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	/*
	* Copyright (c) 1994, 2018, 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
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.lang;

	import java.util.Arrays;
	import jdk.internal.HotSpotIntrinsicCandidate;

	/**
	* 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} are the
	* {@code append} and {@code insert} 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} method always adds these characters at the end
	* of the buffer; the {@code insert} method adds the characters at
	* a specified point.
	* <p>
	* For example, if {@code z} refers to a string buffer object
	* whose current contents are {@code "start"}, then
	* the method call {@code z.append("le")} would cause the string
	* buffer to contain {@code "startle"}, whereas
	* {@code z.insert(4, "le")} would alter the string buffer to
	* contain {@code "starlet"}.
	* <p>
	* In general, if sb refers to an instance of a {@code StringBuffer},
	* then {@code sb.append(x)} has the same effect as
	* {@code sb.insert(sb.length(), x)}.
	* <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.
	* Note that while {@code StringBuffer} is designed to be safe to use
	* concurrently from multiple threads, if the constructor or the
	* {@code append} or {@code insert} operation is passed a source sequence
	* that is shared across threads, the calling code must ensure
	* that the operation has a consistent and unchanging view of the source
	* sequence for the duration of the operation.
	* This could be satisfied by the caller holding a lock during the
	* operation's call, by using an immutable source sequence, or by not
	* sharing the source sequence across threads.
	* <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.
	* <p>
	* Unless otherwise noted, passing a {@code null} argument to a constructor
	* or method in this class will cause a {@link NullPointerException} to be
	* thrown.
	* <p>
	* As of release JDK 5, this class has been supplemented with an equivalent
	* class designed for use by a single thread, {@link StringBuilder}. The
	* {@code StringBuilder} 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.
	*
	* @apiNote
	* {@code StringBuffer} implements {@code Comparable} but does not override
	* {@link Object#equals equals}. Thus, the natural ordering of {@code StringBuffer}
	* is inconsistent with equals. Care should be exercised if {@code StringBuffer}
	* objects are used as keys in a {@code SortedMap} or elements in a {@code SortedSet}.
	* See {@link Comparable}, {@link java.util.SortedMap SortedMap}, or
	* {@link java.util.SortedSet SortedSet} for more information.
	*
	* @author Arthur van Hoff
	* @see java.lang.StringBuilder
	* @see java.lang.String
	* @since 1.0
	*/
	public final class StringBuffer
	extends AbstractStringBuilder
	implements java.io.Serializable, Comparable<StringBuffer>, CharSequence
	{

	/**
	* A cache of the last value returned by toString. Cleared
	* whenever the StringBuffer is modified.
	*/
	private transient String toStringCache;

	/** 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.
	*/
	@HotSpotIntrinsicCandidate
	public StringBuffer() {
	super(16);
	}

	/**
	* Constructs a string buffer with no characters in it and
	* the specified initial capacity.
	*
	* @param capacity the initial capacity.
	* @throws NegativeArraySizeException if the {@code capacity}
	* argument is less than {@code 0}.
	*/
	@HotSpotIntrinsicCandidate
	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} plus the length of the string argument.
	*
	* @param str the initial contents of the buffer.
	*/
	@HotSpotIntrinsicCandidate
	public StringBuffer(String str) {
	super(str.length() + 16);
	append(str);
	}

	/**
	* Constructs a string buffer that contains the same characters
	* as the specified {@code CharSequence}. The initial capacity of
	* the string buffer is {@code 16} plus the length of the
	* {@code CharSequence} argument.
	* <p>
	* If the length of the specified {@code CharSequence} is
	* less than or equal to zero, then an empty buffer of capacity
	* {@code 16} is returned.
	*
	* @param seq the sequence to copy.
	* @since 1.5
	*/
	public StringBuffer(CharSequence seq) {
	this(seq.length() + 16);
	append(seq);
	}

	/**
	* Compares two {@code StringBuffer} instances lexicographically. This method
	* follows the same rules for lexicographical comparison as defined in the
	* {@linkplain java.lang.CharSequence#compare(java.lang.CharSequence,
	* java.lang.CharSequence) CharSequence.compare(this, another)} method.
	*
	* <p>
	* For finer-grained, locale-sensitive String comparison, refer to
	* {@link java.text.Collator}.
	*
	* @implNote
	* This method synchronizes on {@code this}, the current object, but not
	* {@code StringBuffer another} with which {@code this StringBuffer} is compared.
	*
	* @param another the {@code StringBuffer} to be compared with
	*
	* @return the value {@code 0} if this {@code StringBuffer} contains the same
	* character sequence as that of the argument {@code StringBuffer}; a negative integer
	* if this {@code StringBuffer} is lexicographically less than the
	* {@code StringBuffer} argument; or a positive integer if this {@code StringBuffer}
	* is lexicographically greater than the {@code StringBuffer} argument.
	*
	* @since 11
	*/
	@Override
	public synchronized int compareTo(StringBuffer another) {
	return super.compareTo(another);
	}

	@Override
	public synchronized int length() {
	return count;
	}

	@Override
	public synchronized int capacity() {
	return super.capacity();
	}


	@Override
	public synchronized void ensureCapacity(int minimumCapacity) {
	super.ensureCapacity(minimumCapacity);
	}

	/**
	* @since 1.5
	*/
	@Override
	public synchronized void trimToSize() {
	super.trimToSize();
	}

	/**
	* @throws IndexOutOfBoundsException {@inheritDoc}
	* @see #length()
	*/
	@Override
	public synchronized void setLength(int newLength) {
	toStringCache = null;
	super.setLength(newLength);
	}

	/**
	* @throws IndexOutOfBoundsException {@inheritDoc}
	* @see #length()
	*/
	@Override
	public synchronized char charAt(int index) {
	return super.charAt(index);
	}

	/**
	* @throws IndexOutOfBoundsException {@inheritDoc}
	* @since 1.5
	*/
	@Override
	public synchronized int codePointAt(int index) {
	return super.codePointAt(index);
	}

	/**
	* @throws IndexOutOfBoundsException {@inheritDoc}
	* @since 1.5
	*/
	@Override
	public synchronized int codePointBefore(int index) {
	return super.codePointBefore(index);
	}

	/**
	* @throws IndexOutOfBoundsException {@inheritDoc}
	* @since 1.5
	*/
	@Override
	public synchronized int codePointCount(int beginIndex, int endIndex) {
	return super.codePointCount(beginIndex, endIndex);
	}

	/**
	* @throws IndexOutOfBoundsException {@inheritDoc}
	* @since 1.5
	*/
	@Override
	public synchronized int offsetByCodePoints(int index, int codePointOffset) {
	return super.offsetByCodePoints(index, codePointOffset);
	}

	/**
	* @throws IndexOutOfBoundsException {@inheritDoc}
	*/
	@Override
	public synchronized void getChars(int srcBegin, int srcEnd, char[] dst,
	int dstBegin)
	{
	super.getChars(srcBegin, srcEnd, dst, dstBegin);
	}

	/**
	* @throws IndexOutOfBoundsException {@inheritDoc}
	* @see #length()
	*/
	@Override
	public synchronized void setCharAt(int index, char ch) {
	toStringCache = null;
	super.setCharAt(index, ch);
	}

	@Override
	public synchronized StringBuffer append(Object obj) {
	toStringCache = null;
	super.append(String.valueOf(obj));
	return this;
	}

	@Override
	@HotSpotIntrinsicCandidate
	public synchronized StringBuffer append(String str) {
	toStringCache = null;
	super.append(str);
	return this;
	}

	/**
	* Appends the specified {@code StringBuffer} to this sequence.
	* <p>
	* The characters of the {@code StringBuffer} argument are appended,
	* in order, to the contents of this {@code StringBuffer}, increasing the
	* length of this {@code StringBuffer} by the length of the argument.
	* If {@code sb} is {@code null}, then the four characters
	* {@code "null"} are appended to this {@code StringBuffer}.
	* <p>
	* Let <i>n</i> be the length of the old character sequence, the one
	* contained in the {@code StringBuffer} just prior to execution of the
	* {@code append} 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}.
	* <p>
	* This method synchronizes on {@code this}, the destination
	* object, but does not synchronize on the source ({@code sb}).
	*
	* @param sb the {@code StringBuffer} to append.
	* @return a reference to this object.
	* @since 1.4
	*/
	public synchronized StringBuffer append(StringBuffer sb) {
	toStringCache = null;
	super.append(sb);
	return this;
	}

	/**
	* @since 1.8
	*/
	@Override
	synchronized StringBuffer append(AbstractStringBuilder asb) {
	toStringCache = null;
	super.append(asb);
	return this;
	}

	/**
	* Appends the specified {@code CharSequence} to this
	* sequence.
	* <p>
	* The characters of the {@code CharSequence} 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 {@code this}, the destination
	* object, but does not synchronize on the source ({@code s}).
	*
	* <p>If {@code s} is {@code null}, then the four characters
	* {@code "null"} are appended.
	*
	* @param s the {@code CharSequence} to append.
	* @return a reference to this object.
	* @since 1.5
	*/
	@Override
	public synchronized StringBuffer append(CharSequence s) {
	toStringCache = null;
	super.append(s);
	return this;
	}

	/**
	* @throws IndexOutOfBoundsException {@inheritDoc}
	* @since 1.5
	*/
	@Override
	public synchronized StringBuffer append(CharSequence s, int start, int end)
	{
	toStringCache = null;
	super.append(s, start, end);
	return this;
	}

	@Override
	public synchronized StringBuffer append(char[] str) {
	toStringCache = null;
	super.append(str);
	return this;
	}

	/**
	* @throws IndexOutOfBoundsException {@inheritDoc}
	*/
	@Override
	public synchronized StringBuffer append(char[] str, int offset, int len) {
	toStringCache = null;
	super.append(str, offset, len);
	return this;
	}

	@Override
	public synchronized StringBuffer append(boolean b) {
	toStringCache = null;
	super.append(b);
	return this;
	}

	@Override
	@HotSpotIntrinsicCandidate
	public synchronized StringBuffer append(char c) {
	toStringCache = null;
	super.append(c);
	return this;
	}

	@Override
	@HotSpotIntrinsicCandidate
	public synchronized StringBuffer append(int i) {
	toStringCache = null;
	super.append(i);
	return this;
	}

	/**
	* @since 1.5
	*/
	@Override
	public synchronized StringBuffer appendCodePoint(int codePoint) {
	toStringCache = null;
	super.appendCodePoint(codePoint);
	return this;
	}

	@Override
	public synchronized StringBuffer append(long lng) {
	toStringCache = null;
	super.append(lng);
	return this;
	}

	@Override
	public synchronized StringBuffer append(float f) {
	toStringCache = null;
	super.append(f);
	return this;
	}

	@Override
	public synchronized StringBuffer append(double d) {
	toStringCache = null;
	super.append(d);
	return this;
	}

	/**
	* @throws StringIndexOutOfBoundsException {@inheritDoc}
	* @since 1.2
	*/
	@Override
	public synchronized StringBuffer delete(int start, int end) {
	toStringCache = null;
	super.delete(start, end);
	return this;
	}

	/**
	* @throws StringIndexOutOfBoundsException {@inheritDoc}
	* @since 1.2
	*/
	@Override
	public synchronized StringBuffer deleteCharAt(int index) {
	toStringCache = null;
	super.deleteCharAt(index);
	return this;
	}

	/**
	* @throws StringIndexOutOfBoundsException {@inheritDoc}
	* @since 1.2
	*/
	@Override
	public synchronized StringBuffer replace(int start, int end, String str) {
	toStringCache = null;
	super.replace(start, end, str);
	return this;
	}

	/**
	* @throws StringIndexOutOfBoundsException {@inheritDoc}
	* @since 1.2
	*/
	@Override
	public synchronized String substring(int start) {
	return substring(start, count);
	}

	/**
	* @throws IndexOutOfBoundsException {@inheritDoc}
	* @since 1.4
	*/
	@Override
	public synchronized CharSequence subSequence(int start, int end) {
	return super.substring(start, end);
	}

	/**
	* @throws StringIndexOutOfBoundsException {@inheritDoc}
	* @since 1.2
	*/
	@Override
	public synchronized String substring(int start, int end) {
	return super.substring(start, end);
	}

	/**
	* @throws StringIndexOutOfBoundsException {@inheritDoc}
	* @since 1.2
	*/
	@Override
	public synchronized StringBuffer insert(int index, char[] str, int offset,
	int len)
	{
	toStringCache = null;
	super.insert(index, str, offset, len);
	return this;
	}

	/**
	* @throws StringIndexOutOfBoundsException {@inheritDoc}
	*/
	@Override
	public synchronized StringBuffer insert(int offset, Object obj) {
	toStringCache = null;
	super.insert(offset, String.valueOf(obj));
	return this;
	}

	/**
	* @throws StringIndexOutOfBoundsException {@inheritDoc}
	*/
	@Override
	public synchronized StringBuffer insert(int offset, String str) {
	toStringCache = null;
	super.insert(offset, str);
	return this;
	}

	/**
	* @throws StringIndexOutOfBoundsException {@inheritDoc}
	*/
	@Override
	public synchronized StringBuffer insert(int offset, char[] str) {
	toStringCache = null;
	super.insert(offset, str);
	return this;
	}

	/**
	* @throws IndexOutOfBoundsException {@inheritDoc}
	* @since 1.5
	*/
	@Override
	public StringBuffer insert(int dstOffset, CharSequence s) {
	// Note, synchronization achieved via invocations of other StringBuffer methods
	// after narrowing of s to specific type
	// Ditto for toStringCache clearing
	super.insert(dstOffset, s);
	return this;
	}

	/**
	* @throws IndexOutOfBoundsException {@inheritDoc}
	* @since 1.5
	*/
	@Override
	public synchronized StringBuffer insert(int dstOffset, CharSequence s,
	int start, int end)
	{
	toStringCache = null;
	super.insert(dstOffset, s, start, end);
	return this;
	}

	/**
	* @throws StringIndexOutOfBoundsException {@inheritDoc}
	*/
	@Override
	public StringBuffer insert(int offset, boolean b) {
	// Note, synchronization achieved via invocation of StringBuffer insert(int, String)
	// after conversion of b to String by super class method
	// Ditto for toStringCache clearing
	super.insert(offset, b);
	return this;
	}

	/**
	* @throws IndexOutOfBoundsException {@inheritDoc}
	*/
	@Override
	public synchronized StringBuffer insert(int offset, char c) {
	toStringCache = null;
	super.insert(offset, c);
	return this;
	}

	/**
	* @throws StringIndexOutOfBoundsException {@inheritDoc}
	*/
	@Override
	public StringBuffer insert(int offset, int i) {
	// Note, synchronization achieved via invocation of StringBuffer insert(int, String)
	// after conversion of i to String by super class method
	// Ditto for toStringCache clearing
	super.insert(offset, i);
	return this;
	}

	/**
	* @throws StringIndexOutOfBoundsException {@inheritDoc}
	*/
	@Override
	public StringBuffer insert(int offset, long l) {
	// Note, synchronization achieved via invocation of StringBuffer insert(int, String)
	// after conversion of l to String by super class method
	// Ditto for toStringCache clearing
	super.insert(offset, l);
	return this;
	}

	/**
	* @throws StringIndexOutOfBoundsException {@inheritDoc}
	*/
	@Override
	public StringBuffer insert(int offset, float f) {
	// Note, synchronization achieved via invocation of StringBuffer insert(int, String)
	// after conversion of f to String by super class method
	// Ditto for toStringCache clearing
	super.insert(offset, f);
	return this;
	}

	/**
	* @throws StringIndexOutOfBoundsException {@inheritDoc}
	*/
	@Override
	public StringBuffer insert(int offset, double d) {
	// Note, synchronization achieved via invocation of StringBuffer insert(int, String)
	// after conversion of d to String by super class method
	// Ditto for toStringCache clearing
	super.insert(offset, d);
	return this;
	}

	/**
	* @since 1.4
	*/
	@Override
	public int indexOf(String str) {
	// Note, synchronization achieved via invocations of other StringBuffer methods
	return super.indexOf(str);
	}

	/**
	* @since 1.4
	*/
	@Override
	public synchronized int indexOf(String str, int fromIndex) {
	return super.indexOf(str, fromIndex);
	}

	/**
	* @since 1.4
	*/
	@Override
	public int lastIndexOf(String str) {
	// Note, synchronization achieved via invocations of other StringBuffer methods
	return lastIndexOf(str, count);
	}

	/**
	* @since 1.4
	*/
	@Override
	public synchronized int lastIndexOf(String str, int fromIndex) {
	return super.lastIndexOf(str, fromIndex);
	}

	/**
	* @since 1.0.2
	*/
	@Override
	public synchronized StringBuffer reverse() {
	toStringCache = null;
	super.reverse();
	return this;
	}

	@Override
	@HotSpotIntrinsicCandidate
	public synchronized String toString() {
	if (toStringCache == null) {
	return toStringCache =
	isLatin1() ? StringLatin1.newString(value, 0, count)
	: StringUTF16.newString(value, 0, count);
	}
	return new String(toStringCache);
	}

	/**
	* 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();
	char[] val = new char[capacity()];
	if (isLatin1()) {
	StringLatin1.getChars(value, 0, count, val, 0);
	} else {
	StringUTF16.getChars(value, 0, count, val, 0);
	}
	fields.put("value", val);
	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();
	char[] val = (char[])fields.get("value", null);
	initBytes(val, 0, val.length);
	count = fields.get("count", 0);
	}

	synchronized void getBytes(byte dst[], int dstBegin, byte coder) {
	super.getBytes(dst, dstBegin, coder);
	}
	}

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