File	Doc	Category	Size	Date	Package
SelectionKey.java	API Doc	Java SE 5 API	14375	Fri Aug 26 14:57:10 BST 2005	java.nio.channels

SelectionKey

• java.lang.Object

Fields Summary
public static final int	OP_READ Operation-set bit for read operations. Suppose that a selection key's interest set contains OP_READ at the start of a selection operation. If the selector detects that the corresponding channel is ready for reading, has reached end-of-stream, has been remotely shut down for further reading, or has an error pending, then it will add OP_READ to the key's ready-operation set and add the key to its selected-key set.
public static final int	OP_WRITE Operation-set bit for write operations. Suppose that a selection key's interest set contains OP_WRITE at the start of a selection operation. If the selector detects that the corresponding channel is ready for writing, has been remotely shut down for further writing, or has an error pending, then it will add OP_WRITE to the key's ready set and add the key to its selected-key set.
public static final int	OP_CONNECT Operation-set bit for socket-connect operations. Suppose that a selection key's interest set contains OP_CONNECT at the start of a selection operation. If the selector detects that the corresponding socket channel is ready to complete its connection sequence, or has an error pending, then it will add OP_CONNECT to the key's ready set and add the key to its selected-key set.
public static final int	OP_ACCEPT Operation-set bit for socket-accept operations. Suppose that a selection key's interest set contains OP_ACCEPT at the start of a selection operation. If the selector detects that the corresponding server-socket channel is ready to accept another connection, or has an error pending, then it will add OP_ACCEPT to the key's ready set and add the key to its selected-key set.
private volatile Object	attachment

Constructors Summary
protected SelectionKey() Constructs an instance of this class.

Methods Summary
public final java.lang.Object	attach(java.lang.Object ob) Attaches the given object to this key. An attached object may later be retrieved via the {@link #attachment attachment} method. Only one object may be attached at a time; invoking this method causes any previous attachment to be discarded. The current attachment may be discarded by attaching null. param ob The object to be attached; may be null return The previously-attached object, if any, otherwise null Object a = attachment; attachment = ob; return a;
public final java.lang.Object	attachment() Retrieves the current attachment. return The object currently attached to this key, or null if there is no attachment return attachment;
public abstract void	cancel() Requests that the registration of this key's channel with its selector be cancelled. Upon return the key will be invalid and will have been added to its selector's cancelled-key set. The key will be removed from all of the selector's key sets during the next selection operation. If this key has already been cancelled then invoking this method has no effect. Once cancelled, a key remains forever invalid. This method may be invoked at any time. It synchronizes on the selector's cancelled-key set, and therefore may block briefly if invoked concurrently with a cancellation or selection operation involving the same selector.
public abstract java.nio.channels.SelectableChannel	channel() Returns the channel for which this key was created. This method will continue to return the channel even after the key is cancelled. return This key's channel
public abstract int	interestOps() Retrieves this key's interest set. It is guaranteed that the returned set will only contain operation bits that are valid for this key's channel. This method may be invoked at any time. Whether or not it blocks, and for how long, is implementation-dependent. return This key's interest set throws CancelledKeyException If this key has been cancelled
public abstract java.nio.channels.SelectionKey	interestOps(int ops) Sets this key's interest set to the given value. This method may be invoked at any time. Whether or not it blocks, and for how long, is implementation-dependent. param ops The new interest set return This selection key throws IllegalArgumentException If a bit in the set does not correspond to an operation that is supported by this key's channel, that is, if set & ~(channel().validOps()) != 0 throws CancelledKeyException If this key has been cancelled
public final boolean	isAcceptable() Tests whether this key's channel is ready to accept a new socket connection. An invocation of this method of the form k.isAcceptable() behaves in exactly the same way as the expression k.readyOps() & OP_ACCEPT != 0 If this key's channel does not support socket-accept operations then this method always returns false. return true if, and only if, readyOps() & OP_ACCEPT is nonzero throws CancelledKeyException If this key has been cancelled return (readyOps() & OP_ACCEPT) != 0;
public final boolean	isConnectable() Tests whether this key's channel has either finished, or failed to finish, its socket-connection operation. An invocation of this method of the form k.isConnectable() behaves in exactly the same way as the expression k.readyOps() & OP_CONNECT != 0 If this key's channel does not support socket-connect operations then this method always returns false. return true if, and only if, readyOps() & OP_CONNECT is nonzero throws CancelledKeyException If this key has been cancelled return (readyOps() & OP_CONNECT) != 0;
public final boolean	isReadable() Tests whether this key's channel is ready for reading. An invocation of this method of the form k.isReadable() behaves in exactly the same way as the expression k.readyOps() & OP_READ != 0 If this key's channel does not support read operations then this method always returns false. return true if, and only if, readyOps() & OP_READ is nonzero throws CancelledKeyException If this key has been cancelled return (readyOps() & OP_READ) != 0;
public abstract boolean	isValid() Tells whether or not this key is valid. A key is valid upon creation and remains so until it is cancelled, its channel is closed, or its selector is closed. return true if, and only if, this key is valid
public final boolean	isWritable() Tests whether this key's channel is ready for writing. An invocation of this method of the form k.isWritable() behaves in exactly the same way as the expression k.readyOps() & OP_WRITE != 0 If this key's channel does not support write operations then this method always returns false. return true if, and only if, readyOps() & OP_WRITE is nonzero throws CancelledKeyException If this key has been cancelled return (readyOps() & OP_WRITE) != 0;
public abstract int	readyOps() Retrieves this key's ready-operation set. It is guaranteed that the returned set will only contain operation bits that are valid for this key's channel. return This key's ready-operation set throws CancelledKeyException If this key has been cancelled
public abstract java.nio.channels.Selector	selector() Returns the selector for which this key was created. This method will continue to return the selector even after the key is cancelled. return This key's selector