java/11 : java.base/java/nio/Buffer.java

Buffer
https://openjdk.java.net/
GPLv2 + Classpath Exception
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * accompanied this code).
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package java.nio;

import jdk.internal.HotSpotIntrinsicCandidate;
import jdk.internal.misc.JavaNioAccess;
import jdk.internal.misc.SharedSecrets;
import jdk.internal.misc.Unsafe;

import java.util.Spliterator;

A container for data of a specific primitive type.
 A buffer is a linear, finite sequence of elements of a specific
primitive type.  Aside from its content, the essential properties of a
buffer are its capacity, limit, and position: 

   A buffer's capacity is the number of elements it contains.  The
  capacity of a buffer is never negative and never changes.  
   A buffer's limit is the index of the first element that should
  not be read or written.  A buffer's limit is never negative and is never
  greater than its capacity.  
   A buffer's position is the index of the next element to be
  read or written.  A buffer's position is never negative and is never
  greater than its limit.  

 There is one subclass of this class for each non-boolean primitive type.
 Transferring data 
 Each subclass of this class defines two categories of get and
put operations: 

   Relative operations read or write one or more elements starting
  at the current position and then increment the position by the number of
  elements transferred.  If the requested transfer exceeds the limit then a
  relative get operation throws a BufferUnderflowException and a relative put operation throws a BufferOverflowException; in either case, no data is transferred. 
   Absolute operations take an explicit element index and do not
  affect the position.  Absolute get and put operations throw an IndexOutOfBoundsException if the index argument exceeds the limit. 

 Data may also, of course, be transferred in to or out of a buffer by the
I/O operations of an appropriate channel, which are always relative to the
current position.
 Marking and resetting 
 A buffer's mark is the index to which its position will be reset when the reset method is invoked. The mark is not always defined, but when it is defined it is never negative and is never greater than the position. If the mark is defined then it is discarded when the position or the limit is adjusted to a value smaller than the mark. If the mark is not defined then invoking the reset method causes an InvalidMarkException to be thrown. 
 Invariants 
 The following invariant holds for the mark, position, limit, and
capacity values:
 0 <= mark <= position <= limit <= capacity

 A newly-created buffer always has a position of zero and a mark that is
undefined.  The initial limit may be zero, or it may be some other value
that depends upon the type of the buffer and the manner in which it is
constructed.  Each element of a newly-allocated buffer is initialized
to zero.
 Additional operations 
 In addition to methods for accessing the position, limit, and capacity
values and for marking and resetting, this class also defines the following
operations upon buffers:

   clear makes a buffer ready for a new sequence of channel-read or relative put operations: It sets the limit to the
  capacity and the position to zero.  
   flip makes a buffer ready for a new sequence of channel-write or relative get operations: It sets the limit to the
  current position and then sets the position to zero.  
   rewind makes a buffer ready for re-reading the data that it already contains: It leaves the limit unchanged and sets the position to zero. 
   slice creates a subsequence of a buffer: It leaves the limit and the position unchanged. 
   duplicate creates a shallow copy of a buffer: It leaves the limit and the position unchanged. 

 Read-only buffers 
 Every buffer is readable, but not every buffer is writable.  The
mutation methods of each buffer class are specified as optional
operations that will throw a ReadOnlyBufferException when invoked upon a read-only buffer. A read-only buffer does not allow its content to be changed, but its mark, position, and limit values are mutable. Whether or not a buffer is read-only may be determined by invoking its isReadOnly method. 
 Thread safety 
 Buffers are not safe for use by multiple concurrent threads.  If a
buffer is to be used by more than one thread then access to the buffer
should be controlled by appropriate synchronization.
 Invocation chaining 
 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; for example, the sequence of statements
b.flip();
b.position(23);
b.limit(42);
can be replaced by the single, more compact statement
b.flip().position(23).limit(42);
Author: Mark Reinhold, JSR-51 Expert Group
Since: 1.4/**
 * A container for data of a specific primitive type.
 *
 * <p> A buffer is a linear, finite sequence of elements of a specific
 * primitive type.  Aside from its content, the essential properties of a
 * buffer are its capacity, limit, and position: </p>
 *
 * <blockquote>
 *
 *   <p> A buffer's <i>capacity</i> is the number of elements it contains.  The
 *   capacity of a buffer is never negative and never changes.  </p>
 *
 *   <p> A buffer's <i>limit</i> is the index of the first element that should
 *   not be read or written.  A buffer's limit is never negative and is never
 *   greater than its capacity.  </p>
 *
 *   <p> A buffer's <i>position</i> is the index of the next element to be
 *   read or written.  A buffer's position is never negative and is never
 *   greater than its limit.  </p>
 *
 * </blockquote>
 *
 * <p> There is one subclass of this class for each non-boolean primitive type.
 *
 *
 * <h2> Transferring data </h2>
 *
 * <p> Each subclass of this class defines two categories of <i>get</i> and
 * <i>put</i> operations: </p>
 *
 * <blockquote>
 *
 *   <p> <i>Relative</i> operations read or write one or more elements starting
 *   at the current position and then increment the position by the number of
 *   elements transferred.  If the requested transfer exceeds the limit then a
 *   relative <i>get</i> operation throws a {@link BufferUnderflowException}
 *   and a relative <i>put</i> operation throws a {@link
 *   BufferOverflowException}; in either case, no data is transferred.  </p>
 *
 *   <p> <i>Absolute</i> operations take an explicit element index and do not
 *   affect the position.  Absolute <i>get</i> and <i>put</i> operations throw
 *   an {@link IndexOutOfBoundsException} if the index argument exceeds the
 *   limit.  </p>
 *
 * </blockquote>
 *
 * <p> Data may also, of course, be transferred in to or out of a buffer by the
 * I/O operations of an appropriate channel, which are always relative to the
 * current position.
 *
 *
 * <h2> Marking and resetting </h2>
 *
 * <p> A buffer's <i>mark</i> is the index to which its position will be reset
 * when the {@link #reset reset} method is invoked.  The mark is not always
 * defined, but when it is defined it is never negative and is never greater
 * than the position.  If the mark is defined then it is discarded when the
 * position or the limit is adjusted to a value smaller than the mark.  If the
 * mark is not defined then invoking the {@link #reset reset} method causes an
 * {@link InvalidMarkException} to be thrown.
 *
 *
 * <h2> Invariants </h2>
 *
 * <p> The following invariant holds for the mark, position, limit, and
 * capacity values:
 *
 * <blockquote>
 *     {@code 0} {@code <=}
 *     <i>mark</i> {@code <=}
 *     <i>position</i> {@code <=}
 *     <i>limit</i> {@code <=}
 *     <i>capacity</i>
 * </blockquote>
 *
 * <p> A newly-created buffer always has a position of zero and a mark that is
 * undefined.  The initial limit may be zero, or it may be some other value
 * that depends upon the type of the buffer and the manner in which it is
 * constructed.  Each element of a newly-allocated buffer is initialized
 * to zero.
 *
 *
 * <h2> Additional operations </h2>
 *
 * <p> In addition to methods for accessing the position, limit, and capacity
 * values and for marking and resetting, this class also defines the following
 * operations upon buffers:
 *
 * <ul>
 *
 *   <li><p> {@link #clear} makes a buffer ready for a new sequence of
 *   channel-read or relative <i>put</i> operations: It sets the limit to the
 *   capacity and the position to zero.  </p></li>
 *
 *   <li><p> {@link #flip} makes a buffer ready for a new sequence of
 *   channel-write or relative <i>get</i> operations: It sets the limit to the
 *   current position and then sets the position to zero.  </p></li>
 *
 *   <li><p> {@link #rewind} makes a buffer ready for re-reading the data that
 *   it already contains: It leaves the limit unchanged and sets the position
 *   to zero.  </p></li>
 *
 *   <li><p> {@link #slice} creates a subsequence of a buffer: It leaves the
 *   limit and the position unchanged. </p></li>
 *
 *   <li><p> {@link #duplicate} creates a shallow copy of a buffer: It leaves
 *   the limit and the position unchanged. </p></li>
 *
 * </ul>
 *
 *
 * <h2> Read-only buffers </h2>
 *
 * <p> Every buffer is readable, but not every buffer is writable.  The
 * mutation methods of each buffer class are specified as <i>optional
 * operations</i> that will throw a {@link ReadOnlyBufferException} when
 * invoked upon a read-only buffer.  A read-only buffer does not allow its
 * content to be changed, but its mark, position, and limit values are mutable.
 * Whether or not a buffer is read-only may be determined by invoking its
 * {@link #isReadOnly isReadOnly} method.
 *
 *
 * <h2> Thread safety </h2>
 *
 * <p> Buffers are not safe for use by multiple concurrent threads.  If a
 * buffer is to be used by more than one thread then access to the buffer
 * should be controlled by appropriate synchronization.
 *
 *
 * <h2> Invocation chaining </h2>
 *
 * <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; for example, the sequence of statements
 *
 * <blockquote><pre>
 * b.flip();
 * b.position(23);
 * b.limit(42);</pre></blockquote>
 *
 * can be replaced by the single, more compact statement
 *
 * <blockquote><pre>
 * b.flip().position(23).limit(42);</pre></blockquote>
 *
 *
 * @author Mark Reinhold
 * @author JSR-51 Expert Group
 * @since 1.4
 */

public abstract class Buffer {
    // Cached unsafe-access object
    static final Unsafe UNSAFE = Unsafe.getUnsafe();

    The characteristics of Spliterators that traverse and split elements
maintained in Buffers.
/**
     * The characteristics of Spliterators that traverse and split elements
     * maintained in Buffers.
     */
    static final int SPLITERATOR_CHARACTERISTICS =
        Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.ORDERED;

    // Invariants: mark <= position <= limit <= capacity
    private int mark = -1;
    private int position = 0;
    private int limit;
    private int capacity;

    // Used by heap byte buffers or direct buffers with Unsafe access
    // For heap byte buffers this field will be the address relative to the
    // array base address and offset into that array. The address might
    // not align on a word boundary for slices, nor align at a long word
    // (8 byte) boundary for byte[] allocations on 32-bit systems.
    // For direct buffers it is the start address of the memory region. The
    // address might not align on a word boundary for slices, nor when created
    // using JNI, see NewDirectByteBuffer(void*, long).
    // Should ideally be declared final
    // NOTE: hoisted here for speed in JNI GetDirectBufferAddress
    long address;

    // Creates a new buffer with the given mark, position, limit, and capacity,
    // after checking invariants.
    //
    Buffer(int mark, int pos, int lim, int cap) {       // package-private
        if (cap < 0)
            throw createCapacityException(cap);
        this.capacity = cap;
        limit(lim);
        position(pos);
        if (mark >= 0) {
            if (mark > pos)
                throw new IllegalArgumentException("mark > position: ("
                                                   + mark + " > " + pos + ")");
            this.mark = mark;
        }
    }

    Returns an IllegalArgumentException indicating that the source and target are the same Buffer. Intended for use in put(src) when the parameter is the Buffer on which the method is being invoked. 
Returns:  IllegalArgumentException
         With a message indicating equal source and target buffers/**
     * Returns an {@code IllegalArgumentException} indicating that the source
     * and target are the same {@code Buffer}.  Intended for use in
     * {@code put(src)} when the parameter is the {@code Buffer} on which the
     * method is being invoked.
     *
     * @return  IllegalArgumentException
     *          With a message indicating equal source and target buffers
     */
    static IllegalArgumentException createSameBufferException() {
        return new IllegalArgumentException("The source buffer is this buffer");
    }

    Verify that the capacity is nonnegative.
Params: capacity – 
        The new buffer's capacity, in $type$s
Throws: IllegalArgumentException –  If the capacity is a negative integer/**
     * Verify that the capacity is nonnegative.
     *
     * @param  capacity
     *         The new buffer's capacity, in $type$s
     *
     * @throws  IllegalArgumentException
     *          If the {@code capacity} is a negative integer
     */
    static IllegalArgumentException createCapacityException(int capacity) {
        assert capacity < 0 : "capacity expected to be negative";
        return new IllegalArgumentException("capacity < 0: ("
            + capacity + " < 0)");
    }

    Returns this buffer's capacity.
Returns:  The capacity of this buffer/**
     * Returns this buffer's capacity.
     *
     * @return  The capacity of this buffer
     */
    public final int capacity() {
        return capacity;
    }

    Returns this buffer's position.
Returns:  The position of this buffer/**
     * Returns this buffer's position.
     *
     * @return  The position of this buffer
     */
    public final int position() {
        return position;
    }

    Sets this buffer's position.  If the mark is defined and larger than the
new position then it is discarded.
Params: newPosition – 
        The new position value; must be non-negative
        and no larger than the current limit
Throws: IllegalArgumentException –  If the preconditions on newPosition do not hold
Returns:  This buffer/**
     * Sets this buffer's position.  If the mark is defined and larger than the
     * new position then it is discarded.
     *
     * @param  newPosition
     *         The new position value; must be non-negative
     *         and no larger than the current limit
     *
     * @return  This buffer
     *
     * @throws  IllegalArgumentException
     *          If the preconditions on {@code newPosition} do not hold
     */
    public Buffer position(int newPosition) {
        if (newPosition > limit | newPosition < 0)
            throw createPositionException(newPosition);
        position = newPosition;
        if (mark > position) mark = -1;
        return this;
    }

    Verify that 0 < newPosition <= limit 
Params: newPosition – 
       The new position value
Throws: IllegalArgumentException – 
        If the specified position is out of bounds./**
     * Verify that {@code 0 < newPosition <= limit}
     *
     * @param newPosition
     *        The new position value
     *
     * @throws IllegalArgumentException
     *         If the specified position is out of bounds.
     */
    private IllegalArgumentException createPositionException(int newPosition) {
        String msg = null;

        if (newPosition > limit) {
            msg = "newPosition > limit: (" + newPosition + " > " + limit + ")";
        } else { // assume negative
            assert newPosition < 0 : "newPosition expected to be negative";
            msg = "newPosition < 0: (" + newPosition + " < 0)";
        }

        return new IllegalArgumentException(msg);
    }

    Returns this buffer's limit.
Returns:  The limit of this buffer/**
     * Returns this buffer's limit.
     *
     * @return  The limit of this buffer
     */
    public final int limit() {
        return limit;
    }

    Sets this buffer's limit.  If the position is larger than the new limit
then it is set to the new limit.  If the mark is defined and larger than
the new limit then it is discarded.
Params: newLimit – 
        The new limit value; must be non-negative
        and no larger than this buffer's capacity
Throws: IllegalArgumentException –  If the preconditions on newLimit do not hold
Returns:  This buffer/**
     * Sets this buffer's limit.  If the position is larger than the new limit
     * then it is set to the new limit.  If the mark is defined and larger than
     * the new limit then it is discarded.
     *
     * @param  newLimit
     *         The new limit value; must be non-negative
     *         and no larger than this buffer's capacity
     *
     * @return  This buffer
     *
     * @throws  IllegalArgumentException
     *          If the preconditions on {@code newLimit} do not hold
     */
    public Buffer limit(int newLimit) {
        if (newLimit > capacity | newLimit < 0)
            throw createLimitException(newLimit);
        limit = newLimit;
        if (position > newLimit) position = newLimit;
        if (mark > newLimit) mark = -1;
        return this;
    }

    Verify that 0 < newLimit <= capacity 
Params: newLimit – 
       The new limit value
Throws: IllegalArgumentException – 
        If the specified limit is out of bounds./**
     * Verify that {@code 0 < newLimit <= capacity}
     *
     * @param newLimit
     *        The new limit value
     *
     * @throws IllegalArgumentException
     *         If the specified limit is out of bounds.
     */
    private IllegalArgumentException createLimitException(int newLimit) {
        String msg = null;

        if (newLimit > capacity) {
            msg = "newLimit > capacity: (" + newLimit + " > " + capacity + ")";
        } else { // assume negative
            assert newLimit < 0 : "newLimit expected to be negative";
            msg = "newLimit < 0: (" + newLimit + " < 0)";
        }

        return new IllegalArgumentException(msg);
    }

    Sets this buffer's mark at its position.
Returns:  This buffer/**
     * Sets this buffer's mark at its position.
     *
     * @return  This buffer
     */
    public Buffer mark() {
        mark = position;
        return this;
    }

    Resets this buffer's position to the previously-marked position.
 Invoking this method neither changes nor discards the mark's
value. 
Throws: InvalidMarkException – 
         If the mark has not been set
Returns:  This buffer/**
     * Resets this buffer's position to the previously-marked position.
     *
     * <p> Invoking this method neither changes nor discards the mark's
     * value. </p>
     *
     * @return  This buffer
     *
     * @throws  InvalidMarkException
     *          If the mark has not been set
     */
    public Buffer reset() {
        int m = mark;
        if (m < 0)
            throw new InvalidMarkException();
        position = m;
        return this;
    }

    Clears this buffer.  The position is set to zero, the limit is set to
the capacity, and the mark is discarded.
 Invoke this method before using a sequence of channel-read or
put operations to fill this buffer.  For example:
buf.clear();     // Prepare buffer for reading
in.read(buf);    // Read data
 This method does not actually erase the data in the buffer, but it
is named as if it did because it will most often be used in situations
in which that might as well be the case. 
Returns:  This buffer/**
     * Clears this buffer.  The position is set to zero, the limit is set to
     * the capacity, and the mark is discarded.
     *
     * <p> Invoke this method before using a sequence of channel-read or
     * <i>put</i> operations to fill this buffer.  For example:
     *
     * <blockquote><pre>
     * buf.clear();     // Prepare buffer for reading
     * in.read(buf);    // Read data</pre></blockquote>
     *
     * <p> This method does not actually erase the data in the buffer, but it
     * is named as if it did because it will most often be used in situations
     * in which that might as well be the case. </p>
     *
     * @return  This buffer
     */
    public Buffer clear() {
        position = 0;
        limit = capacity;
        mark = -1;
        return this;
    }

    Flips this buffer.  The limit is set to the current position and then
the position is set to zero.  If the mark is defined then it is
discarded.
 After a sequence of channel-read or put operations, invoke
this method to prepare for a sequence of channel-write or relative
get operations.  For example:
buf.put(magic);    // Prepend header
in.read(buf);      // Read data into rest of buffer
buf.flip();        // Flip buffer
out.write(buf);    // Write header + data to channel
 This method is often used in conjunction with the compact method when transferring data from one place to another. 
Returns:  This buffer/**
     * Flips this buffer.  The limit is set to the current position and then
     * the position is set to zero.  If the mark is defined then it is
     * discarded.
     *
     * <p> After a sequence of channel-read or <i>put</i> operations, invoke
     * this method to prepare for a sequence of channel-write or relative
     * <i>get</i> operations.  For example:
     *
     * <blockquote><pre>
     * buf.put(magic);    // Prepend header
     * in.read(buf);      // Read data into rest of buffer
     * buf.flip();        // Flip buffer
     * out.write(buf);    // Write header + data to channel</pre></blockquote>
     *
     * <p> This method is often used in conjunction with the {@link
     * java.nio.ByteBuffer#compact compact} method when transferring data from
     * one place to another.  </p>
     *
     * @return  This buffer
     */
    public Buffer flip() {
        limit = position;
        position = 0;
        mark = -1;
        return this;
    }

    Rewinds this buffer.  The position is set to zero and the mark is
discarded.
 Invoke this method before a sequence of channel-write or get
operations, assuming that the limit has already been set
appropriately.  For example:
out.write(buf);    // Write remaining data
buf.rewind();      // Rewind buffer
buf.get(array);    // Copy data into array
Returns:  This buffer/**
     * Rewinds this buffer.  The position is set to zero and the mark is
     * discarded.
     *
     * <p> Invoke this method before a sequence of channel-write or <i>get</i>
     * operations, assuming that the limit has already been set
     * appropriately.  For example:
     *
     * <blockquote><pre>
     * out.write(buf);    // Write remaining data
     * buf.rewind();      // Rewind buffer
     * buf.get(array);    // Copy data into array</pre></blockquote>
     *
     * @return  This buffer
     */
    public Buffer rewind() {
        position = 0;
        mark = -1;
        return this;
    }

    Returns the number of elements between the current position and the
limit.
Returns:  The number of elements remaining in this buffer/**
     * Returns the number of elements between the current position and the
     * limit.
     *
     * @return  The number of elements remaining in this buffer
     */
    public final int remaining() {
        return limit - position;
    }

    Tells whether there are any elements between the current position and
the limit.
Returns:  true if, and only if, there is at least one element remaining in this buffer/**
     * Tells whether there are any elements between the current position and
     * the limit.
     *
     * @return  {@code true} if, and only if, there is at least one element
     *          remaining in this buffer
     */
    public final boolean hasRemaining() {
        return position < limit;
    }

    Tells whether or not this buffer is read-only.
Returns:  true if, and only if, this buffer is read-only/**
     * Tells whether or not this buffer is read-only.
     *
     * @return  {@code true} if, and only if, this buffer is read-only
     */
    public abstract boolean isReadOnly();

    Tells whether or not this buffer is backed by an accessible
array.
 If this method returns true then the array and arrayOffset methods may safely be invoked. 
Returns:  true if, and only if, this buffer is backed by an array and is not read-only
Since: 1.6/**
     * Tells whether or not this buffer is backed by an accessible
     * 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
     *
     * @since 1.6
     */
    public abstract boolean hasArray();

    Returns the array that backs this
buffer  (optional operation).
 This method is intended to allow array-backed buffers to be
passed to native code more efficiently. Concrete subclasses
provide more strongly-typed return values for this method.
 Modifications to this buffer's content will cause the returned
array's content to be modified, and vice versa.
 Invoke the hasArray method before invoking this method in order to ensure that this buffer has an accessible backing array. 
Throws: ReadOnlyBufferException – 
         If this buffer is backed by an array but is read-only
UnsupportedOperationException – 
         If this buffer is not backed by an accessible array
Returns:  The array that backs this buffer
Since: 1.6/**
     * Returns the array that backs this
     * buffer&nbsp;&nbsp;<i>(optional operation)</i>.
     *
     * <p> This method is intended to allow array-backed buffers to be
     * passed to native code more efficiently. Concrete subclasses
     * provide more strongly-typed return values for this method.
     *
     * <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
     *
     * @since 1.6
     */
    public abstract Object array();

    Returns the offset within this buffer's backing array of the first
element of the buffer  (optional operation).
 If this buffer is backed by an array then buffer position p
corresponds to array index p + arrayOffset(). 
 Invoke the hasArray method before invoking this method in order to ensure that this buffer has an accessible backing array. 
Throws: ReadOnlyBufferException – 
         If this buffer is backed by an array but is read-only
UnsupportedOperationException – 
         If this buffer is not backed by an accessible array
Returns:  The offset within this buffer's array
         of the first element of the buffer
Since: 1.6/**
     * 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
     *
     * @since 1.6
     */
    public abstract int arrayOffset();

    Tells whether or not this buffer is
direct.
Returns:  true if, and only if, this buffer is direct
Since: 1.6/**
     * Tells whether or not this buffer is
     * <a href="ByteBuffer.html#direct"><i>direct</i></a>.
     *
     * @return  {@code true} if, and only if, this buffer is direct
     *
     * @since 1.6
     */
    public abstract boolean isDirect();

    Creates a new buffer whose content is a shared subsequence of
this buffer's content.
 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.
 The new buffer's position will be zero, its capacity and its limit
will be the number of elements remaining in this buffer, 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.  
Returns:  The new buffer
Since: 9/**
     * Creates a new 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 elements remaining in this buffer, 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 buffer
     *
     * @since 9
     */
    public abstract Buffer slice();

    Creates a new buffer that shares this buffer's content.
 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.
 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.  
Returns:  The new buffer
Since: 9/**
     * Creates a new 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 buffer
     *
     * @since 9
     */
    public abstract Buffer duplicate();


    // -- Package-private methods for bounds checking, etc. --

    Returns: the base reference, paired with the address
field, which in combination can be used for unsafe access into a heap
buffer or direct byte buffer (and views of)./**
     *
     * @return the base reference, paired with the address
     * field, which in combination can be used for unsafe access into a heap
     * buffer or direct byte buffer (and views of).
     */
    abstract Object base();

    Checks the current position against the limit, throwing a BufferUnderflowException if it is not smaller than the limit, and then increments the position. 
Returns:  The current position value, before it is incremented/**
     * Checks the current position against the limit, throwing a {@link
     * BufferUnderflowException} if it is not smaller than the limit, and then
     * increments the position.
     *
     * @return  The current position value, before it is incremented
     */
    final int nextGetIndex() {                          // package-private
        int p = position;
        if (p >= limit)
            throw new BufferUnderflowException();
        position = p + 1;
        return p;
    }

    final int nextGetIndex(int nb) {                    // package-private
        int p = position;
        if (limit - p < nb)
            throw new BufferUnderflowException();
        position = p + nb;
        return p;
    }

    Checks the current position against the limit, throwing a BufferOverflowException if it is not smaller than the limit, and then increments the position. 
Returns:  The current position value, before it is incremented/**
     * Checks the current position against the limit, throwing a {@link
     * BufferOverflowException} if it is not smaller than the limit, and then
     * increments the position.
     *
     * @return  The current position value, before it is incremented
     */
    final int nextPutIndex() {                          // package-private
        int p = position;
        if (p >= limit)
            throw new BufferOverflowException();
        position = p + 1;
        return p;
    }

    final int nextPutIndex(int nb) {                    // package-private
        int p = position;
        if (limit - p < nb)
            throw new BufferOverflowException();
        position = p + nb;
        return p;
    }

    Checks the given index against the limit, throwing an IndexOutOfBoundsException if it is not smaller than the limit or is smaller than zero. /**
     * Checks the given index against the limit, throwing an {@link
     * IndexOutOfBoundsException} if it is not smaller than the limit
     * or is smaller than zero.
     */
    @HotSpotIntrinsicCandidate
    final int checkIndex(int i) {                       // package-private
        if ((i < 0) || (i >= limit))
            throw new IndexOutOfBoundsException();
        return i;
    }

    final int checkIndex(int i, int nb) {               // package-private
        if ((i < 0) || (nb > limit - i))
            throw new IndexOutOfBoundsException();
        return i;
    }

    final int markValue() {                             // package-private
        return mark;
    }

    final void truncate() {                             // package-private
        mark = -1;
        position = 0;
        limit = 0;
        capacity = 0;
    }

    final void discardMark() {                          // package-private
        mark = -1;
    }

    static void checkBounds(int off, int len, int size) { // package-private
        if ((off | len | (off + len) | (size - (off + len))) < 0)
            throw new IndexOutOfBoundsException();
    }

    static {
        // setup access to this package in SharedSecrets
        SharedSecrets.setJavaNioAccess(
            new JavaNioAccess() {
                @Override
                public JavaNioAccess.BufferPool getDirectBufferPool() {
                    return Bits.BUFFER_POOL;
                }
                @Override
                public ByteBuffer newDirectByteBuffer(long addr, int cap, Object ob) {
                    return new DirectByteBuffer(addr, cap, ob);
                }
                @Override
                public void truncate(Buffer buf) {
                    buf.truncate();
                }
            });
    }

}
Params:	capacity – The new buffer's capacity, in $type$s
Throws:	IllegalArgumentException – If the `capacity` is a negative integer
Params:	newPosition – The new position value; must be non-negative and no larger than the current limit
Throws:	IllegalArgumentException – If the preconditions on `newPosition` do not hold
Returns:	This buffer
Params:	newPosition – The new position value
Throws:	IllegalArgumentException – If the specified position is out of bounds.
Params:	newLimit – The new limit value; must be non-negative and no larger than this buffer's capacity
Throws:	IllegalArgumentException – If the preconditions on `newLimit` do not hold
Returns:	This buffer
Params:	newLimit – The new limit value
Throws:	IllegalArgumentException – If the specified limit is out of bounds.
Throws:	InvalidMarkException – If the mark has not been set
Returns:	This buffer
Returns:	`true` if, and only if, this buffer is backed by an array and is not read-only
Since:	1.6
Throws:	ReadOnlyBufferException – If this buffer is backed by an array but is read-only UnsupportedOperationException – If this buffer is not backed by an accessible array
Returns:	The array that backs this buffer
Since:	1.6
Returns:	`true` if, and only if, this buffer is direct
Since:	1.6
/

java/ 11/ java.base/java/nio/Buffer.java

Transferring data

Marking and resetting

Invariants

Additional operations

Read-only buffers

Thread safety

Invocation chaining
