CharBuffer源码解读

public abstract class CharBuffer extends Buffer implements
		Comparable<CharBuffer>, Appendable, CharSequence, Readable {

	
	final char[] hb; //指向缓冲区的数据存储的引用
	final int offset;
	boolean isReadOnly; 

	
	CharBuffer(int mark, int pos, int lim, int cap, 
			char[] hb, int offset) {
		super(mark, pos, lim, cap);
		this.hb = hb;
		this.offset = offset;
	}

	CharBuffer(int mark, int pos, int lim, int cap) { 
		this(mark, pos, lim, cap, null, 0);
	}

	//静态工厂方法，创建HeapCharBuffer对象
	/*
	 * HeapCharBuffer(int cap, int lim) { 
	 *	super(-1, 0, lim, cap, new char[cap], 0);
	 * }
	 */
	//从HeapCharBuffer(capacity, capacity)的构造函数可以看出
	//这个方法将返回一个CharBuffer实例
	//mark=-1,pos=0,lim=cap;cap=cap,hb=new char[cap],offset=0
	public static CharBuffer allocate(int capacity) {
		if (capacity < 0)
			throw new IllegalArgumentException();
		return new HeapCharBuffer(capacity, capacity);
	}
	
	
	 //HeapCharBuffer(char[] buf, int off, int len) { 
	//	super(-1, off, off + len, buf.length, buf, 0);
	//	}
	//这个方法将返回一个CharBuffer实例
	//mark=-1,....
	public static CharBuffer wrap(char[] array, int offset, int length) {
		try {
			return new HeapCharBuffer(array, offset, length);
		} catch (IllegalArgumentException x) {
			throw new IndexOutOfBoundsException();
		}
	}

	
	public static CharBuffer wrap(char[] array) {
		return wrap(array, 0, array.length);
	}

	public static CharBuffer wrap(CharSequence csq, int start, int end) {
		try {
			return new StringCharBuffer(csq, start, end);
		} catch (IllegalArgumentException x) {
			throw new IndexOutOfBoundsException();
		}
	}

	
	 
	public static CharBuffer wrap(CharSequence csq) {
		return wrap(csq, 0, csq.length());
	}

	//
	public int read(CharBuffer target) throws IOException {
		// Determine the number of bytes n that can be transferred
		int targetRemaining = target.remaining();
		int remaining = remaining();
		if (remaining == 0)
			return -1;
		int n = Math.min(remaining, targetRemaining);
		int limit = limit();
		// Set source limit to prevent target overflow
		if (targetRemaining < remaining)
			limit(position() + n);
		try {
			if (n > 0)
				target.put(this);
		} finally {
			limit(limit); // restore real limit
		}
		return n;
	}

	/**
	 * Creates a new character buffer whose content is a shared subsequence of
	 * this buffer's content.
	 * 
	 * <p>
	 * The content of the new buffer will start at this buffer's current
	 * position. Changes to this buffer's content will be visible in the new
	 * buffer, and vice versa; the two buffers' position, limit, and mark values
	 * will be independent.
	 * 
	 * <p>
	 * The new buffer's position will be zero, its capacity and its limit will
	 * be the number of characters remaining in this buffer, and its mark will
	 * be undefined. The new buffer will be direct if, and only if, this buffer
	 * is direct, and it will be read-only if, and only if, this buffer is
	 * read-only.
	 * </p>
	 * 
	 * @return The new character buffer
	 */
	public abstract CharBuffer slice();

	/**
	 * Creates a new character buffer that shares this buffer's content.
	 * 
	 * <p>
	 * The content of the new buffer will be that of this buffer. Changes to
	 * this buffer's content will be visible in the new buffer, and vice versa;
	 * the two buffers' position, limit, and mark values will be independent.
	 * 
	 * <p>
	 * The new buffer's capacity, limit, position, and mark values will be
	 * identical to those of this buffer. The new buffer will be direct if, and
	 * only if, this buffer is direct, and it will be read-only if, and only if,
	 * this buffer is read-only.
	 * </p>
	 * 
	 * @return The new character buffer
	 */
	public abstract CharBuffer duplicate();

	/**
	 * Creates a new, read-only character buffer that shares this buffer's
	 * content.
	 * 
	 * <p>
	 * The content of the new buffer will be that of this buffer. Changes to
	 * this buffer's content will be visible in the new buffer; the new buffer
	 * itself, however, will be read-only and will not allow the shared content
	 * to be modified. The two buffers' position, limit, and mark values will be
	 * independent.
	 * 
	 * <p>
	 * The new buffer's capacity, limit, position, and mark values will be
	 * identical to those of this buffer.
	 * 
	 * <p>
	 * If this buffer is itself read-only then this method behaves in exactly
	 * the same way as the {@link #duplicate duplicate} method.
	 * </p>
	 * 
	 * @return The new, read-only character buffer
	 */
	public abstract CharBuffer asReadOnlyBuffer();

	// -- Singleton get/put methods --

	/**
	 * Relative <i>get</i> method. Reads the character at this buffer's current
	 * position, and then increments the position. </p>
	 * 
	 * @return The character at the buffer's current position
	 * 
	 * @throws BufferUnderflowException
	 *             If the buffer's current position is not smaller than its
	 *             limit
	 */
	public abstract char get();

	/**
	 * Relative <i>put</i> method&nbsp;&nbsp;<i>(optional operation)</i>.
	 * 
	 * <p>
	 * Writes the given character into this buffer at the current position, and
	 * then increments the position.
	 * </p>
	 * 
	 * @param c
	 *            The character to be written
	 * 
	 * @return This buffer
	 * 
	 * @throws BufferOverflowException
	 *             If this buffer's current position is not smaller than its
	 *             limit
	 * 
	 * @throws ReadOnlyBufferException
	 *             If this buffer is read-only
	 */
	public abstract CharBuffer put(char c);

	/**
	 * Absolute <i>get</i> method. Reads the character at the given index. </p>
	 * 
	 * @param index
	 *            The index from which the character will be read
	 * 
	 * @return The character at the given index
	 * 
	 * @throws IndexOutOfBoundsException
	 *             If <tt>index</tt> is negative or not smaller than the
	 *             buffer's limit
	 */
	public abstract char get(int index);

	/**
	 * Absolute <i>put</i> method&nbsp;&nbsp;<i>(optional operation)</i>.
	 * 
	 * <p>
	 * Writes the given character into this buffer at the given index.
	 * </p>
	 * 
	 * @param index
	 *            The index at which the character will be written
	 * 
	 * @param c
	 *            The character value to be written
	 * 
	 * @return This buffer
	 * 
	 * @throws IndexOutOfBoundsException
	 *             If <tt>index</tt> is negative or not smaller than the
	 *             buffer's limit
	 * 
	 * @throws ReadOnlyBufferException
	 *             If this buffer is read-only
	 */
	public abstract CharBuffer put(int index, char c);

	// -- Bulk get operations --

	/**
	 * Relative bulk <i>get</i> method.
	 * 
	 * <p>
	 * This method transfers characters from this buffer into the given
	 * destination array. If there are fewer characters remaining in the buffer
	 * than are required to satisfy the request, that is, if <tt>length</tt>
	 * &nbsp;<tt>&gt;</tt>&nbsp;<tt>remaining()</tt>, then no characters are
	 * transferred and a {@link BufferUnderflowException} is thrown.
	 * 
	 * <p>
	 * Otherwise, this method copies <tt>length</tt> characters from this buffer
	 * into the given array, starting at the current position of this buffer and
	 * at the given offset in the array. The position of this buffer is then
	 * incremented by <tt>length</tt>.
	 * 
	 * <p>
	 * In other words, an invocation of this method of the form
	 * <tt>src.get(dst,&nbsp;off,&nbsp;len)</tt> has exactly the same effect as
	 * the loop
	 * 
	 * <pre>
	 * for (int i = off; i &lt; off + len; i++)
	 * 	dst[i] = src.get();
	 * </pre>
	 * 
	 * except that it first checks that there are sufficient characters in this
	 * buffer and it is potentially much more efficient.
	 * </p>
	 * 
	 * @param dst
	 *            The array into which characters are to be written
	 * 
	 * @param offset
	 *            The offset within the array of the first character to be
	 *            written; must be non-negative and no larger than
	 *            <tt>dst.length</tt>
	 * 
	 * @param length
	 *            The maximum number of characters to be written to the given
	 *            array; must be non-negative and no larger than
	 *            <tt>dst.length - offset</tt>
	 * 
	 * @return This buffer
	 * 
	 * @throws BufferUnderflowException
	 *             If there are fewer than <tt>length</tt> characters remaining
	 *             in this buffer
	 * 
	 * @throws IndexOutOfBoundsException
	 *             If the preconditions on the <tt>offset</tt> and
	 *             <tt>length</tt> parameters do not hold
	 */
	//把缓冲区里的数据填到dst数组中，offset是dst数组开始要填充的位置，lenght表示要
	//填充的字符数。
	//如果缓冲区里剩余的字符数量小于希望填充的个数，抛出异常
	//数组要足够大
	public CharBuffer get(char[] dst, int offset, int length) {
		checkBounds(offset, length, dst.length);
		if (length > remaining())
			throw new BufferUnderflowException();
		int end = offset + length;
		for (int i = offset; i < end; i++)
			dst[i] = get();
		return this;
	}

	/**
	 * Relative bulk <i>get</i> method.
	 * 
	 * <p>
	 * This method transfers characters from this buffer into the given
	 * destination array. An invocation of this method of the form
	 * <tt>src.get(a)</tt> behaves in exactly the same way as the invocation
	 * 
	 * <pre>
	 * src.get(a, 0, a.length)
	 * </pre>
	 * 
	 * @return This buffer
	 * 
	 * @throws BufferUnderflowException
	 *             If there are fewer than <tt>length</tt> characters remaining
	 *             in this buffer
	 */
	public CharBuffer get(char[] dst) {
		return get(dst, 0, dst.length);
	}

	// -- Bulk put operations --

	/**
	 * Relative bulk <i>put</i> method&nbsp;&nbsp;<i>(optional operation)</i>.
	 * 
	 * <p>
	 * This method transfers the characters remaining in the given source buffer
	 * into this buffer. If there are more characters remaining in the source
	 * buffer than in this buffer, that is, if <tt>src.remaining()</tt>&nbsp;
	 * <tt>&gt;</tt>&nbsp;<tt>remaining()</tt>, then no characters are
	 * transferred and a {@link BufferOverflowException} is thrown.
	 * 
	 * <p>
	 * Otherwise, this method copies <i>n</i>&nbsp;=&nbsp;
	 * <tt>src.remaining()</tt> characters from the given buffer into this
	 * buffer, starting at each buffer's current position. The positions of both
	 * buffers are then incremented by <i>n</i>.
	 * 
	 * <p>
	 * In other words, an invocation of this method of the form
	 * <tt>dst.put(src)</tt> has exactly the same effect as the loop
	 * 
	 * <pre>
	 * while (src.hasRemaining())
	 * 	dst.put(src.get());
	 * </pre>
	 * 
	 * except that it first checks that there is sufficient space in this buffer
	 * and it is potentially much more efficient.
	 * </p>
	 * 
	 * @param src
	 *            The source buffer from which characters are to be read; must
	 *            not be this buffer
	 * 
	 * @return This buffer
	 * 
	 * @throws BufferOverflowException
	 *             If there is insufficient space in this buffer for the
	 *             remaining characters in the source buffer
	 * 
	 * @throws IllegalArgumentException
	 *             If the source buffer is this buffer
	 * 
	 * @throws ReadOnlyBufferException
	 *             If this buffer is read-only
	 */
	public CharBuffer put(CharBuffer src) {
		if (src == this)
			throw new IllegalArgumentException();
		int n = src.remaining();
		if (n > remaining())
			throw new BufferOverflowException();
		for (int i = 0; i < n; i++)
			put(src.get());
		return this;
	}

	/**
	 * Relative bulk <i>put</i> method&nbsp;&nbsp;<i>(optional operation)</i>.
	 * 
	 * <p>
	 * This method transfers characters into this buffer from the given source
	 * array. If there are more characters to be copied from the array than
	 * remain in this buffer, that is, if <tt>length</tt>&nbsp;<tt>&gt;</tt>
	 * &nbsp;<tt>remaining()</tt>, then no characters are transferred and a
	 * {@link BufferOverflowException} is thrown.
	 * 
	 * <p>
	 * Otherwise, this method copies <tt>length</tt> characters from the given
	 * array into this buffer, starting at the given offset in the array and at
	 * the current position of this buffer. The position of this buffer is then
	 * incremented by <tt>length</tt>.
	 * 
	 * <p>
	 * In other words, an invocation of this method of the form
	 * <tt>dst.put(src,&nbsp;off,&nbsp;len)</tt> has exactly the same effect as
	 * the loop
	 * 
	 * <pre>
	 * for (int i = off; i &lt; off + len; i++)
	 * 	dst.put(a[i]);
	 * </pre>
	 * 
	 * except that it first checks that there is sufficient space in this buffer
	 * and it is potentially much more efficient.
	 * </p>
	 * 
	 * @param src
	 *            The array from which characters are to be read
	 * 
	 * @param offset
	 *            The offset within the array of the first character to be read;
	 *            must be non-negative and no larger than <tt>array.length</tt>
	 * 
	 * @param length
	 *            The number of characters to be read from the given array; must
	 *            be non-negative and no larger than
	 *            <tt>array.length - offset</tt>
	 * 
	 * @return This buffer
	 * 
	 * @throws BufferOverflowException
	 *             If there is insufficient space in this buffer
	 * 
	 * @throws IndexOutOfBoundsException
	 *             If the preconditions on the <tt>offset</tt> and
	 *             <tt>length</tt> parameters do not hold
	 * 
	 * @throws ReadOnlyBufferException
	 *             If this buffer is read-only
	 */
	public CharBuffer put(char[] src, int offset, int length) {
		checkBounds(offset, length, src.length);
		if (length > remaining())
			throw new BufferOverflowException();
		int end = offset + length;
		for (int i = offset; i < end; i++)
			this.put(src[i]);
		return this;
	}

	/**
	 * Relative bulk <i>put</i> method&nbsp;&nbsp;<i>(optional operation)</i>.
	 * 
	 * <p>
	 * This method transfers the entire content of the given source character
	 * array into this buffer. An invocation of this method of the form
	 * <tt>dst.put(a)</tt> behaves in exactly the same way as the invocation
	 * 
	 * <pre>
	 * dst.put(a, 0, a.length)
	 * </pre>
	 * 
	 * @return This buffer
	 * 
	 * @throws BufferOverflowException
	 *             If there is insufficient space in this buffer
	 * 
	 * @throws ReadOnlyBufferException
	 *             If this buffer is read-only
	 */
	public final CharBuffer put(char[] src) {
		return put(src, 0, src.length);
	}

	/**
	 * Relative bulk <i>put</i> method&nbsp;&nbsp;<i>(optional operation)</i>.
	 * 
	 * <p>
	 * This method transfers characters from the given string into this buffer.
	 * If there are more characters to be copied from the string than remain in
	 * this buffer, that is, if <tt>end&nbsp;-&nbsp;start</tt>&nbsp;
	 * <tt>&gt;</tt>&nbsp;<tt>remaining()</tt>, then no characters are
	 * transferred and a {@link BufferOverflowException} is thrown.
	 * 
	 * <p>
	 * Otherwise, this method copies <i>n</i>&nbsp;=&nbsp;<tt>end</tt>
	 * &nbsp;-&nbsp;<tt>start</tt> characters from the given string into this
	 * buffer, starting at the given <tt>start</tt> index and at the current
	 * position of this buffer. The position of this buffer is then incremented
	 * by <i>n</i>.
	 * 
	 * <p>
	 * In other words, an invocation of this method of the form
	 * <tt>dst.put(src,&nbsp;start,&nbsp;end)</tt> has exactly the same effect
	 * as the loop
	 * 
	 * <pre>
	 * for (int i = start; i &lt; end; i++)
	 * 	dst.put(src.charAt(i));
	 * </pre>
	 * 
	 * except that it first checks that there is sufficient space in this buffer
	 * and it is potentially much more efficient.
	 * </p>
	 * 
	 * @param src
	 *            The string from which characters are to be read
	 * 
	 * @param start
	 *            The offset within the string of the first character to be
	 *            read; must be non-negative and no larger than
	 *            <tt>string.length()</tt>
	 * 
	 * @param end
	 *            The offset within the string of the last character to be read,
	 *            plus one; must be non-negative and no larger than
	 *            <tt>string.length()</tt>
	 * 
	 * @return This buffer
	 * 
	 * @throws BufferOverflowException
	 *             If there is insufficient space in this buffer
	 * 
	 * @throws IndexOutOfBoundsException
	 *             If the preconditions on the <tt>start</tt> and <tt>end</tt>
	 *             parameters do not hold
	 * 
	 * @throws ReadOnlyBufferException
	 *             If this buffer is read-only
	 */
	public CharBuffer put(String src, int start, int end) {
		checkBounds(start, end - start, src.length());
		for (int i = start; i < end; i++)
			this.put(src.charAt(i));
		return this;
	}

	/**
	 * Relative bulk <i>put</i> method&nbsp;&nbsp;<i>(optional operation)</i>.
	 * 
	 * <p>
	 * This method transfers the entire content of the given source string into
	 * this buffer. An invocation of this method of the form <tt>dst.put(s)</tt>
	 * behaves in exactly the same way as the invocation
	 * 
	 * <pre>
	 * dst.put(s, 0, s.length())
	 * </pre>
	 * 
	 * @return This buffer
	 * 
	 * @throws BufferOverflowException
	 *             If there is insufficient space in this buffer
	 * 
	 * @throws ReadOnlyBufferException
	 *             If this buffer is read-only
	 */
	public final CharBuffer put(String src) {
		return put(src, 0, src.length());
	}

	// -- Other stuff --

	/**
	 * Tells whether or not this buffer is backed by an accessible character
	 * array.
	 * 
	 * <p>
	 * If this method returns <tt>true</tt> then the {@link #array() array} and
	 * {@link #arrayOffset() arrayOffset} methods may safely be invoked.
	 * </p>
	 * 
	 * @return <tt>true</tt> if, and only if, this buffer is backed by an array
	 *         and is not read-only
	 */
	public final boolean hasArray() {
		return (hb != null) && !isReadOnly;
	}

	/**
	 * Returns the character array that backs this
	 * buffer&nbsp;&nbsp;<i>(optional operation)</i>.
	 * 
	 * <p>
	 * Modifications to this buffer's content will cause the returned array's
	 * content to be modified, and vice versa.
	 * 
	 * <p>
	 * Invoke the {@link #hasArray hasArray} method before invoking this method
	 * in order to ensure that this buffer has an accessible backing array.
	 * </p>
	 * 
	 * @return The array that backs this buffer
	 * 
	 * @throws ReadOnlyBufferException
	 *             If this buffer is backed by an array but is read-only
	 * 
	 * @throws UnsupportedOperationException
	 *             If this buffer is not backed by an accessible array
	 */
	public final char[] array() {
		if (hb == null)
			throw new UnsupportedOperationException();
		if (isReadOnly)
			throw new ReadOnlyBufferException();
		return hb;
	}

	/**
	 * Returns the offset within this buffer's backing array of the first
	 * element of the buffer&nbsp;&nbsp;<i>(optional operation)</i>.
	 * 
	 * <p>
	 * If this buffer is backed by an array then buffer position <i>p</i>
	 * corresponds to array index <i>p</i>&nbsp;+&nbsp;<tt>arrayOffset()</tt>.
	 * 
	 * <p>
	 * Invoke the {@link #hasArray hasArray} method before invoking this method
	 * in order to ensure that this buffer has an accessible backing array.
	 * </p>
	 * 
	 * @return The offset within this buffer's array of the first element of the
	 *         buffer
	 * 
	 * @throws ReadOnlyBufferException
	 *             If this buffer is backed by an array but is read-only
	 * 
	 * @throws UnsupportedOperationException
	 *             If this buffer is not backed by an accessible array
	 */
	public final int arrayOffset() {
		if (hb == null)
			throw new UnsupportedOperationException();
		if (isReadOnly)
			throw new ReadOnlyBufferException();
		return offset;
	}

	/**
	 * Compacts this buffer&nbsp;&nbsp;<i>(optional operation)</i>.
	 * 
	 * <p>
	 * The characters between the buffer's current position and its limit, if
	 * any, are copied to the beginning of the buffer. That is, the character at
	 * index <i>p</i>&nbsp;=&nbsp;<tt>position()</tt> is copied to index zero,
	 * the character at index <i>p</i>&nbsp;+&nbsp;1 is copied to index one, and
	 * so forth until the character at index <tt>limit()</tt>&nbsp;-&nbsp;1 is
	 * copied to index <i>n</i>&nbsp;=&nbsp;<tt>limit()</tt>&nbsp;-&nbsp;
	 * <tt>1</tt>&nbsp;-&nbsp;<i>p</i>. The buffer's position is then set to
	 * <i>n+1</i> and its limit is set to its capacity. The mark, if defined, is
	 * discarded.
	 * 
	 * <p>
	 * The buffer's position is set to the number of characters copied, rather
	 * than to zero, so that an invocation of this method can be followed
	 * immediately by an invocation of another relative <i>put</i> method.
	 * </p>
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * @return This buffer
	 * 
	 * @throws ReadOnlyBufferException
	 *             If this buffer is read-only
	 */
	public abstract CharBuffer compact();

	/**
	 * Tells whether or not this character buffer is direct. </p>
	 * 
	 * @return <tt>true</tt> if, and only if, this buffer is direct
	 */
	public abstract boolean isDirect();

	/**
	 * Returns the current hash code of this buffer.
	 * 
	 * <p>
	 * The hash code of a char buffer depends only upon its remaining elements;
	 * that is, upon the elements from <tt>position()</tt> up to, and including,
	 * the element at <tt>limit()</tt>&nbsp;-&nbsp;<tt>1</tt>.
	 * 
	 * <p>
	 * Because buffer hash codes are content-dependent, it is inadvisable to use
	 * buffers as keys in hash maps or similar data structures unless it is
	 * known that their contents will not change.
	 * </p>
	 * 
	 * @return The current hash code of this buffer
	 */
	public int hashCode() {
		int h = 1;
		int p = position();
		for (int i = limit() - 1; i >= p; i--)
			h = 31 * h + (int) get(i);
		return h;
	}

	/**
	 * Tells whether or not this buffer is equal to another object.
	 * 
	 * <p>
	 * Two char buffers are equal if, and only if,
	 * 
	 * <p>
	 * <ol>
	 * 
	 * <li>
	 * <p>
	 * They have the same element type,
	 * </p>
	 * </li>
	 * 
	 * <li>
	 * <p>
	 * They have the same number of remaining elements, and
	 * </p>
	 * </li>
	 * 
	 * <li>
	 * <p>
	 * The two sequences of remaining elements, considered independently of
	 * their starting positions, are pointwise equal.
	 * </p>
	 * </li>
	 * 
	 * </ol>
	 * 
	 * <p>
	 * A char buffer is not equal to any other type of object.
	 * </p>
	 * 
	 * @param ob
	 *            The object to which this buffer is to be compared
	 * 
	 * @return <tt>true</tt> if, and only if, this buffer is equal to the given
	 *         object
	 */
	public boolean equals(Object ob) {
		if (!(ob instanceof CharBuffer))
			return false;
		CharBuffer that = (CharBuffer) ob;
		if (this.remaining() != that.remaining())
			return false;
		int p = this.position();
		for (int i = this.limit() - 1, j = that.limit() - 1; i >= p; i--, j--) {
			char v1 = this.get(i);
			char v2 = that.get(j);
			if (v1 != v2) {
				if ((v1 != v1) && (v2 != v2)) // For float and double
					continue;
				return false;
			}
		}
		return true;
	}

	/**
	 * Compares this buffer to another.
	 * 
	 * <p>
	 * Two char buffers are compared by comparing their sequences of remaining
	 * elements lexicographically, without regard to the starting position of
	 * each sequence within its corresponding buffer.
	 * 
	 * <p>
	 * A char buffer is not comparable to any other type of object.
	 * 
	 * @return A negative integer, zero, or a positive integer as this buffer is
	 *         less than, equal to, or greater than the given buffer
	 */
	public int compareTo(CharBuffer that) {
		int n = this.position() + Math.min(this.remaining(), that.remaining());
		for (int i = this.position(), j = that.position(); i < n; i++, j++) {
			char v1 = this.get(i);
			char v2 = that.get(j);
			if (v1 == v2)
				continue;
			if ((v1 != v1) && (v2 != v2)) // For float and double
				continue;
			if (v1 < v2)
				return -1;
			return +1;
		}
		return this.remaining() - that.remaining();
	}

	// -- Other char stuff --

	/**
	 * Returns a string containing the characters in this buffer.
	 * 
	 * <p>
	 * The first character of the resulting string will be the character at this
	 * buffer's position, while the last character will be the character at
	 * index <tt>limit()</tt>&nbsp;-&nbsp;1. Invoking this method does not
	 * change the buffer's position.
	 * </p>
	 * 
	 * @return The specified string
	 */
	public String toString() {
		return toString(position(), limit());
	}

	abstract String toString(int start, int end); // package-private

	// --- Methods to support CharSequence ---

	/**
	 * Returns the length of this character buffer.
	 * 
	 * <p>
	 * When viewed as a character sequence, the length of a character buffer is
	 * simply the number of characters between the position (inclusive) and the
	 * limit (exclusive); that is, it is equivalent to <tt>remaining()</tt>.
	 * </p>
	 * 
	 * @return The length of this character buffer
	 */
	public final int length() {
		return remaining();
	}

	/**
	 * Reads the character at the given index relative to the current position.
	 * </p>
	 * 
	 * @param index
	 *            The index of the character to be read, relative to the
	 *            position; must be non-negative and smaller than
	 *            <tt>remaining()</tt>
	 * 
	 * @return The character at index <tt>position()&nbsp;+&nbsp;index</tt>
	 * 
	 * @throws IndexOutOfBoundsException
	 *             If the preconditions on <tt>index</tt> do not hold
	 */
	public final char charAt(int index) {
		return get(position() + checkIndex(index, 1));
	}

	/**
	 * Creates a new character buffer that represents the specified subsequence
	 * of this buffer, relative to the current position.
	 * 
	 * <p>
	 * The new buffer will share this buffer's content; that is, if the content
	 * of this buffer is mutable then modifications to one buffer will cause the
	 * other to be modified. The new buffer's capacity will be that of this
	 * buffer, its position will be <tt>position()</tt>&nbsp;+&nbsp;
	 * <tt>start</tt>, and its limit will be <tt>position()</tt>&nbsp;+&nbsp;
	 * <tt>end</tt>. The new buffer will be direct if, and only if, this buffer
	 * is direct, and it will be read-only if, and only if, this buffer is
	 * read-only.
	 * </p>
	 * 
	 * @param start
	 *            The index, relative to the current position, of the first
	 *            character in the subsequence; must be non-negative and no
	 *            larger than <tt>remaining()</tt>
	 * 
	 * @param end
	 *            The index, relative to the current position, of the character
	 *            following the last character in the subsequence; must be no
	 *            smaller than <tt>start</tt> and no larger than
	 *            <tt>remaining()</tt>
	 * 
	 * @return The new character sequence
	 * 
	 * @throws IndexOutOfBoundsException
	 *             If the preconditions on <tt>start</tt> and <tt>end</tt> do
	 *             not hold
	 */
	public abstract CharSequence subSequence(int start, int end);

	// --- Methods to support Appendable ---

	/**
	 * Appends the specified character sequence to this
	 * buffer&nbsp;&nbsp;<i>(optional operation)</i>.
	 * 
	 * <p>
	 * An invocation of this method of the form <tt>dst.append(csq)</tt> behaves
	 * in exactly the same way as the invocation
	 * 
	 * <pre>
	 * dst.put(csq.toString())
	 * </pre>
	 * 
	 * <p>
	 * Depending on the specification of <tt>toString</tt> for the character
	 * sequence <tt>csq</tt>, the entire sequence may not be appended. For
	 * instance, invoking the {@link CharBuffer#toString() toString} method of a
	 * character buffer will return a subsequence whose content depends upon the
	 * buffer's position and limit.
	 * 
	 * @param csq
	 *            The character sequence to append. If <tt>csq</tt> is
	 *            <tt>null</tt>, then the four characters <tt>"null"</tt> are
	 *            appended to this character buffer.
	 * 
	 * @return This buffer
	 * 
	 * @throws BufferOverflowException
	 *             If there is insufficient space in this buffer
	 * 
	 * @throws ReadOnlyBufferException
	 *             If this buffer is read-only
	 * 
	 * @since 1.5
	 */
	public CharBuffer append(CharSequence csq) {
		if (csq == null)
			return put("null");
		else
			return put(csq.toString());
	}

	/**
	 * Appends a subsequence of the specified character sequence to this
	 * buffer&nbsp;&nbsp;<i>(optional operation)</i>.
	 * 
	 * <p>
	 * An invocation of this method of the form <tt>dst.append(csq, start,
	 * end)</tt> when <tt>csq</tt> is not <tt>null</tt>, behaves in exactly the
	 * same way as the invocation
	 * 
	 * <pre>
	 * dst.put(csq.subSequence(start, end).toString())
	 * </pre>
	 * 
	 * @param csq
	 *            The character sequence from which a subsequence will be
	 *            appended. If <tt>csq</tt> is <tt>null</tt>, then characters
	 *            will be appended as if <tt>csq</tt> contained the four
	 *            characters <tt>"null"</tt>.
	 * 
	 * @return This buffer
	 * 
	 * @throws BufferOverflowException
	 *             If there is insufficient space in this buffer
	 * 
	 * @throws IndexOutOfBoundsException
	 *             If <tt>start</tt> or <tt>end</tt> are negative,
	 *             <tt>start</tt> is greater than <tt>end</tt>, or <tt>end</tt>
	 *             is greater than <tt>csq.length()</tt>
	 * 
	 * @throws ReadOnlyBufferException
	 *             If this buffer is read-only
	 * 
	 * @since 1.5
	 */
	public CharBuffer append(CharSequence csq, int start, int end) {
		CharSequence cs = (csq == null ? "null" : csq);
		return put(cs.subSequence(start, end).toString());
	}

	/**
	 * Appends the specified character to this buffer&nbsp;&nbsp;<i>(optional
	 * operation)</i>.
	 * 
	 * <p>
	 * An invocation of this method of the form <tt>dst.append(c)</tt> behaves
	 * in exactly the same way as the invocation
	 * 
	 * <pre>
	 * dst.put(c)
	 * </pre>
	 * 
	 * @param c
	 *            The 16-bit character to append
	 * 
	 * @return This buffer
	 * 
	 * @throws BufferOverflowException
	 *             If there is insufficient space in this buffer
	 * 
	 * @throws ReadOnlyBufferException
	 *             If this buffer is read-only
	 * 
	 * @since 1.5
	 */
	public CharBuffer append(char c) {
		return put(c);
	}

	// -- Other byte stuff: Access to binary data --

	/**
	 * Retrieves this buffer's byte order.
	 * 
	 * <p>
	 * The byte order of a character buffer created by allocation or by wrapping
	 * an existing <tt>char</tt> array is the {@link ByteOrder#nativeOrder
	 * </code>native order<code>} of the underlying hardware. The byte order of
	 * a character buffer created as a <a href="ByteBuffer.html#views">view</a>
	 * of a byte buffer is that of the byte buffer at the moment that the view
	 * is created.
	 * </p>
	 * 
	 * @return This buffer's byte order
	 */
	public abstract ByteOrder order();

}