java.lang.Object
- java.nio.channels.Selector
- - java.nio.channels.spi.AbstractSelector

All Implemented Interfaces:

Closeable, AutoCloseable
```
public abstract class AbstractSelector
extends Selector
```
Base implementation class for selectors.
This class encapsulates the low-level machinery required to implement the interruption of selection operations. A concrete selector class must invoke the begin and end methods before and after, respectively, invoking an I/O operation that might block indefinitely. In order to ensure that the end method is always invoked, these methods should be used within a try ... finally block:
```
 try {
     begin();
     // Perform blocking I/O operation here
     ...
 } finally {
     end();
 }
```
This class also defines methods for maintaining a selector's cancelled-key set and for removing a key from its channel's key set, and declares the abstract register method that is invoked by a selectable channel's register method in order to perform the actual work of registering a channel.
Since:

1.4

Constructor Summary
Constructors
Modifier Constructor and Description

protected AbstractSelector(SelectorProvider provider)
Initializes a new instance of this class.

AbstractSelector (Java Platform SE 7 ) Home of API Java Contents Haut

Method Summary

Methods
Modifier and Type	Method and Description
`protected void`	`begin()` Marks the beginning of an I/O operation that might block indefinitely.
`protected Set<SelectionKey>`	`cancelledKeys()` Retrieves this selector's cancelled-key set.
`void`	`close()` Closes this selector.
`protected void`	`deregister(AbstractSelectionKey key)` Removes the given key from its channel's key set.
`protected void`	`end()` Marks the end of an I/O operation that might block indefinitely.
`protected abstract void`	`implCloseSelector()` Closes this selector.
`boolean`	`isOpen()` Tells whether or not this selector is open.
`SelectorProvider`	`provider()` Returns the provider that created this channel.
`protected abstract SelectionKey`	`register(AbstractSelectableChannel ch, int ops, Object att)` Registers the given channel with this selector.

AbstractSelector (Java Platform SE 7 ) Home of API Java Contents Haut

Methods inherited from class java.nio.channels.Selector keys, open, select, select, selectedKeys, selectNow, wakeup

Methods inherited from class java.lang.Object clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - AbstractSelector
    protected AbstractSelector(SelectorProvider provider)
    
    Initializes a new instance of this class.
- Method Detail
  - close
    public final void close() throws IOException
    
    Closes this selector.
    If the selector has already been closed then this method returns immediately. Otherwise it marks the selector as closed and then invokes the implCloseSelector method in order to complete the close operation.
    
    Specified by:
    
    close in interface Closeable
    
    Specified by:
    
    close in interface AutoCloseable
    
    Specified by:
    
    close in class Selector
    
    Throws:
    
    IOException - If an I/O error occurs
  - implCloseSelector
    protected abstract void implCloseSelector() throws IOException
    
    Closes this selector.
    This method is invoked by the close method in order to perform the actual work of closing the selector. This method is only invoked if the selector has not yet been closed, and it is never invoked more than once.
    An implementation of this method must arrange for any other thread that is blocked in a selection operation upon this selector to return immediately as if by invoking the wakeup method.
    
    Throws:
    
    IOException - If an I/O error occurs while closing the selector
  - isOpen
    public final boolean isOpen()
    
    Description copied from class: Selector
    
    Tells whether or not this selector is open.
    
    Specified by:
    
    isOpen in class Selector
    
    Returns:
    true if, and only if, this selector is open
  - provider
    public final SelectorProvider provider()
    
    Returns the provider that created this channel.
    
    Specified by:
    
    provider in class Selector
    
    Returns:
    The provider that created this channel
  - cancelledKeys
    protected final Set<SelectionKey> cancelledKeys()
    
    Retrieves this selector's cancelled-key set.
    This set should only be used while synchronized upon it.
    
    Returns:
    The cancelled-key set
  - register
    protected abstract SelectionKey register(AbstractSelectableChannel ch, int ops, Object att)
    
    Registers the given channel with this selector.
    This method is invoked by a channel's register method in order to perform the actual work of registering the channel with this selector.
    
    Parameters:
    ch - The channel to be registered
    ops - The initial interest set, which must be valid
    att - The initial attachment for the resulting key
    
    Returns:
    A new key representing the registration of the given channel with this selector
  - deregister
    protected final void deregister(AbstractSelectionKey key)
    
    Removes the given key from its channel's key set.
    This method must be invoked by the selector for each channel that it deregisters.
    
    Parameters:
    key - The selection key to be removed
  - begin
    protected final void begin()
    
    Marks the beginning of an I/O operation that might block indefinitely.
    This method should be invoked in tandem with the end method, using a try ... finally block as shown above, in order to implement interruption for this selector.
    Invoking this method arranges for the selector's wakeup method to be invoked if a thread's interrupt method is invoked while the thread is blocked in an I/O operation upon the selector.
  - end
    protected final void end()
    
    Marks the end of an I/O operation that might block indefinitely.
    This method should be invoked in tandem with the begin method, using a try ... finally block as shown above, in order to implement interruption for this selector.

Document created the 11/06/2005, last modified the 04/03/2020
Source of the printed document:https://www.gaudry.be/en/java-api-rf-java/nio/channels/spi/abstractselector.html

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References

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Contents Haut

Class AbstractSelector

References