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## java.nio.channels
Interface GatheringByteChannel

All Superinterfaces:
  Channel, WritableByteChannel

All Known Implementing Classes:
  DatagramChannel, FileChannel, Pipe.SinkChannel, SocketChannel

public interface GatheringByteChannel
extends WritableByteChannel

A channel that can write bytes from a sequence of buffers.

A gathering write operation writes, in a single invocation, a sequence of bytes from one or more of a given sequence of buffers. Gathering writes are often useful when implementing network protocols or file formats that, for example, group data into segments consisting of one or more fixed-length headers followed by a variable-length body. Similar scattering read operations are defined in the `ScatteringByteChannel` interface.

Since:
  1.4

Method Summary
`long` | `write(ByteBuffer[] srcs)` Writes a sequence of bytes to this channel from the given buffers.
`long` | `write(ByteBuffer[] srcs, int offset, int length)` Writes a sequence of bytes to this channel from a subsequence of the given buffers.

Methods inherited from interface java.nio.channels.WritableByteChannel
`write`

Methods inherited from interface java.nio.channels.Channel
`close, isOpen`

Method Detail

### write

    public long write(ByteBuffer[] srcs,
                      int offset,
                      int length)
               throws IOException

  Writes a sequence of bytes to this channel from a subsequence of the given buffers.

  An attempt is made to write up to r bytes to this channel, where r is the total number of bytes remaining in the specified subsequence of the given buffer array, that is,

  >      srcs[offset].remaining()
  >          + srcs[offset+1].remaining()
  >          + ... + srcs[offset+length-1].remaining()

  at the moment that this method is invoked.

  Suppose that a byte sequence of length n is written, where `0` `<=` n `<=` r. Up to the first `srcs[offset].remaining()` bytes of this sequence are written from buffer `srcs[offset]`, up to the next `srcs[offset+1].remaining()` bytes are written from buffer `srcs[offset+1]`, and so forth, until the entire byte sequence is written. As many bytes as possible are written from each buffer, hence the final position of each updated buffer, except the last updated buffer, is guaranteed to be equal to that buffer's limit.

  Unless otherwise specified, a write operation will return only after writing all of the r requested bytes. Some types of channels, depending upon their state, may write only some of the bytes or possibly none at all. A socket channel in non-blocking mode, for example, cannot write any more bytes than are free in the socket's output buffer.

  This method may be invoked at any time. If another thread has already initiated a write operation upon this channel, however, then an invocation of this method will block until the first operation is complete.

  Parameters:
    `srcs` - The buffers from which bytes are to be retrieved
    `offset` - The offset within the buffer array of the first buffer from which bytes are to be retrieved; must be non-negative and no larger than `srcs.length`
    `length` - The maximum number of buffers to be accessed; must be non-negative and no larger than `srcs.length` - `offset`
  Returns:
    The number of bytes written, possibly zero
  Throws:
    `IndexOutOfBoundsException` - If the preconditions on the `offset` and `length` parameters do not hold
    `NonWritableChannelException` - If this channel was not opened for writing
    `ClosedChannelException` - If this channel is closed
    `AsynchronousCloseException` - If another thread closes this channel while the write operation is in progress
    `ClosedByInterruptException` - If another thread interrupts the current thread while the write operation is in progress, thereby closing the channel and setting the current thread's interrupt status
    `IOException` - If some other I/O error occurs

### write

    public long write(ByteBuffer[] srcs)
               throws IOException

  Writes a sequence of bytes to this channel from the given buffers.

  An invocation of this method of the form `c.write(srcs)` behaves in exactly the same manner as the invocation

  >      c.write(srcs, 0, srcs.length);

  Parameters:
    `srcs` - The buffers from which bytes are to be retrieved
  Returns:
    The number of bytes written, possibly zero
  Throws:
    `NonWritableChannelException` - If this channel was not opened for writing
    `ClosedChannelException` - If this channel is closed
    `AsynchronousCloseException` - If another thread closes this channel while the write operation is in progress
    `ClosedByInterruptException` - If another thread interrupts the current thread while the write operation is in progress, thereby closing the channel and setting the current thread's interrupt status
    `IOException` - If some other I/O error occurs

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For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2003 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.