stringbuffer.java

This is a resource based on j2me embedded,if you dont understand,you can connection with me .

     */
    public synchronized StringBuffer insert(int offset, char str[]) {
	if ((offset < 0) || (offset > count)) {
	    throw new StringIndexOutOfBoundsException();
	}
	int len = str.length;
	int newcount = count + len;
	if (newcount > value.length)
	    expandCapacity(newcount);
	else if (shared)
	    copy();

	if(count != offset) { /* IAI - 17 */
            CVM.copyCharArray(value, offset, value, offset + len, count - offset);
        }

	if(len != 0) { /* IAI - 17 */
            CVM.copyCharArray(str, 0, value, offset, len);
        }
	count = newcount;
	return this;
    }

    /**
     * Inserts the string representation of the <code>boolean</code> 
     * argument into this string buffer. 
     * <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 string buffer 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 
     * string buffer. 
     *
     * @param      offset   the offset.
     * @param      b        a <code>boolean</code>.
     * @return     a reference to this <code>StringBuffer</code> object.
     * @exception  StringIndexOutOfBoundsException  if the offset is invalid.
     * @see        java.lang.String#valueOf(boolean)
     * @see        java.lang.StringBuffer#insert(int, java.lang.String)
     * @see        java.lang.StringBuffer#length()
     */
    public StringBuffer insert(int offset, boolean b) {
	return insert(offset, String.valueOf(b));
    }

    /**
     * Inserts the string representation of the <code>char</code> 
     * argument into this string buffer. 
     * <p>
     * The second argument is inserted into the contents of this string 
     * buffer at the position indicated by <code>offset</code>. The length 
     * of this string buffer 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 <code>StringBuffer</code> object 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 
     * string buffer. 
     *
     * @param      offset   the offset.
     * @param      c        a <code>char</code>.
     * @return     a reference to this <code>StringBuffer</code> object.
     * @exception  IndexOutOfBoundsException  if the offset is invalid.
     * @see        java.lang.StringBuffer#length()
     */
    public synchronized StringBuffer insert(int offset, char c) {
	int newcount = count + 1;
	if (newcount > value.length)
	    expandCapacity(newcount);
	else if (shared)
	    copy();
/* IAI - 15 */
        if ((offset < 0) || (offset > count)) {
             throw new StringIndexOutOfBoundsException(offset);
        }

	if(count != offset) { 	/* IAI - 17 */
	    CVM.copyCharArray(value, offset, value, offset + 1, count - offset);
        }
/* IAI - 15 */

	value[offset] = c;
	count = newcount;
	return this;
    }

    /**
     * Inserts the string representation of the second <code>int</code> 
     * argument into this string buffer. 
     * <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 string buffer 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 
     * string buffer. 
     *
     * @param      offset   the offset.
     * @param      i        an <code>int</code>.
     * @return     a reference to this <code>StringBuffer</code> object.
     * @exception  StringIndexOutOfBoundsException  if the offset is invalid.
     * @see        java.lang.String#valueOf(int)
     * @see        java.lang.StringBuffer#insert(int, java.lang.String)
     * @see        java.lang.StringBuffer#length()
     */
    public StringBuffer insert(int offset, int i) {
	return insert(offset, String.valueOf(i));
    }

    /**
     * Inserts the string representation of the <code>long</code> 
     * argument into this string buffer. 
     * <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 string buffer 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 
     * string buffer. 
     *
     * @param      offset   the offset.
     * @param      l        a <code>long</code>.
     * @return     a reference to this <code>StringBuffer</code> object.
     * @exception  StringIndexOutOfBoundsException  if the offset is invalid.
     * @see        java.lang.String#valueOf(long)
     * @see        java.lang.StringBuffer#insert(int, java.lang.String)
     * @see        java.lang.StringBuffer#length()
     */
    public StringBuffer insert(int offset, long l) {
	return insert(offset, String.valueOf(l));
    }

    /**
     * Inserts the string representation of the <code>float</code> 
     * argument into this string buffer. 
     * <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 string buffer 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 
     * string buffer. 
     *
     * @param      offset   the offset.
     * @param      f        a <code>float</code>.
     * @return     a reference to this <code>StringBuffer</code> object.
     * @exception  StringIndexOutOfBoundsException  if the offset is invalid.
     * @see        java.lang.String#valueOf(float)
     * @see        java.lang.StringBuffer#insert(int, java.lang.String)
     * @see        java.lang.StringBuffer#length()
     */
    public StringBuffer insert(int offset, float f) {
	return insert(offset, String.valueOf(f));
    }

    /**
     * Inserts the string representation of the <code>double</code> 
     * argument into this string buffer. 
     * <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 string buffer 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 
     * string buffer. 
     *
     * @param      offset   the offset.
     * @param      d        a <code>double</code>.
     * @return     a reference to this <code>StringBuffer</code> object.
     * @exception  StringIndexOutOfBoundsException  if the offset is invalid.
     * @see        java.lang.String#valueOf(double)
     * @see        java.lang.StringBuffer#insert(int, java.lang.String)
     * @see        java.lang.StringBuffer#length()
     */
    public StringBuffer 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.
     * @exception java.lang.NullPointerException if <code>str</code> is 
     *          <code>null</code>.
     * @since   1.4
     */
    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.
     * @exception java.lang.NullPointerException if <code>str</code> is
     *            <code>null</code>.
     * @since   1.4
     */
    public synchronized 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.
     * @exception java.lang.NullPointerException  if <code>str</code> is 
     *          <code>null</code>.
     * @since   1.4
     */
    public synchronized 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 string of the last occurrence of the
     *          specified substring.
     * @exception java.lang.NullPointerException if <code>str</code> is 
     *          <code>null</code>.
     * @since   1.4
     */
    public synchronized int lastIndexOf(String str, int fromIndex) {
        return String.lastIndexOf(value, 0, count,
                              str.toCharArray(), 0, str.length(), fromIndex);
    }

    /**
     * The character sequence contained in this string buffer is 
     * replaced by the reverse of the sequence. 
     * <p>
     * Let <i>n</i> be the length of the old character sequence, the one 
     * contained in the string buffer 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.
     *
     * @return  a reference to this <code>StringBuffer</code> object.
     * @since   JDK1.0.2
     */
    public synchronized StringBuffer reverse() {
	if (shared) copy();
	int n = count - 1;
	for (int j = (n-1) >> 1; j >= 0; --j) {
	    char temp = value[j];
	    value[j] = value[n - j];
	    value[n - j] = temp;
	}
	return this;
    }

    /**
     * Converts to a string representing the data in this string buffer.
     * A new <code>String</code> object is allocated and initialized to 
     * contain the character sequence currently represented by this 
     * string buffer. This <code>String</code> is then returned. Subsequent 
     * changes to the string buffer do not affect the contents of the 
     * <code>String</code>. 
     * <p>
     * Implementation advice: This method can be coded so as to create a new
     * <code>String</code> object without allocating new memory to hold a 
     * copy of the character sequence. Instead, the string can share the 
     * memory used by the string buffer. Any subsequent operation that alters 
     * the content or capacity of the string buffer must then make a copy of 
     * the internal buffer at that time. This strategy is effective for 
     * reducing the amount of memory allocated by a string concatenation 
     * operation when it is implemented using a string buffer.
     *
     * @return  a string representation of the string buffer.
     */
    public String toString() {
	return new String(this);
    }

    //
    // The following two methods are needed by String to efficiently
    // convert a StringBuffer into a String.  They are not public.
    // They shouldn't be called by anyone but String.
    final void setShared() { shared = true; } 
    final char[] getValue() { return value; }

    /**
     * readObject is called to restore the state of the StringBuffer from
     * a stream.
     */
    private synchronized void readObject(java.io.ObjectInputStream s)
         throws java.io.IOException, ClassNotFoundException {
	s.defaultReadObject();
	value = (char[]) value.clone();
	shared = false;
    }
}