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WeakValueHashMap (JBoss/Common API) - JBoss 4.0.1 sp1 common API Documentation 英文版文档

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org.jboss.util.collection
Class WeakValueHashMap

java.lang.Object
  java.util.AbstractMap
      org.jboss.util.collection.WeakValueHashMap

All Implemented Interfaces:

Map

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public class WeakValueHashMap

extends AbstractMap

implements Map

This Map will remove entries when the value in the map has been cleaned from garbage collection

Version:

$Revision: 1.4 $

Author:

Bill Burke

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Nested Class Summary

 

Nested classes inherited from class java.util.Map

Map.Entry

 

Constructor Summary

WeakValueHashMap()           Constructs a new, empty WeakHashMap with the default initial capacity and the default load factor, which is 0.75.

WeakValueHashMap(int initialCapacity)           Constructs a new, empty WeakHashMap with the given initial capacity and the default load factor, which is 0.75.

WeakValueHashMap(int initialCapacity, float loadFactor)           Constructs a new, empty WeakHashMap with the given initial capacity and the given load factor.

WeakValueHashMap(Map t)           Constructs a new WeakHashMap with the same mappings as the specified Map.

 

Method Summary
void	clear()           Removes all mappings from this map.
boolean	containsKey(Object key)           Returns true if this map contains a mapping for the specified key.
Set	entrySet()
Object	get(Object key)           Returns the value to which this map maps the specified key.
boolean	isEmpty()           Returns true if this map contains no key-value mappings.
Object	put(Object key, Object value)           Updates this map so that the given key maps to the given value.
Object	remove(Object key)           Removes the mapping for the given key from this map, if present.
int	size()           Returns the number of key-value mappings in this map.

 

Methods inherited from class java.util.AbstractMap

clone, containsValue, equals, hashCode, keySet, putAll, toString, values

 

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

 

Methods inherited from interface java.util.Map

containsValue, equals, hashCode, keySet, putAll, values

 

Constructor Detail

WeakValueHashMap

public WeakValueHashMap(int initialCapacity,
                        float loadFactor)

Constructs a new, empty WeakHashMap with the given initial capacity and the given load factor.

Parameters:

initialCapacity - The initial capacity of the WeakHashMap

loadFactor - The load factor of the WeakHashMap

Throws:

IllegalArgumentException - If the initial capacity is less than zero, or if the load factor is nonpositive

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WeakValueHashMap

public WeakValueHashMap(int initialCapacity)

Constructs a new, empty WeakHashMap with the given initial capacity and the default load factor, which is 0.75.

Parameters:

initialCapacity - The initial capacity of the WeakHashMap

Throws:

IllegalArgumentException - If the initial capacity is less than zero

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WeakValueHashMap

public WeakValueHashMap()

Constructs a new, empty WeakHashMap with the default initial capacity and the default load factor, which is 0.75.

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WeakValueHashMap

public WeakValueHashMap(Map t)

Constructs a new WeakHashMap with the same mappings as the specified Map. The WeakHashMap is created with an initial capacity of twice the number of mappings in the specified map or 11 (whichever is greater), and a default load factor, which is 0.75.

Parameters:

t - the map whose mappings are to be placed in this map.

Since:

1.3

Method Detail

entrySet

public Set entrySet()

Specified by:

entrySet in interface Map

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size

public int size()

Returns the number of key-value mappings in this map. Note: In contrast with most implementations of the Map interface, the time required by this operation is linear in the size of the map.

Specified by:

size in interface Map

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isEmpty

public boolean isEmpty()

Returns true if this map contains no key-value mappings.

Specified by:

isEmpty in interface Map

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containsKey

public boolean containsKey(Object key)

Returns true if this map contains a mapping for the specified key.

Specified by:

containsKey in interface Map

Parameters:

key - The key whose presence in this map is to be tested

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get

public Object get(Object key)

Returns the value to which this map maps the specified key. If this map does not contain a value for this key, then return null.

Specified by:

get in interface Map

Parameters:

key - The key whose associated value, if any, is to be returned

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put

public Object put(Object key,
                  Object value)

Updates this map so that the given key maps to the given value. If the map previously contained a mapping for key then that mapping is replaced and the previous value is returned.

Specified by:

put in interface Map

Parameters:

key - The key that is to be mapped to the given value

value - The value to which the given key is to be mapped

Returns:

The previous value to which this key was mapped, or null if if there was no mapping for the key

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remove

public Object remove(Object key)

Removes the mapping for the given key from this map, if present.

Specified by:

remove in interface Map

Parameters:

key - The key whose mapping is to be removed

Returns:

The value to which this key was mapped, or null if there was no mapping for the key

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clear

public void clear()

Removes all mappings from this map.

Specified by:

clear in interface Map

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