substring begins at the specified start and
extends to the character at index end - 1.
Params:
start –    The beginning index, inclusive.
end –      The ending index, exclusive.
Throws:
StringIndexOutOfBoundsException –  if start
            or end are negative or greater than
            length(), or start is
            greater than end.
Returns:
    The new string./**
     * 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 str
array argument into this sequence. The subarray begins at the
specified offset and extends len chars.
The characters of the subarray are inserted into this sequence at
the position indicated by index. The length of this
sequence increases by len chars.
Params:
index –    position at which to insert subarray.
str –       A char array.
offset –   the index of the first char in subarray to
            be inserted.
len –      the number of chars in the subarray to
            be inserted.
Throws:
StringIndexOutOfBoundsException –  if index
            is negative or greater than length(), or
            offset or len are negative, or
            (offset+len) is greater than
            str.length.
Returns:
    This object/**
     * 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 Object
argument into this character sequence.

The second argument is converted to a string as if by the method
String.valueOf, and the characters of that
string are then inserted into this sequence at the indicated
offset.

The offset argument must be greater than or equal to
0, and less than or equal to the length of this
sequence.
Params:
offset –   the offset.
obj –      an Object.
Throws:
StringIndexOutOfBoundsException –  if the offset is invalid.
Returns:
    a reference to this object./**
     * 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.

The characters of the String 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
str is null, then the four characters
"null" are inserted into this sequence.

The character at index k in the new character sequence is
equal to:

the character at index k in the old character sequence, if
k is less than offset
the character at index k-offset in the
argument str, if k is not less than
offset but is less than offset+str.length()
the character at index k-str.length() in the
old character sequence, if k is not less than
offset+str.length()

The offset argument must be greater than or equal to
0, and less than or equal to the length of this
sequence.
Params:
offset –   the offset.
str –      a string.
Throws:
StringIndexOutOfBoundsException –  if the offset is invalid.
Returns:
    a reference to this object./**
     * 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 char array
argument into this sequence.

The characters of the array argument are inserted into the
contents of this sequence at the position indicated by
offset. The length of this sequence increases by
the length of the argument.
 The overall effect is exactly as if the argument were converted to a string by the method String.valueOf(char[]) and the characters of that string were then inserted into this character sequence at the position indicated by offset.
Params:
offset –   the offset.
str –      a character array.
Throws:
StringIndexOutOfBoundsException –  if the offset is invalid.
Returns:
    a reference to this object./**
     * 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 CharSequence into this sequence.

The characters of the CharSequence 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.

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.
If s is null, then the four characters
"null" are inserted into this sequence.
Params:
dstOffset –   the offset.
s – the sequence to be inserted
Throws:
IndexOutOfBoundsException –  if the offset is invalid.
Returns:
    a reference to this object./**
     * 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 CharSequence into
this sequence.

The subsequence of the argument s specified by
start and end 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 end - start.

The character at index k in this sequence becomes equal to:

the character at index k in this sequence, if
k is less than dstOffset
the character at index k+start-dstOffset in
the argument s, if k is greater than or equal to
dstOffset but is less than dstOffset+end-start
the character at index k-(end-start) in this
sequence, if k is greater than or equal to
dstOffset+end-start

The dstOffset argument must be greater than or equal to
0, and less than or equal to the length of this
sequence.
The start argument must be nonnegative, and not greater than
end.
The end argument must be greater than or equal to
start, and less than or equal to the length of s.
If s is null, then this method inserts
characters as if the s parameter was a sequence containing the four
characters "null".
Params:
dstOffset –   the offset in this sequence.
s –       the sequence to be inserted.
start –   the starting index of the subsequence to be inserted.
end –     the end index of the subsequence to be inserted.
Throws:
IndexOutOfBoundsException –  if dstOffset
            is negative or greater than this.length(), or
             start or end are negative, or
             start is greater than end or
             end is greater than s.length()
Returns:
    a reference to this object./**
     * 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 boolean
argument into this sequence.

The second argument is converted to a string as if by the method
String.valueOf, and the characters of that
string are then inserted into this sequence at the indicated
offset.

The offset argument must be greater than or equal to
0, and less than or equal to the length of this
sequence.
Params:
offset –   the offset.
b –        a boolean.
Throws:
StringIndexOutOfBoundsException –  if the offset is invalid.
Returns:
    a reference to this object./**
     * 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 char
argument into this sequence.

The second argument is inserted into the contents of this sequence
at the position indicated by offset. The length
of this sequence increases by one.
 The overall effect is exactly as if the argument were converted to a string by the method String.valueOf(char) and the character in that string were then inserted into this character sequence at the position indicated by offset.

The offset argument must be greater than or equal to
0, and less than or equal to the length of this
sequence.
Params:
offset –   the offset.
c –        a char.
Throws:
IndexOutOfBoundsException –  if the offset is invalid.
Returns:
    a reference to this object./**
     * 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 int
argument into this sequence.

The second argument is converted to a string as if by the method
String.valueOf, and the characters of that
string are then inserted into this sequence at the indicated
offset.

The offset argument must be greater than or equal to
0, and less than or equal to the length of this
sequence.
Params:
offset –   the offset.
i –        an int.
Throws:
StringIndexOutOfBoundsException –  if the offset is invalid.
Returns:
    a reference to this object./**
     * 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 long
argument into this sequence.

The second argument is converted to a string as if by the method
String.valueOf, and the characters of that
string are then inserted into this sequence at the position
indicated by offset.

The offset argument must be greater than or equal to
0, and less than or equal to the length of this
sequence.
Params:
offset –   the offset.
l –        a long.
Throws:
StringIndexOutOfBoundsException –  if the offset is invalid.
Returns:
    a reference to this object./**
     * 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 float
argument into this sequence.

The second argument is converted to a string as if by the method
String.valueOf, and the characters of that
string are then inserted into this sequence at the indicated
offset.

The offset argument must be greater than or equal to
0, and less than or equal to the length of this
sequence.
Params:
offset –   the offset.
f –        a float.
Throws:
StringIndexOutOfBoundsException –  if the offset is invalid.
Returns:
    a reference to this object./**
     * 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 double
argument into this sequence.

The second argument is converted to a string as if by the method
String.valueOf, and the characters of that
string are then inserted into this sequence at the indicated
offset.

The offset argument must be greater than or equal to
0, and less than or equal to the length of this
sequence.
Params:
offset –   the offset.
d –        a double.
Throws:
StringIndexOutOfBoundsException –  if the offset is invalid.
Returns:
    a reference to this object./**
     * 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
k such that:
this.toString().startsWith(str, k)

is true.
Params:
str –   any string.
Throws:
NullPointerException – if str is
         null.
Returns:
 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, -1 is returned./**
     * 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 k for which:
    k >= Math.min(fromIndex, str.length()) &&
                  this.toString().startsWith(str, k)

If no such value of k exists, then -1 is returned.
Params:
str –         the substring for which to search.
fromIndex –   the index from which to start the search.
Throws:
NullPointerException – if str is
           null.
Returns:
 the index within this string of the first occurrence of the
         specified substring, starting at the specified index./**
     * 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 this.length().
The returned index is the largest value k such that
this.toString().startsWith(str, k)

is true.
Params:
str –   the substring to search for.
Throws:
NullPointerException –  if str is
         null.
Returns:
 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, -1 is returned./**
     * 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 k
such that:
    k <= Math.min(fromIndex, str.length()) &&
                  this.toString().startsWith(str, k)

If no such value of k exists, then -1 is returned.
Params:
str –         the substring to search for.
fromIndex –   the index to start the search from.
Throws:
NullPointerException – if str is
         null.
Returns:
 the index within this sequence of the last occurrence of the
         specified substring./**
     * 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 n be the character length of this character sequence
(not the length in char values) just prior to
execution of the reverse method. Then the
character at index k in the new character sequence is
equal to the character at index n-k-1 in the old
character sequence.
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
"\uDC00\uD800" produces "\uD800\uDC00" which is
a valid surrogate pair.
Returns:
 a reference to this object./**
     * 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 String object is allocated and initialized to
contain the character sequence currently represented by this
object. This String is then returned. Subsequent
changes to this sequence do not affect the contents of the
String.
Returns:
 a string representation of this sequence of characters./**
     * 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 String for the contentEquals method.
/**
     * Needed by <tt>String</tt> for the contentEquals method.
     */
    final char[] getValue() {
        return value;
    }

}