ReadableByteChannel

ReadableByteChannel

java.nio.channels

---

Java 1.4

closeable

This subinterface of Channel defines a single key read( ) method which reads bytes from the channel and stores them in the specified ByteBuffer , updating the buffer position as it does so. read( ) attempts to read as many bytes as will fit in the specified buffer, (see Buffer.remaining( ) ) but may read fewer than this. If the channel is a nonblocking channel, for example, the read( ) will return immediately, even if there are no bytes available to be read. read( ) returns the number of bytes actually read (which may be zero in the nonblocking case), or returns -1 if there are no more bytes to be read in the channel (if, for example, the end of a file has been reached, or the other end of a socket has been closed.)

read( ) is declared to throw an IOException . More specifically , it may throw a ClosedChannelException if the channel is closed. If the channel is closed asynchronously, or if a blocked thread is interrupted , the read( ) method may terminate with an AsynchronousCloseException or a ClosedByInterruptException . read( ) may also throw an unchecked NonReadableChannelException if it is called on a channel that was not opened or configured to allow reading.

ReadableByteChannel implementations are required to be thread-safe: only one thread may perform a read operation on a channel at a time. If a read operation is in progress, then any call to read( ) will block until the in-progress operation completes. Some channel implementations may allow read and write operations to proceed concurrently, but none will allow two read operations to proceed at the same time.

Figure 13-35. java.nio.channels.ReadableByteChannel

 public interface  ReadableByteChannel  extends Channel {  // Public Instance Methods  int  read  (java.nio.ByteBuffer  dst  ) throws java.io.IOException;   } 

Implementations

ByteChannel , Pipe.SourceChannel , ScatteringByteChannel

Passed To

Channels.{newInputStream( ) , newReader( )} , FileChannel.transferFrom( ) , java.util.Scanner.Scanner( )

Returned By

Channels.newChannel( )