```
public interface Selector
```
A multiplexor of instances of Selectable.
Many instances of Selectable can be added to a selector, and the select(long) method used to block the calling thread until one of the Selectables becomes read to perform an operation.
This class is not thread safe, so only one thread should be manipulating the contents of the selector, or running the select(long) method at any given time.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`add(Selectable selectable)`	Adds a selectable to the selector.
`java.util.Iterator<Selectable>`	`error()`
`java.util.Iterator<Selectable>`	`expired()`
`void`	`free()`	Frees the resources used by this selector.
`java.util.Iterator<Selectable>`	`readable()`
`void`	`remove(Selectable selectable)`	Removes a selectable from the selector.
`void`	`select(long timeout)`	Waits for the specified timeout period for one or more selectables to become ready for an operation.
`void`	`update(Selectable selectable)`	Updates the selector to reflect any changes interest by the specified selectable.
`java.util.Iterator<Selectable>`	`writeable()`

- Method Detail
  - add
```
void add(Selectable selectable)
  throws java.io.IOException
```
    Adds a selectable to the selector.
    
    Parameters:
    
    selectable -
    
    Throws:
    
    java.io.IOException
  - update
```
void update(Selectable selectable)
```
    Updates the selector to reflect any changes interest by the specified selectable. This is achieved by calling the Selectable.isReading() and Selectable.isWriting() methods.
    
    Parameters:
    
    selectable -
  - remove
```
void remove(Selectable selectable)
```
    Removes a selectable from the selector.
    
    Parameters:
    
    selectable -
  - select
```
void select(long timeout)
     throws java.io.IOException
```
    Waits for the specified timeout period for one or more selectables to become ready for an operation. Selectables that become ready are returned by the readable(), writeable(), expired(), or error() methods.
    
    Parameters:
    
    timeout - the maximum number of milliseconds to block the calling thread waiting for a selectable to become ready for an operation. The value zero is interpreted as check but don't block.
    
    Throws:
    
    java.io.IOException
  - readable
```
java.util.Iterator<Selectable> readable()
```
    Returns:
    
    the selectables that have become readable since the last call to select(long). Calling select clears any previous values in this set before adding new values corresponding to those selectables that have become readable.
  - writeable
```
java.util.Iterator<Selectable> writeable()
```
    Returns:
    
    the selectables that have become writable since the last call to select(long). Calling select clears any previous values in this set before adding new values corresponding to those selectables that have become writable.
  - expired
```
java.util.Iterator<Selectable> expired()
```
    Returns:
    
    the selectables that have expired since the last call to select(long). Calling select clears any previous values in this set before adding new values corresponding to those selectables that have now expired.
  - error
```
java.util.Iterator<Selectable> error()
```
    Returns:
    
    the selectables that have encountered an error since the last call to select(long). Calling select clears any previous values in this set before adding new values corresponding to those selectables that have encountered an error.
  - free
```
void free()
```
    Frees the resources used by this selector.

Interface Selector

Method Summary

Method Detail

add

update

remove

select

readable

writeable

expired

error

free