What is The SelectionKey Class in Java
The SelectionKey class in Java is a part of the Java NIO (New I/O) package. It represents the registration of a channel with a Selector object and contains information about the registered channel, such as its readiness to perform I/O operations, and the operations that the channel is interested in, such as reading or writing data.
SelectionKey objects are returned by the Selector when a channel is registered. They contain information about the registered channel and the events that the channel is interested in, such as reading or writing data. SelectionKey objects can be used to modify the interest set of the channel or to retrieve the set of operations that are ready for I/O on the channel.
The SelectionKey class provides several methods to access the information stored in the selection key, including channel(), selector(), interestOps(), readyOps(), and attach(Object obj). The channel() method returns the channel that this selection key is associated with, while the selector() method returns the Selector object that this selection key is registered with. The interestOps() method returns the interest set of operations for this selection key, while the readyOps() method returns the set of operations that are ready for I/O on this selection key. The attach(Object obj) method attaches an arbitrary object to this selection key for use by the application.
The SelectionKey class is used in Java programming to manage multiple network connections efficiently by allowing a single thread to manage multiple channels. This approach reduces latency, as I/O operations can be performed asynchronously, and it allows for better resource utilization and improved performance. The SelectionKey class also provides support for application-specific data by allowing arbitrary objects to be attached to selection keys.