Interface SeekableByteChannel
- All Superinterfaces:
- AutoCloseable,- ByteChannel,- Channel,- Closeable,- ReadableByteChannel,- WritableByteChannel
- All Known Implementing Classes:
- FileChannel
 A seekable byte channel is connected to an entity, typically a file,
 that contains a variable-length sequence of bytes that can be read and
 written. The current position can be queried and
 modified. The channel also provides access to
 the current size of the entity to which the channel is connected. The
 size increases when bytes are written beyond its current size; the size
 decreases when it is truncated.
 
 The position and truncate methods
 which do not otherwise have a value to return are specified to return the
 channel upon which they are invoked. This allows method invocations to be
 chained. Implementations of this interface should specialize the return type
 so that method invocations on the implementation class can be chained.
- Since:
- 1.7
- See Also:
- 
Method SummaryModifier and TypeMethodDescriptionlongposition()Returns this channel's position.position(long newPosition) Sets this channel's position.intread(ByteBuffer dst) Reads a sequence of bytes from this channel into the given buffer.longsize()Returns the current size of entity to which this channel is connected.truncate(long size) Truncates the entity, to which this channel is connected, to the given size.intwrite(ByteBuffer src) Writes a sequence of bytes to this channel from the given buffer.
- 
Method Details- 
readReads a sequence of bytes from this channel into the given buffer.Bytes are read starting at this channel's current position, and then the position is updated with the number of bytes actually read. Otherwise this method behaves exactly as specified in the ReadableByteChannelinterface.- Specified by:
- readin interface- ReadableByteChannel
- Parameters:
- dst- The buffer into which bytes are to be transferred
- Returns:
- The number of bytes read, possibly zero, or -1if the channel has reached end-of-stream
- Throws:
- ClosedChannelException- If this channel is closed
- AsynchronousCloseException- If another thread closes this channel while the read operation is in progress
- ClosedByInterruptException- If another thread interrupts the current thread while the read operation is in progress, thereby closing the channel and setting the current thread's interrupt status
- NonReadableChannelException- If this channel was not opened for reading
- IOException- If some other I/O error occurs
 
- 
writeWrites a sequence of bytes to this channel from the given buffer.Bytes are written starting at this channel's current position, unless the channel is connected to an entity such as a file that is opened with the APPENDoption, in which case the position is first advanced to the end. The entity to which the channel is connected is grown, if necessary, to accommodate the written bytes, and then the position is updated with the number of bytes actually written. Otherwise this method behaves exactly as specified by theWritableByteChannelinterface.- Specified by:
- writein interface- WritableByteChannel
- Parameters:
- src- The buffer from which bytes are to be retrieved
- Returns:
- The number of bytes written, possibly zero
- Throws:
- 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
- NonWritableChannelException- If this channel was not opened for writing
- IOException- If some other I/O error occurs
 
- 
positionReturns this channel's position.- Returns:
- This channel's position, a non-negative integer counting the number of bytes from the beginning of the entity to the current position
- Throws:
- ClosedChannelException- If this channel is closed
- IOException- If some other I/O error occurs
 
- 
positionSets this channel's position.Setting the position to a value that is greater than the current size is legal but does not change the size of the entity. A later attempt to read bytes at such a position will immediately return an end-of-file indication. A later attempt to write bytes at such a position will cause the entity to grow to accommodate the new bytes; the values of any bytes between the previous end-of-file and the newly-written bytes are unspecified. Setting the channel's position is not recommended when connected to an entity, typically a file, that is opened with the APPENDoption. When opened for append, the position is first advanced to the end before writing.- Parameters:
- newPosition- The new position, a non-negative integer counting the number of bytes from the beginning of the entity
- Returns:
- This channel
- Throws:
- ClosedChannelException- If this channel is closed
- IllegalArgumentException- If the new position is negative
- IOException- If some other I/O error occurs
 
- 
sizeReturns the current size of entity to which this channel is connected.- Returns:
- The current size, measured in bytes
- Throws:
- ClosedChannelException- If this channel is closed
- IOException- If some other I/O error occurs
 
- 
truncateTruncates the entity, to which this channel is connected, to the given size.If the given size is less than the current size then the entity is truncated, discarding any bytes beyond the new end. If the given size is greater than or equal to the current size then the entity is not modified. In either case, if the current position is greater than the given size then it is set to that size. An implementation of this interface may prohibit truncation when connected to an entity, typically a file, opened with the APPENDoption.- Parameters:
- size- The new size, a non-negative byte count
- Returns:
- This channel
- Throws:
- NonWritableChannelException- If this channel was not opened for writing
- ClosedChannelException- If this channel is closed
- IllegalArgumentException- If the new size is negative
- IOException- If some other I/O error occurs
 
 
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