android-15.0.0_r3/s

/*
 * Copyright (C) 2014 The Android Open Source Project
 * Copyright (c) 2000, 2021, 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.
 */

// -- This file was mechanically generated: Do not edit! -- //
// Android-note: This file is generated by ojluni/src/tools/gensrc_android.sh.

package java.nio;


import java.io.IOException;

import java.lang.ref.Reference;

import java.util.Spliterator;
import java.util.stream.StreamSupport;
import java.util.stream.IntStream;


import java.util.Objects;
import jdk.internal.misc.Unsafe;
import jdk.internal.util.ArraysSupport;
import libcore.io.Memory;
import dalvik.annotation.codegen.CovariantReturnType;

// Android-changed: Fix that if[byte] isn't processed by the SppTool. Upstream doc has the same bug.
/**
 * A char buffer.
 *
 * <p> This class defines four categories of operations upon
 * char buffers:
 *
 * <ul>
 *
 *   <li><p> Absolute and relative {@link #get() <i>get</i>} and
 *   {@link #put(char) <i>put</i>} methods that read and write
 *   single chars; </p></li>
 *
 *   <li><p> Absolute and relative {@link #get(char[]) <i>bulk get</i>}
 *   methods that transfer contiguous sequences of chars from this buffer
 *   into an array; and</p></li>
 *
 *   <li><p> Absolute and relative {@link #put(char[]) <i>bulk put</i>}
 *   methods that transfer contiguous sequences of chars from a
 *   char array,  string, or some other char
 *   buffer into this buffer; and </p></li>
 *


 *
 *   <li><p> A method for {@link #compact compacting}
 *   a char buffer.  </p></li>
 *
 * </ul>
 *
 * <p> Char buffers can be created either by {@link #allocate
 * <i>allocation</i>}, which allocates space for the buffer's
 *


 *
 * content, by {@link #wrap(char[]) <i>wrapping</i>} an existing
 * char array or string into a buffer, or by creating a
 * <a href="ByteBuffer.html#views"><i>view</i></a> of an existing byte buffer.
 *

 *


*

 *
 * <p> Like a byte buffer, a char buffer is either <a
 * href="ByteBuffer.html#direct"><i>direct</i> or <i>non-direct</i></a>.  A
 * char buffer created via the {@code wrap} methods of this class will
 * be non-direct.  A char buffer created as a view of a byte buffer will
 * be direct if, and only if, the byte buffer itself is direct.  Whether or not
 * a char buffer is direct may be determined by invoking the {@link
 * #isDirect isDirect} method.  </p>
 *

*

 *
 * <p> This class implements the {@link CharSequence} interface so that
 * character buffers may be used wherever character sequences are accepted, for
 * example in the regular-expression package {@link java.util.regex}.
 * The methods defined by {@code CharSequence} operate relative to the current
 * position of the buffer when they are invoked.
 * </p>
 *

 *


 *
 * <p> Methods in this class that do not otherwise have a value to return are
 * specified to return the buffer upon which they are invoked.  This allows
 * method invocations to be chained.
 *


 *
 * The sequence of statements
 *
 * <blockquote><pre>
 * cb.put("text/");
 * cb.put(subtype);
 * cb.put("; charset=");
 * cb.put(enc);</pre></blockquote>
 *
 * can, for example, be replaced by the single statement
 *
 * <blockquote><pre>
 * cb.put("text/").put(subtype).put("; charset=").put(enc);</pre></blockquote>
 *

 *
 *
 * @author Mark Reinhold
 * @author JSR-51 Expert Group
 * @since 1.4
 */

public abstract class CharBuffer
    extends Buffer
    implements Comparable<CharBuffer>, Appendable, CharSequence, Readable
{
    // Cached array base offset
    private static final long ARRAY_BASE_OFFSET = UNSAFE.arrayBaseOffset(char[].class);

    // These fields are declared here rather than in Heap-X-Buffer in order to
    // reduce the number of virtual method invocations needed to access these
    // values, which is especially costly when coding small buffers.
    //
    final char[] hb;                  // Non-null only for heap buffers
    final int offset;
    boolean isReadOnly;

    // Android-added: Added ELEMENT_SIZE_SHIFT for NIOAccess class and @UnsupportedAppUsage.
    private static final int ELEMENT_SIZE_SHIFT = 1;

    // Creates a new buffer with the given mark, position, limit, capacity,
    // backing array, and array offset
    //
    // Android-removed: Removed MemorySegmentProxy to be supported yet./
    CharBuffer(int mark, int pos, int lim, int cap,   // package-private
                 char[] hb, int offset)
    {
        // Android-added: elementSizeShift parameter (log2 of element size).
        super(mark, pos, lim, cap, ELEMENT_SIZE_SHIFT);
        this.hb = hb;
        this.offset = offset;
    }

    // Creates a new buffer with the given mark, position, limit, and capacity
    //
    CharBuffer(int mark, int pos, int lim, int cap) { // package-private
        this(mark, pos, lim, cap, null, 0);
    }

    // Android-removed: Unused constructor.
    /*
    // Creates a new buffer with given base, address and capacity
    //
    CharBuffer(char[] hb, long addr, int cap) { // package-private
        super(addr, cap);
        this.hb = hb;
        this.offset = 0;
    }
    */

    @Override
    Object base() {
        return hb;
    }


    /**
     * Allocates a new char buffer.
     *
     * <p> The new buffer's position will be zero, its limit will be its
     * capacity, its mark will be undefined, each of its elements will be
     * initialized to zero, and its byte order will be


     * the {@link ByteOrder#nativeOrder native order} of the underlying
     * hardware.

     * It will have a {@link #array backing array}, and its
     * {@link #arrayOffset array offset} will be zero.
     *
     * @param  capacity
     *         The new buffer's capacity, in chars
     *
     * @return  The new char buffer
     *
     * @throws  IllegalArgumentException
     *          If the {@code capacity} is a negative integer
     */
    public static CharBuffer allocate(int capacity) {
        if (capacity < 0)
            throw createCapacityException(capacity);
        // Android-removed: Removed MemorySegmentProxy not supported yet.
        return new HeapCharBuffer(capacity, capacity);
    }

    /**
     * Wraps a char array into a buffer.
     *
     * <p> The new buffer will be backed by the given char array;
     * that is, modifications to the buffer will cause the array to be modified
     * and vice versa.  The new buffer's capacity will be
     * {@code array.length}, its position will be {@code offset}, its limit
     * will be {@code offset + length}, its mark will be undefined, and its
     * byte order will be


     * the {@link ByteOrder#nativeOrder native order} of the underlying
     * hardware.

     * Its {@link #array backing array} will be the given array, and
     * its {@link #arrayOffset array offset} will be zero.  </p>
     *
     * @param  array
     *         The array that will back the new buffer
     *
     * @param  offset
     *         The offset of the subarray to be used; must be non-negative and
     *         no larger than {@code array.length}.  The new buffer's position
     *         will be set to this value.
     *
     * @param  length
     *         The length of the subarray to be used;
     *         must be non-negative and no larger than
     *         {@code array.length - offset}.
     *         The new buffer's limit will be set to {@code offset + length}.
     *
     * @return  The new char buffer
     *
     * @throws  IndexOutOfBoundsException
     *          If the preconditions on the {@code offset} and {@code length}
     *          parameters do not hold
     */
    public static CharBuffer wrap(char[] array,
                                    int offset, int length)
    {
        try {
        // Android-removed: Removed MemorySegmentProxy not supported yet.
            return new HeapCharBuffer(array, offset, length);
        } catch (IllegalArgumentException x) {
            throw new IndexOutOfBoundsException();
        }
    }

    /**
     * Wraps a char array into a buffer.
     *
     * <p> The new buffer will be backed by the given char array;
     * that is, modifications to the buffer will cause the array to be modified
     * and vice versa.  The new buffer's capacity and limit will be
     * {@code array.length}, its position will be zero, its mark will be
     * undefined, and its byte order will be


     * the {@link ByteOrder#nativeOrder native order} of the underlying
     * hardware.

     * Its {@link #array backing array} will be the given array, and its
     * {@link #arrayOffset array offset} will be zero.  </p>
     *
     * @param  array
     *         The array that will back this buffer
     *
     * @return  The new char buffer
     */
    public static CharBuffer wrap(char[] array) {
        return wrap(array, 0, array.length);
    }


    /**
     * Attempts to read characters into the specified character buffer.
     * The buffer is used as a repository of characters as-is: the only
     * changes made are the results of a put operation. No flipping or
     * rewinding of the buffer is performed.
     *
     * @param target the buffer to read characters into
     * @return The number of characters added to the buffer, or
     *         -1 if this source of characters is at its end
     * @throws IOException if an I/O error occurs
     * @throws NullPointerException if target is null
     * @throws ReadOnlyBufferException if target is a read only buffer
     * @since 1.5
     */
    public int read(CharBuffer target) throws IOException {
        // Android-added: Android throws NullPointerException.
        Objects.requireNonNull(target);
        // Determine the number of bytes n that can be transferred
        int limit = limit();
        int pos = position();
        int remaining = limit - pos;
        assert remaining >= 0;
        if (remaining <= 0) // include equality condition when remaining == 0
            return -1;

        int targetRemaining = target.remaining();
        assert targetRemaining >= 0;
        if (targetRemaining <= 0) // include condition targetRemaining == 0
            return 0;

        int n = Math.min(remaining, targetRemaining);

        // Set source limit to prevent target overflow
        if (targetRemaining < remaining)
            limit(pos + n);
        try {
            if (n > 0)
                target.put(this);
        } finally {
            limit(limit); // restore real limit
        }
        return n;
    }

    /**
     * Wraps a character sequence into a buffer.
     *
     * <p> The content of the new, read-only buffer will be the content of the
     * given character sequence.  The buffer's capacity will be
     * {@code csq.length()}, its position will be {@code start}, its limit
     * will be {@code end}, and its mark will be undefined.  </p>
     *
     * @param  csq
     *         The character sequence from which the new character buffer is to
     *         be created
     *
     * @param  start
     *         The index of the first character to be used;
     *         must be non-negative and no larger than {@code csq.length()}.
     *         The new buffer's position will be set to this value.
     *
     * @param  end
     *         The index of the character following the last character to be
     *         used; must be no smaller than {@code start} and no larger
     *         than {@code csq.length()}.
     *         The new buffer's limit will be set to this value.
     *
     * @return  The new character buffer
     *
     * @throws  IndexOutOfBoundsException
     *          If the preconditions on the {@code start} and {@code end}
     *          parameters do not hold
     */
    public static CharBuffer wrap(CharSequence csq, int start, int end) {
        try {
            return new StringCharBuffer(csq, start, end);
        } catch (IllegalArgumentException x) {
            throw new IndexOutOfBoundsException();
        }
    }

    /**
     * Wraps a character sequence into a buffer.
     *
     * <p> The content of the new, read-only buffer will be the content of the
     * given character sequence.  The new buffer's capacity and limit will be
     * {@code csq.length()}, its position will be zero, and its mark will be
     * undefined.  </p>
     *
     * @param  csq
     *         The character sequence from which the new character buffer is to
     *         be created
     *
     * @return  The new character buffer
     */
    public static CharBuffer wrap(CharSequence csq) {
        return wrap(csq, 0, csq.length());
    }


    /**
     * Creates a new char 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 chars remaining in this buffer, its mark will be
     * undefined, and its byte order will be


     * identical to that 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 char buffer


     */
    @Override
    public abstract CharBuffer slice();

    /**
     * Creates a new char buffer whose content is a shared subsequence of
     * this buffer's content.
     *
     * <p> The content of the new buffer will start at position {@code index}
     * in this buffer, and will contain {@code length} elements. 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 {@code length}, its mark will be undefined, and its byte order
     * will be


     * identical to that 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>
     *
     * @param   index
     *          The position in this buffer at which the content of the new
     *          buffer will start; must be non-negative and no larger than
     *          {@link #limit() limit()}
     *
     * @param   length
     *          The number of elements the new buffer will contain; must be
     *          non-negative and no larger than {@code limit() - index}
     *
     * @return  The new buffer
     *
     * @throws  IndexOutOfBoundsException
     *          If {@code index} is negative or greater than {@code limit()},
     *          {@code length} is negative, or {@code length > limit() - index}
     *
     * @since 13
     */
    @Override
    public abstract CharBuffer slice(int index, int length);

    /**
     * Creates a new char 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,


     * mark values, and byte order 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 char buffer
     */
    @Override
    public abstract CharBuffer duplicate();

    /**
     * Creates a new, read-only char 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,


     * mark values, and byte order 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 char buffer
     */
    public abstract CharBuffer asReadOnlyBuffer();


    // -- Singleton get/put methods --

    /**
     * Relative <i>get</i> method.  Reads the char at this buffer's
     * current position, and then increments the position.
     *
     * @return  The char 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 char into this buffer at the current
     * position, and then increments the position. </p>
     *
     * @param  c
     *         The char 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 char at the given
     * index.
     *
     * @param  index
     *         The index from which the char will be read
     *
     * @return  The char at the given index
     *
     * @throws  IndexOutOfBoundsException
     *          If {@code index} is negative
     *          or not smaller than the buffer's limit
     */
    public abstract char get(int index);


    /**
     * Absolute <i>get</i> method.  Reads the char at the given
     * index without any validation of the index.
     *
     * @param  index
     *         The index from which the char will be read
     *
     * @return  The char at the given index
     */
    abstract char getUnchecked(int index);   // package-private


    /**
     * Absolute <i>put</i> method&nbsp;&nbsp;<i>(optional operation)</i>.
     *
     * <p> Writes the given char into this buffer at the given
     * index. </p>
     *
     * @param  index
     *         The index at which the char will be written
     *
     * @param  c
     *         The char value to be written
     *
     * @return  This buffer
     *
     * @throws  IndexOutOfBoundsException
     *          If {@code index} 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 chars from this buffer into the given
     * destination array.  If there are fewer chars remaining in the
     * buffer than are required to satisfy the request, that is, if
     * {@code length}&nbsp;{@code >}&nbsp;{@code remaining()}, then no
     * chars are transferred and a {@link BufferUnderflowException} is
     * thrown.
     *
     * <p> Otherwise, this method copies {@code length} chars 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 {@code length}.
     *
     * <p> In other words, an invocation of this method of the form
     * <code>src.get(dst,&nbsp;off,&nbsp;len)</code> has exactly the same effect as
     * the loop
     *
     * <pre>{@code
     *     for (int i = off; i < off + len; i++)
     *         dst[i] = src.get();
     * }</pre>
     *
     * except that it first checks that there are sufficient chars in
     * this buffer and it is potentially much more efficient.
     *
     * @param  dst
     *         The array into which chars are to be written
     *
     * @param  offset
     *         The offset within the array of the first char to be
     *         written; must be non-negative and no larger than
     *         {@code dst.length}
     *
     * @param  length
     *         The maximum number of chars to be written to the given
     *         array; must be non-negative and no larger than
     *         {@code dst.length - offset}
     *
     * @return  This buffer
     *
     * @throws  BufferUnderflowException
     *          If there are fewer than {@code length} chars
     *          remaining in this buffer
     *
     * @throws  IndexOutOfBoundsException
     *          If the preconditions on the {@code offset} and {@code length}
     *          parameters do not hold
     */
    public CharBuffer get(char[] dst, int offset, int length) {
        Objects.checkFromIndexSize(offset, length, dst.length);
        int pos = position();
        if (length > limit() - pos)
            throw new BufferUnderflowException();

        getArray(pos, dst, offset, length);

        position(pos + length);
        return this;
    }

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

    /**
     * Absolute bulk <i>get</i> method.
     *
     * <p> This method transfers {@code length} chars from this
     * buffer into the given array, starting at the given index in this
     * buffer and at the given offset in the array.  The position of this
     * buffer is unchanged.
     *
     * <p> An invocation of this method of the form
     * <code>src.get(index,&nbsp;dst,&nbsp;offset,&nbsp;length)</code>
     * has exactly the same effect as the following loop except that it first
     * checks the consistency of the supplied parameters and it is potentially
     * much more efficient:
     *
     * <pre>{@code
     *     for (int i = offset, j = index; i < offset + length; i++, j++)
     *         dst[i] = src.get(j);
     * }</pre>
     *
     * @param  index
     *         The index in this buffer from which the first char will be
     *         read; must be non-negative and less than {@code limit()}
     *
     * @param  dst
     *         The destination array
     *
     * @param  offset
     *         The offset within the array of the first char to be
     *         written; must be non-negative and less than
     *         {@code dst.length}
     *
     * @param  length
     *         The number of chars to be written to the given array;
     *         must be non-negative and no larger than the smaller of
     *         {@code limit() - index} and {@code dst.length - offset}
     *
     * @return  This buffer
     *
     * @throws  IndexOutOfBoundsException
     *          If the preconditions on the {@code index}, {@code offset}, and
     *          {@code length} parameters do not hold
     *
     * @since 13
     */
    public CharBuffer get(int index, char[] dst, int offset, int length) {
        Objects.checkFromIndexSize(index, length, limit());
        Objects.checkFromIndexSize(offset, length, dst.length);

        getArray(index, dst, offset, length);

        return this;
    }

    /**
     * Absolute bulk <i>get</i> method.
     *
     * <p> This method transfers chars from this buffer into the given
     * destination array.  The position of this buffer is unchanged.  An
     * invocation of this method of the form
     * <code>src.get(index,&nbsp;dst)</code> behaves in exactly the same
     * way as the invocation:
     *
     * <pre>
     *     src.get(index, dst, 0, dst.length) </pre>
     *
     * @param  index
     *         The index in this buffer from which the first char will be
     *         read; must be non-negative and less than {@code limit()}
     *
     * @param  dst
     *         The destination array
     *
     * @return  This buffer
     *
     * @throws  IndexOutOfBoundsException
     *          If {@code index} is negative, not smaller than {@code limit()},
     *          or {@code limit() - index < dst.length}
     *
     * @since 13
     */
    public CharBuffer get(int index, char[] dst) {
        return get(index, dst, 0, dst.length);
    }

    private CharBuffer getArray(int index, char[] dst, int offset, int length) {
        // Android-changed: ScopedMemoryAccess is not yet supported.
        /*
        if (

            isAddressable() &&

            ((long)length << 1) > Bits.JNI_COPY_TO_ARRAY_THRESHOLD) {
            long bufAddr = address + ((long)index << 1);
            long dstOffset =
                ARRAY_BASE_OFFSET + ((long)offset << 1);
            long len = (long)length << 1;

            try {

                if (order() != ByteOrder.nativeOrder())
                    SCOPED_MEMORY_ACCESS.copySwapMemory(
                            scope(), null, base(), bufAddr,
                            dst, dstOffset, len, Character.BYTES);
                else

                    SCOPED_MEMORY_ACCESS.copyMemory(
                            scope(), null, base(), bufAddr,
                            dst, dstOffset, len);
            } finally {
                Reference.reachabilityFence(this);
            }
        } else {
            int end = offset + length;
            for (int i = offset, j = index; i < end; i++, j++) {
                dst[i] = get(j);
            }
        }
        */
        int end = offset + length;
        for (int i = offset, j = index; i < end; i++, j++) {
            dst[i] = get(j);
        }
        return this;
    }

    // -- Bulk put operations --

    /**
     * Relative bulk <i>put</i> method&nbsp;&nbsp;<i>(optional operation)</i>.
     *
     * <p> This method transfers the chars remaining in the given source
     * buffer into this buffer.  If there are more chars remaining in the
     * source buffer than in this buffer, that is, if
     * {@code src.remaining()}&nbsp;{@code >}&nbsp;{@code remaining()},
     * then no chars are transferred and a {@link
     * BufferOverflowException} is thrown.
     *
     * <p> Otherwise, this method copies
     * <i>n</i>&nbsp;=&nbsp;{@code src.remaining()} chars 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
     * {@code dst.put(src)} 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.  If this buffer and
     * the source buffer share the same backing array or memory, then the
     * result will be as if the source elements were first copied to an
     * intermediate location before being written into this buffer.
     *
     * @param  src
     *         The source buffer from which chars 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 chars 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 createSameBufferException();
        if (isReadOnly())
            throw new ReadOnlyBufferException();

        int srcPos = src.position();
        int srcLim = src.limit();
        int srcRem = (srcPos <= srcLim ? srcLim - srcPos : 0);
        int pos = position();
        int lim = limit();
        int rem = (pos <= lim ? lim - pos : 0);

        if (srcRem > rem)
            throw new BufferOverflowException();

        putBuffer(pos, src, srcPos, srcRem);

        position(pos + srcRem);
        src.position(srcPos + srcRem);

        return this;
    }

    /**
     * Absolute bulk <i>put</i> method&nbsp;&nbsp;<i>(optional operation)</i>.
     *
     * <p> This method transfers {@code length} chars into this buffer from
     * the given source buffer, starting at the given {@code offset} in the
     * source buffer and the given {@code index} in this buffer. The positions
     * of both buffers are unchanged.
     *
     * <p> In other words, an invocation of this method of the form
     * <code>dst.put(index,&nbsp;src,&nbsp;offset,&nbsp;length)</code>
     * has exactly the same effect as the loop
     *
     * <pre>{@code
     * for (int i = offset, j = index; i < offset + length; i++, j++)
     *     dst.put(j, src.get(i));
     * }</pre>
     *
     * except that it first checks the consistency of the supplied parameters
     * and it is potentially much more efficient.  If this buffer and
     * the source buffer share the same backing array or memory, then the
     * result will be as if the source elements were first copied to an
     * intermediate location before being written into this buffer.
     *
     * @param index
     *        The index in this buffer at which the first char will be
     *        written; must be non-negative and less than {@code limit()}
     *
     * @param src
     *        The buffer from which chars are to be read
     *
     * @param offset
     *        The index within the source buffer of the first char to be
     *        read; must be non-negative and less than {@code src.limit()}
     *
     * @param length
     *        The number of chars to be read from the given buffer;
     *        must be non-negative and no larger than the smaller of
     *        {@code limit() - index} and {@code src.limit() - offset}
     *
     * @return This buffer
     *
     * @throws IndexOutOfBoundsException
     *         If the preconditions on the {@code index}, {@code offset}, and
     *         {@code length} parameters do not hold
     *
     * @throws ReadOnlyBufferException
     *         If this buffer is read-only
     *
     * @since 16
     */
    public CharBuffer put(int index, CharBuffer src, int offset, int length) {
        Objects.checkFromIndexSize(index, length, limit());
        Objects.checkFromIndexSize(offset, length, src.limit());
        if (isReadOnly())
            throw new ReadOnlyBufferException();

        putBuffer(index, src, offset, length);

        return this;
    }

    void putBuffer(int pos, CharBuffer src, int srcPos, int n) {

        // Android-changed: ScopedMemoryAccess is not yet supported.


        /*
        Object srcBase = src.base();

        if (src.isAddressable()) {


            Object base = base();
            assert base != null || isDirect();

            long srcAddr = src.address + ((long)srcPos << 1);
            long addr = address + ((long)pos << 1);
            long len = (long)n << 1;

            try {

                if (this.order() != src.order())
                    SCOPED_MEMORY_ACCESS.copySwapMemory(
                            src.scope(), scope(), srcBase, srcAddr,
                            base, addr, len, Character.BYTES);
                else

                    SCOPED_MEMORY_ACCESS.copyMemory(
                            src.scope(), scope(), srcBase, srcAddr,
                            base, addr, len);
            } finally {
                Reference.reachabilityFence(src);
                Reference.reachabilityFence(this);
            }

        } else { // src.isAddressable() == false
            assert StringCharBuffer.class.isInstance(src);
            int posMax = pos + n;
            for (int i = pos, j = srcPos; i < posMax; i++, j++)
                put(i, src.get(j));
        }

        */


        if (this.hb != null) {
            if (src.hb != null) {
                System.arraycopy(src.hb, srcPos + src.offset, hb, pos + offset, n);
            } else {
                // this and src don't share the same backed char[].
                src.get(srcPos, this.hb, pos + offset, n);
            }
            return;
        } else if (src.hb != null) {
            // this and src don't share the same backed char[].
            this.put(pos, src.hb, srcPos + src.offset, n);
            return;
        }

        // Slow path using get(int).
        int posMax = pos + n;
        Object thisBase = base();
        // If this buffer and the source buffer share the same backing array or memory, then the
        // result will be as if the source elements were first copied to an intermediate location
        // before being written into this buffer.
        // Instead of copying to an intermediate location, we change the writing order.
        boolean ascendingOrder;
        if (isDirect() && src.isDirect()) {
            // Both src and dst should be ByteBufferAsCharBuffer classes.
            // this.offset and src.offset should be zero, and can be ignored.
            long dstStart = this.address + ((long) pos << 1);
            long srcStart = src.address + ((long) srcPos << 1);
            // The second condition is optional, but the ascending order is the preferred behavior.
            ascendingOrder = (dstStart <= srcStart) || (srcStart + ((long) n << 1) < dstStart);
            // We may just do memmove here if both buffer uses the same byte order.
        } else if (thisBase != null && thisBase == src.base()) { // Share the same char[] or byte[]
            if (thisBase == this.hb) { // Both this and src should be HeapCharBuffer
                int dstStart = this.offset + pos;
                int srcStart = src.offset + srcPos;
                ascendingOrder = (dstStart <= srcStart) || (srcStart + n < dstStart);
            } else if (this instanceof ByteBufferAsCharBuffer asDst &&
                src instanceof ByteBufferAsCharBuffer asSrc && thisBase instanceof byte[]) {
                // this.offset and src.offset should be zero, and can be ignored.
                long dstStart = asDst.byteOffset + asDst.bb.offset + ((long) pos << 1);
                long srcStart = asSrc.byteOffset + asSrc.bb.offset + ((long) srcPos << 1);
                ascendingOrder = (dstStart <= srcStart) || (srcStart + ((long) n << 1) < dstStart);
            } else {
                // There isn't a known case following into this condition. We should add a DCHECK here.
                ascendingOrder = true;
            }
        } else {
            ascendingOrder = true;
        }
        if (ascendingOrder) {
            for (int i = pos, j = srcPos; i < posMax; i++, j++) {
                put(i, src.get(j));
            }
        } else {
            for (int i = posMax - 1, j = srcPos + n - 1; i >= pos; i--, j--) {
                put(i, src.get(j));
            }
        }


    }

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

        putArray(pos, src, offset, length);

        position(pos + length);
        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
     * char array into this buffer.  An invocation of this method of the
     * form {@code dst.put(a)} behaves in exactly the same way as the
     * invocation
     *
     * <pre>
     *     dst.put(a, 0, a.length) </pre>
     *
     * @param   src
     *          The source array
     *
     * @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);
    }

    /**
     * Absolute bulk <i>put</i> method&nbsp;&nbsp;<i>(optional operation)</i>.
     *
     * <p> This method transfers {@code length} chars from the given
     * array, starting at the given offset in the array and at the given index
     * in this buffer.  The position of this buffer is unchanged.
     *
     * <p> An invocation of this method of the form
     * <code>dst.put(index,&nbsp;src,&nbsp;offset,&nbsp;length)</code>
     * has exactly the same effect as the following loop except that it first
     * checks the consistency of the supplied parameters and it is potentially
     * much more efficient:
     *
     * <pre>{@code
     *     for (int i = offset, j = index; i < offset + length; i++, j++)
     *         dst.put(j, src[i]);
     * }</pre>
     *
     * @param  index
     *         The index in this buffer at which the first char will be
     *         written; must be non-negative and less than {@code limit()}
     *
     * @param  src
     *         The array from which chars are to be read
     *
     * @param  offset
     *         The offset within the array of the first char to be read;
     *         must be non-negative and less than {@code src.length}
     *
     * @param  length
     *         The number of chars to be read from the given array;
     *         must be non-negative and no larger than the smaller of
     *         {@code limit() - index} and {@code src.length - offset}
     *
     * @return  This buffer
     *
     * @throws  IndexOutOfBoundsException
     *          If the preconditions on the {@code index}, {@code offset}, and
     *          {@code length} parameters do not hold
     *
     * @throws  ReadOnlyBufferException
     *          If this buffer is read-only
     *
     * @since 13
     */
    public CharBuffer put(int index, char[] src, int offset, int length) {
        if (isReadOnly())
            throw new ReadOnlyBufferException();
        Objects.checkFromIndexSize(index, length, limit());
        Objects.checkFromIndexSize(offset, length, src.length);

        putArray(index, src, offset, length);

        return this;
    }

    /**
     * Absolute bulk <i>put</i> method&nbsp;&nbsp;<i>(optional operation)</i>.
     *
     * <p> This method copies chars into this buffer from the given source
     * array.  The position of this buffer is unchanged.  An invocation of this
     * method of the form <code>dst.put(index,&nbsp;src)</code>
     * behaves in exactly the same way as the invocation:
     *
     * <pre>
     *     dst.put(index, src, 0, src.length); </pre>
     *
     * @param  index
     *         The index in this buffer at which the first char will be
     *         written; must be non-negative and less than {@code limit()}
     *
     * @param  src
     *         The array from which chars are to be read
     *
     * @return  This buffer
     *
     * @throws  IndexOutOfBoundsException
     *          If {@code index} is negative, not smaller than {@code limit()},
     *          or {@code limit() - index < src.length}
     *
     * @throws  ReadOnlyBufferException
     *          If this buffer is read-only
     *
     * @since 13
     */
    public CharBuffer put(int index, char[] src) {
        return put(index, src, 0, src.length);
    }

    private CharBuffer putArray(int index, char[] src, int offset, int length) {

        // Android-changed: ScopedMemoryAccess is not yet supported.
        /*
        if (

            isAddressable() &&

            ((long)length << 1) > Bits.JNI_COPY_FROM_ARRAY_THRESHOLD) {
            long bufAddr = address + ((long)index << 1);
            long srcOffset =
                ARRAY_BASE_OFFSET + ((long)offset << 1);
            long len = (long)length << 1;

            try {

                if (order() != ByteOrder.nativeOrder())
                    SCOPED_MEMORY_ACCESS.copySwapMemory(
                            null, scope(), src, srcOffset,
                            base(), bufAddr, len, Character.BYTES);
                else

                    SCOPED_MEMORY_ACCESS.copyMemory(
                            null, scope(), src, srcOffset,
                            base(), bufAddr, len);
            } finally {
                Reference.reachabilityFence(this);
            }
        } else {
            int end = offset + length;
            for (int i = offset, j = index; i < end; i++, j++)
                this.put(j, src[i]);
        }
        */
        int end = offset + length;
        for (int i = offset, j = index; i < end; i++, j++) {
            this.put(j, src[i]);
        }
        return this;


    }


    /**
     * Relative bulk <i>put</i> method&nbsp;&nbsp;<i>(optional operation)</i>.
     *
     * <p> This method transfers chars from the given string into this
     * buffer.  If there are more chars to be copied from the string than
     * remain in this buffer, that is, if
     * <code>end&nbsp;-&nbsp;start</code>&nbsp;{@code >}&nbsp;{@code remaining()},
     * then no chars are transferred and a {@link
     * BufferOverflowException} is thrown.
     *
     * <p> Otherwise, this method copies
     * <i>n</i>&nbsp;=&nbsp;{@code end}&nbsp;-&nbsp;{@code start} chars
     * from the given string into this buffer, starting at the given
     * {@code start} 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
     * <code>dst.put(src,&nbsp;start,&nbsp;end)</code> has exactly the same effect
     * as the loop
     *
     * <pre>{@code
     *     for (int i = start; i < 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.
     *
     * @param  src
     *         The string from which chars are to be read
     *
     * @param  start
     *         The offset within the string of the first char to be read;
     *         must be non-negative and no larger than
     *         {@code string.length()}
     *
     * @param  end
     *         The offset within the string of the last char to be read,
     *         plus one; must be non-negative and no larger than
     *         {@code string.length()}
     *
     * @return  This buffer
     *
     * @throws  BufferOverflowException
     *          If there is insufficient space in this buffer
     *
     * @throws  IndexOutOfBoundsException
     *          If the preconditions on the {@code start} and {@code end}
     *          parameters do not hold
     *
     * @throws  ReadOnlyBufferException
     *          If this buffer is read-only
     */
    public CharBuffer put(String src, int start, int end) {
        Objects.checkFromIndexSize(start, end - start, src.length());

        // BEGIN Android-added: Don't check readonly/overflow if there's nothing to write.
        // This is questionable behaviour but code expects it.
        if (start == end) {
            return this;
        }
        // END Android-added: Don't check readonly/overflow if there's nothing to write.

        if (isReadOnly())
            throw new ReadOnlyBufferException();
        if (end - start > remaining())
            throw new BufferOverflowException();
        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
     * {@code dst.put(s)} behaves in exactly the same way as the invocation
     *
     * <pre>
     *     dst.put(s, 0, s.length()) </pre>
     *
     * @param   src
     *          The source string
     *
     * @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 char
     * array.
     *
     * <p> If this method returns {@code true} then the {@link #array() array}
     * and {@link #arrayOffset() arrayOffset} methods may safely be invoked.
     * </p>
     *
     * @return  {@code true} 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 char 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;{@code arrayOffset()}.
     *
     * <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;
    }

    // -- Covariant return type overrides

    // BEGIN Android-added: covariant overloads of *Buffer methods that return this.
    /**
     * {@inheritDoc}
     */
    // Android-changed: Un-final the method until confirmation of causing no app compat.
    @CovariantReturnType(returnType = CharBuffer.class, presentAfter = 28)
    @Override
    public
    Buffer position(int newPosition) {
        super.position(newPosition);
        return this;
    }

    /**
     * {@inheritDoc}
     */
    // Android-changed: Un-final the method until confirmation of causing no app compat.
    @CovariantReturnType(returnType = CharBuffer.class, presentAfter = 28)
    @Override
    public
    Buffer limit(int newLimit) {
        super.limit(newLimit);
        return this;
    }

    /**
     * {@inheritDoc}
     */
    // Android-changed: Un-final the method until confirmation of causing no app compat.
    @Override
    @CovariantReturnType(returnType = CharBuffer.class, presentAfter = 28)
    public
    Buffer mark() {
        super.mark();
        return this;
    }

    /**
     * {@inheritDoc}
     */
    // Android-changed: Un-final the method until confirmation of causing no app compat.
    @CovariantReturnType(returnType = CharBuffer.class, presentAfter = 28)
    @Override
    public
    Buffer reset() {
        super.reset();
        return this;
    }

    /**
     * {@inheritDoc}
     */
    // Android-changed: Un-final the method until confirmation of causing no app compat.
    @CovariantReturnType(returnType = CharBuffer.class, presentAfter = 28)
    @Override
    public
    Buffer clear() {
        super.clear();
        return this;
    }

    /**
     * {@inheritDoc}
     */
    // Android-changed: Un-final the method until confirmation of causing no app compat.
    @CovariantReturnType(returnType = CharBuffer.class, presentAfter = 28)
    @Override
    public
    Buffer flip() {
        super.flip();
        return this;
    }

    /**
     * {@inheritDoc}
     */
    // Android-changed: Un-final the method until confirmation of causing no app compat.
    @Override
    @CovariantReturnType(returnType = CharBuffer.class, presentAfter = 28)
    public
    Buffer rewind() {
        super.rewind();
        return this;
    }
    // END Android-added: covariant overloads of *Buffer methods that return this.

    /**
     * Compacts this buffer&nbsp;&nbsp;<i>(optional operation)</i>.
     *
     * <p> The chars between the buffer's current position and its limit,
     * if any, are copied to the beginning of the buffer.  That is, the
     * char at index <i>p</i>&nbsp;=&nbsp;{@code position()} is copied
     * to index zero, the char at index <i>p</i>&nbsp;+&nbsp;1 is copied
     * to index one, and so forth until the char at index
     * {@code limit()}&nbsp;-&nbsp;1 is copied to index
     * <i>n</i>&nbsp;=&nbsp;{@code limit()}&nbsp;-&nbsp;{@code 1}&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 chars 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 char buffer is direct.
     *
     * @return  {@code true} if, and only if, this buffer is direct
     */
    public abstract boolean isDirect();


    /**
     * Tells whether this buffer has addressable memory, e.g., a Java array or
     * a native address.  This method returns {@code true}.  Subclasses such as
     * {@code StringCharBuffer}, which wraps a {@code CharSequence}, should
     * override this method to return {@code false}.
     *
     * @return {@code true} if, and only, this buffer has addressable memory
     */
    boolean isAddressable() {
        return true;
    }


    /**
     * 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 {@code position()} up to, and
     * including, the element at {@code limit()}&nbsp;-&nbsp;{@code 1}.
     *
     * <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,
     *
     * <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  {@code true} if, and only if, this buffer is equal to the
     *           given object
     */
    public boolean equals(Object ob) {
        if (this == ob)
            return true;
        if (!(ob instanceof CharBuffer))
            return false;
        CharBuffer that = (CharBuffer)ob;
        int thisPos = this.position();
        int thisRem = this.limit() - thisPos;
        int thatPos = that.position();
        int thatRem = that.limit() - thatPos;
        if (thisRem < 0 || thisRem != thatRem)
            return false;
        return BufferMismatch.mismatch(this, thisPos,
                                       that, thatPos,
                                       thisRem) < 0;
    }

    /**
     * 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.


     * Pairs of {@code char} elements are compared as if by invoking
     * {@link Character#compare(char,char)}.

     *
     * <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 thisPos = this.position();
        int thisRem = this.limit() - thisPos;
        int thatPos = that.position();
        int thatRem = that.limit() - thatPos;
        int length = Math.min(thisRem, thatRem);
        if (length < 0)
            return -1;
        int i = BufferMismatch.mismatch(this, thisPos,
                                        that, thatPos,
                                        length);
        if (i >= 0) {
            return compare(this.get(thisPos + i), that.get(thatPos + i));
        }
        return thisRem - thatRem;
    }

    private static int compare(char x, char y) {


        return Character.compare(x, y);

    }

    /**
     * Finds and returns the relative index of the first mismatch between this
     * buffer and a given buffer.  The index is relative to the
     * {@link #position() position} of each buffer and will be in the range of
     * 0 (inclusive) up to the smaller of the {@link #remaining() remaining}
     * elements in each buffer (exclusive).
     *
     * <p> If the two buffers share a common prefix then the returned index is
     * the length of the common prefix and it follows that there is a mismatch
     * between the two buffers at that index within the respective buffers.
     * If one buffer is a proper prefix of the other then the returned index is
     * the smaller of the remaining elements in each buffer, and it follows that
     * the index is only valid for the buffer with the larger number of
     * remaining elements.
     * Otherwise, there is no mismatch.
     *
     * @param  that
     *         The byte buffer to be tested for a mismatch with this buffer
     *
     * @return  The relative index of the first mismatch between this and the
     *          given buffer, otherwise -1 if no mismatch.
     *
     * @since 11
     */
    public int mismatch(CharBuffer that) {
        int thisPos = this.position();
        int thisRem = this.limit() - thisPos;
        int thatPos = that.position();
        int thatRem = that.limit() - thatPos;
        int length = Math.min(thisRem, thatRem);
        if (length < 0)
            return -1;
        int r = BufferMismatch.mismatch(this, thisPos,
                                        that, thatPos,
                                        length);
        return (r == -1 && thisRem != thatRem) ? length : r;
    }

    // -- 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 {@code limit()}&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
     * {@code remaining()}. </p>
     *
     * @return  The length of this character buffer
     */
    public final int length() {
        return remaining();
    }

    /**
     * Returns {@code true} if this character buffer is empty.
     *
     * @return {@code true} if there are {@code 0} remaining characters,
     *         otherwise {@code false}
     *
     * @since 15
     */
    public final boolean isEmpty() {
        return remaining() == 0;
    }

    /**
     * Reads the character at the given index relative to the current
     * position.
     *
     * @param  index
     *         The index of the character to be read, relative to the position;
     *         must be non-negative and smaller than {@code remaining()}
     *
     * @return  The character at index
     *          <code>position()&nbsp;+&nbsp;index</code>
     *
     * @throws  IndexOutOfBoundsException
     *          If the preconditions on {@code index} 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
     * {@code position()}&nbsp;+&nbsp;{@code start}, its limit will be
     * {@code position()}&nbsp;+&nbsp;{@code end}, and its byte order
     * will be identical to that 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>
     *
     * @param  start
     *         The index, relative to the current position, of the first
     *         character in the subsequence; must be non-negative and no larger
     *         than {@code remaining()}
     *
     * @param  end
     *         The index, relative to the current position, of the character
     *         following the last character in the subsequence; must be no
     *         smaller than {@code start} and no larger than
     *         {@code remaining()}
     *
     * @return  The new character buffer
     *
     * @throws  IndexOutOfBoundsException
     *          If the preconditions on {@code start} and {@code end}
     *          do not hold
     */
    public abstract CharBuffer 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 {@code dst.append(csq)}
     * behaves in exactly the same way as the invocation
     *
     * <pre>
     *     dst.put(csq.toString()) </pre>
     *
     * <p> Depending on the specification of {@code toString} for the
     * character sequence {@code csq}, 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 {@code csq} is
     *         {@code null}, then the four characters {@code "null"} 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 {@code dst.append(csq, start,
     * end)} when {@code csq} is not {@code null}, 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 {@code csq} is {@code null}, then characters
     *         will be appended as if {@code csq} contained the four
     *         characters {@code "null"}.
     *
     * @return  This buffer
     *
     * @throws  BufferOverflowException
     *          If there is insufficient space in this buffer
     *
     * @throws  IndexOutOfBoundsException
     *          If {@code start} or {@code end} are negative, {@code start}
     *          is greater than {@code end}, or {@code end} is greater than
     *          {@code csq.length()}
     *
     * @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 char  to this
     * buffer&nbsp;&nbsp;<i>(optional operation)</i>.
     *
     * <p> An invocation of this method of the form {@code dst.append(c)}
     * behaves in exactly the same way as the invocation
     *
     * <pre>
     *     dst.put(c) </pre>
     *
     * @param  c
     *         The 16-bit char 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 char buffer created by allocation or by
     * wrapping an existing {@code char} array is the {@link
     * ByteOrder#nativeOrder native order} of the underlying
     * hardware.  The byte order of a char 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();


    // The order or null if the buffer does not cover a memory region,
    // such as StringCharBuffer
    abstract ByteOrder charRegionOrder();


    @Override

    public IntStream chars() {
        return StreamSupport.intStream(() -> new CharBufferSpliterator(this),
            Buffer.SPLITERATOR_CHARACTERISTICS, false);
    }


}