/*

  * Copyright (c) 1994, 2008, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.  Oracle designates this

  * particular file as subject to the "Classpath" exception as provided

  * by Oracle in the LICENSE file that accompanied this code.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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  * questions.

  */

 package java.lang;

 /**

  * A thread-safe, mutable sequence of characters.

  * A string buffer is like a {@link String}, but can be modified. 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.

  * <p>

  * String buffers are safe for use by multiple threads. The methods

  * are synchronized where necessary so that all the operations on any

  * particular instance behave as if they occur in some serial order

  * that is consistent with the order of the method calls made by each of

  * the individual threads involved.

  * <p>

  * The principal operations on a <code>StringBuffer</code> are the

  * <code>append</code> and <code>insert</code> methods, which are

  * overloaded so as to accept data of any type. Each effectively

  * converts a given datum to a string and then appends or inserts the

  * characters of that string to the string buffer. The

  * <code>append</code> method always adds these characters at the end

  * of the buffer; the <code>insert</code> method adds the characters at

  * a specified point.

  * <p>

  * For example, if <code>z</code> refers to a string buffer object

  * whose current contents are "<code>start</code>", then

  * the method call <code>z.append("le")</code> would cause the string

  * buffer to contain "<code>startle</code>", whereas

  * <code>z.insert(4, "le")</code> would alter the string buffer to

  * contain "<code>starlet</code>".

  * <p>

  * In general, if sb refers to an instance of a <code>StringBuffer</code>,

  * then <code>sb.append(x)</code> has the same effect as

  * <code>sb.insert(sb.length(),&nbsp;x)</code>.

  * <p>

  * Whenever an operation occurs involving a source sequence (such as

  * appending or inserting from a source sequence) this class synchronizes

  * only on the string buffer performing the operation, not on the source.

  * <p>

  * Every string buffer has a capacity. As long as the length of the

  * character sequence contained in the string buffer does not exceed

  * the capacity, it is not necessary to allocate a new internal

  * buffer array. If the internal buffer overflows, it is

  * automatically made larger.

  *

  * As of  release JDK 5, this class has been supplemented with an equivalent

  * class designed for use by a single thread, {@link StringBuilder}.  The

  * <tt>StringBuilder</tt> class should generally be used in preference to

  * this one, as it supports all of the same operations but it is faster, as

  * it performs no synchronization.

  *

  * @author      Arthur van Hoff

  * @see     java.lang.StringBuilder

  * @see     java.lang.String

  * @since   JDK1.0

  */

  public final class StringBuffer

     extends AbstractStringBuilder

     implements java.io.Serializable, CharSequence

 {

     /** use serialVersionUID from JDK 1.0.2 for interoperability */

     static final long serialVersionUID = 3388685877147921107L;

     /**

      * Constructs a string buffer with no characters in it and an

      * initial capacity of 16 characters.

      */

     public StringBuffer() {

         super(16);

     }

     /**

      * Constructs a string buffer with no characters in it and

      * the specified initial capacity.

      *

      * @param      capacity  the initial capacity.

      * @exception  NegativeArraySizeException  if the <code>capacity</code>

      *               argument is less than <code>0</code>.

      */

     public StringBuffer(int capacity) {

         super(capacity);

     }

     /**

      * Constructs a string buffer initialized to the contents of the

      * specified string. The initial capacity of the string buffer is

      * <code>16</code> plus the length of the string argument.

      *

      * @param   str   the initial contents of the buffer.

      * @exception NullPointerException if <code>str</code> is <code>null</code>

      */

     public StringBuffer(String str) {

         super(str.length() + 16);

         append(str);

     }

     /**

      * Constructs a string buffer that contains the same characters

      * as the specified <code>CharSequence</code>. The initial capacity of

      * the string buffer is <code>16</code> plus the length of the

      * <code>CharSequence</code> argument.

      * <p>

      * If the length of the specified <code>CharSequence</code> is

      * less than or equal to zero, then an empty buffer of capacity

      * <code>16</code> is returned.

      *

      * @param      seq   the sequence to copy.

      * @exception NullPointerException if <code>seq</code> is <code>null</code>

      * @since 1.5

      */

     public StringBuffer(CharSequence seq) {

         this(seq.length() + 16);

         append(seq);

     }

     public synchronized int length() {

         return count;

     }

     public synchronized int capacity() {

         return value.length;

     }

     public synchronized void ensureCapacity(int minimumCapacity) {

         if (minimumCapacity > value.length) {

             expandCapacity(minimumCapacity);

         }

     }

     /**

      * @since      1.5

      */

     public synchronized void trimToSize() {

         super.trimToSize();

     }

     /**

      * @throws IndexOutOfBoundsException {@inheritDoc}

      * @see        #length()

      */

     public synchronized void setLength(int newLength) {

         super.setLength(newLength);

     }

     /**

      * @throws IndexOutOfBoundsException {@inheritDoc}

      * @see        #length()

      */

     public synchronized char charAt(int index) {

         if ((index < 0) || (index >= count))

             throw new StringIndexOutOfBoundsException(index);

         return value[index];

     }

     /**

      * @since      1.5

      */

     public synchronized int codePointAt(int index) {

         return super.codePointAt(index);

     }

     /**

      * @since     1.5

      */

     public synchronized int codePointBefore(int index) {

         return super.codePointBefore(index);

     }

     /**

      * @since     1.5

      */

     public synchronized int codePointCount(int beginIndex, int endIndex) {

         return super.codePointCount(beginIndex, endIndex);

     }

     /**

      * @since     1.5

      */

     public synchronized int offsetByCodePoints(int index, int codePointOffset) {

         return super.offsetByCodePoints(index, codePointOffset);

     }

     /**

      * @throws NullPointerException {@inheritDoc}

      * @throws IndexOutOfBoundsException {@inheritDoc}

      */

     public synchronized void getChars(int srcBegin, int srcEnd, char[] dst,

                                       int dstBegin)

     {

         super.getChars(srcBegin, srcEnd, dst, dstBegin);

     }

     /**

      * @throws IndexOutOfBoundsException {@inheritDoc}

      * @see        #length()

      */

     public synchronized void setCharAt(int index, char ch) {

         if ((index < 0) || (index >= count))

             throw new StringIndexOutOfBoundsException(index);

         value[index] = ch;

     }

     public synchronized StringBuffer append(Object obj) {

         super.append(String.valueOf(obj));

         return this;

     }

     public synchronized StringBuffer append(String str) {

         super.append(str);

         return this;

     }

     /**

      * Appends the specified <tt>StringBuffer</tt> to this sequence.

      * <p>

      * The characters of the <tt>StringBuffer</tt> argument are appended,

      * in order, to the contents of this <tt>StringBuffer</tt>, increasing the

      * length of this <tt>StringBuffer</tt> by the length of the argument.

      * If <tt>sb</tt> is <tt>null</tt>, then the four characters

      * <tt>"null"</tt> are appended to this <tt>StringBuffer</tt>.

      * <p>

      * Let <i>n</i> be the length of the old character sequence, the one

      * contained in the <tt>StringBuffer</tt> just prior to execution of the

      * <tt>append</tt> 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>sb</code>.

      * <p>

      * This method synchronizes on <code>this</code> (the destination)

      * object but does not synchronize on the source (<code>sb</code>).

      *

      * @param   sb   the <tt>StringBuffer</tt> to append.

      * @return  a reference to this object.

      * @since 1.4

      */

     public synchronized StringBuffer append(StringBuffer sb) {

         super.append(sb);

         return this;

     }

     /**

      * Appends the specified <code>CharSequence</code> to this

      * sequence.

      * <p>

      * The characters of the <code>CharSequence</code> argument are appended,

      * in order, increasing the length of this sequence by the length of the

      * argument.

      *

      * <p>The result of this method is exactly the same as if it were an

      * invocation of this.append(s, 0, s.length());

      *

      * <p>This method synchronizes on this (the destination)

      * object but does not synchronize on the source (<code>s</code>).

      *

      * <p>If <code>s</code> is <code>null</code>, then the four characters

      * <code>"null"</code> are appended.

      *

      * @param   s the <code>CharSequence</code> to append.

      * @return  a reference to this object.

      * @since 1.5

      */

     public StringBuffer append(CharSequence s) {

         // Note, synchronization achieved via other invocations

         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());

     }

     /**

      * @throws IndexOutOfBoundsException {@inheritDoc}

      * @since      1.5

      */

     public synchronized StringBuffer append(CharSequence s, int start, int end)

     {

         super.append(s, start, end);

         return this;

     }

     public synchronized StringBuffer append(char[] str) {

         super.append(str);

         return this;

     }

     /**

      * @throws IndexOutOfBoundsException {@inheritDoc}

      */

     public synchronized StringBuffer append(char[] str, int offset, int len) {

         super.append(str, offset, len);

         return this;

     }

     public synchronized StringBuffer append(boolean b) {

         super.append(b);

         return this;

     }

     public synchronized StringBuffer append(char c) {

         super.append(c);

         return this;

     }

     public synchronized StringBuffer append(int i) {

         super.append(i);

         return this;

     }

     /**

      * @since 1.5

      */

     public synchronized StringBuffer appendCodePoint(int codePoint) {

         super.appendCodePoint(codePoint);

         return this;

     }

     public synchronized StringBuffer append(long lng) {

         super.append(lng);

         return this;

     }

     public synchronized StringBuffer append(float f) {

         super.append(f);

         return this;

     }

     public synchronized StringBuffer append(double d) {

         super.append(d);

         return this;

     }

     /**

      * @throws StringIndexOutOfBoundsException {@inheritDoc}

      * @since      1.2

      */

     public synchronized StringBuffer delete(int start, int end) {

         super.delete(start, end);

         return this;

     }

     /**

      * @throws StringIndexOutOfBoundsException {@inheritDoc}

      * @since      1.2

      */

     public synchronized StringBuffer deleteCharAt(int index) {

         super.deleteCharAt(index);

         return this;

     }

     /**

      * @throws StringIndexOutOfBoundsException {@inheritDoc}

      * @since      1.2

      */

     public synchronized StringBuffer replace(int start, int end, String str) {

         super.replace(start, end, str);

         return this;

     }

     /**

      * @throws StringIndexOutOfBoundsException {@inheritDoc}

      * @since      1.2

      */

     public synchronized String substring(int start) {

         return substring(start, count);

     }

     /**

      * @throws IndexOutOfBoundsException {@inheritDoc}

      * @since      1.4

      */

     public synchronized CharSequence subSequence(int start, int end) {

         return super.substring(start, end);

     }

     /**

      * @throws StringIndexOutOfBoundsException {@inheritDoc}

      * @since      1.2

      */

     public synchronized String substring(int start, int end) {

         return super.substring(start, end);

     }

     /**

      * @throws StringIndexOutOfBoundsException {@inheritDoc}

      * @since      1.2

      */

     public synchronized StringBuffer insert(int index, char[] str, int offset,

                                             int len)

     {

         super.insert(index, str, offset, len);

         return this;

     }

     /**

      * @throws StringIndexOutOfBoundsException {@inheritDoc}

      */

     public synchronized StringBuffer insert(int offset, Object obj) {

         super.insert(offset, String.valueOf(obj));

         return this;

     }

     /**

      * @throws StringIndexOutOfBoundsException {@inheritDoc}

      */

     public synchronized StringBuffer insert(int offset, String str) {

         super.insert(offset, str);

         return this;

     }

     /**

      * @throws StringIndexOutOfBoundsException {@inheritDoc}

      */

     public synchronized StringBuffer insert(int offset, char[] str) {

         super.insert(offset, str);

         return this;

     }

     /**

      * @throws IndexOutOfBoundsException {@inheritDoc}

      * @since      1.5

      */

     public StringBuffer insert(int dstOffset, CharSequence s) {

         // Note, synchronization achieved via other invocations

         if (s == null)

             s = "null";

         if (s instanceof String)

             return this.insert(dstOffset, (String)s);

         return this.insert(dstOffset, s, 0, s.length());

     }

     /**

      * @throws IndexOutOfBoundsException {@inheritDoc}

      * @since      1.5

      */

     public synchronized StringBuffer insert(int dstOffset, CharSequence s,

                                             int start, int end)

     {

         super.insert(dstOffset, s, start, end);

         return this;

     }

     /**

      * @throws StringIndexOutOfBoundsException {@inheritDoc}

      */

     public StringBuffer insert(int offset, boolean b) {

         return insert(offset, String.valueOf(b));

     }

     /**

      * @throws IndexOutOfBoundsException {@inheritDoc}

      */

     public synchronized StringBuffer insert(int offset, char c) {

         super.insert(offset, c);

         return this;

     }

     /**

      * @throws StringIndexOutOfBoundsException {@inheritDoc}

      */

     public StringBuffer insert(int offset, int i) {

         return insert(offset, String.valueOf(i));

     }

     /**

      * @throws StringIndexOutOfBoundsException {@inheritDoc}

      */

     public StringBuffer insert(int offset, long l) {

         return insert(offset, String.valueOf(l));

     }

     /**

      * @throws StringIndexOutOfBoundsException {@inheritDoc}

      */

     public StringBuffer insert(int offset, float f) {

         return insert(offset, String.valueOf(f));

     }

     /**

      * @throws StringIndexOutOfBoundsException {@inheritDoc}

      */

     public StringBuffer insert(int offset, double d) {

         return insert(offset, String.valueOf(d));

     }

     /**

      * @throws NullPointerException {@inheritDoc}

      * @since      1.4

      */

     public int indexOf(String str) {

         return indexOf(str, 0);

     }

     /**

      * @throws NullPointerException {@inheritDoc}

      * @since      1.4

      */

     public synchronized int indexOf(String str, int fromIndex) {

         return super.indexOf(str, fromIndex);

     }

     /**

      * @throws NullPointerException {@inheritDoc}

      * @since      1.4

      */

     public int lastIndexOf(String str) {

         // Note, synchronization achieved via other invocations

         return lastIndexOf(str, count);

     }

     /**

      * @throws NullPointerException {@inheritDoc}

      * @since      1.4

      */

     public synchronized int lastIndexOf(String str, int fromIndex) {

         return String.lastIndexOf(value, 0, count,

                               str.toCharArray(), 0, str.length(), fromIndex);

     }

     /**

      * @since   JDK1.0.2

      */

     public synchronized StringBuffer reverse() {

         super.reverse();

         return this;

     }

     public synchronized String toString() {

         return new String(value, 0, count);

     }

 //    /**

 //     * Serializable fields for StringBuffer.

 //     *

 //     * @serialField value  char[]

 //     *              The backing character array of this StringBuffer.

 //     * @serialField count int

 //     *              The number of characters in this StringBuffer.

 //     * @serialField shared  boolean

 //     *              A flag indicating whether the backing array is shared.

 //     *              The value is ignored upon deserialization.

 //     */

 //    private static final java.io.ObjectStreamField[] serialPersistentFields =

 //    {

 //        new java.io.ObjectStreamField("value", char[].class),

 //        new java.io.ObjectStreamField("count", Integer.TYPE),

 //        new java.io.ObjectStreamField("shared", Boolean.TYPE),

 //    };

 //

 //    /**

 //     * readObject is called to restore the state of the StringBuffer from

 //     * a stream.

 //     */

 //    private synchronized void writeObject(java.io.ObjectOutputStream s)

 //        throws java.io.IOException {

 //        java.io.ObjectOutputStream.PutField fields = s.putFields();

 //        fields.put("value", value);

 //        fields.put("count", count);

 //        fields.put("shared", false);

 //        s.writeFields();

 //    }

 //

 //    /**

 //     * readObject is called to restore the state of the StringBuffer from

 //     * a stream.

 //     */

 //    private void readObject(java.io.ObjectInputStream s)

 //        throws java.io.IOException, ClassNotFoundException {

 //        java.io.ObjectInputStream.GetField fields = s.readFields();

 //        value = (char[])fields.get("value", null);

 //        count = fields.get("count", 0);

 //    }

 }