visad.util
Class WeakMapValue

java.lang.Object
  java.lang.ref.Reference
      java.lang.ref.WeakReference
          visad.util.WeakMapValue

public final class WeakMapValue

extends WeakReference

A weakly-referenced Map value. The purpose of this class is to aid the creation of memory-sensitive, canonical mappings.

Nested Class Summary

Nested classes inherited from class java.lang.ref.Reference

Field Summary

Fields inherited from class java.lang.ref.Reference

Constructor Summary

WeakMapValue(Object key, Object value, ReferenceQueue queue)
Constructs from a key and value.

Method Summary

boolean	equals(Object obj) Indicates if this instance equals another object.
Object	getKey() Returns the key associated with this value.
Object	getValue() Returns the value associated with this value.
int	hashCode() Returns the hash code of this instance.

Methods inherited from class java.lang.ref.Reference

clear, enqueue, get, isEnqueued

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

WeakMapValue

public WeakMapValue(Object key,
                    Object value,
                    ReferenceQueue queue)

Constructs from a key and value. The key and value are not copied.

Parameters:

key - The key for the map.

value - The value for the map.

queue - The queue to receive garbaged-collected instances of this class.

Throws:

NullPointerException - if the queue is null.

Method Detail

getKey

public final Object getKey()

Returns the key associated with this value. The returned object is not a copy.

Returns:

The associated key.

getValue

public final Object getValue()

Returns the value associated with this value. The returned object is not a copy. It may be null if this reference object has been cleared by the program or garbage collector.

Returns:

The associated value or null.

equals

public boolean equals(Object obj)

Indicates if this instance equals another object. This method returns true if and only if the other object is a WeakMapValue and the values of both instances are either null or equal.

Parameters:

obj - The other object.

Returns:

True if and only if this instance equals the other object.

hashCode

public int hashCode()

Returns the hash code of this instance. This is the same as the hash code of the associated value.

Returns:

The hash code of this instance.