org.eclipse.core.internal.registry

Class ReferenceMap

java.lang.Object

org.eclipse.core.internal.registry.ReferenceMap

public class ReferenceMap
extends java.lang.Object

Hashtable-based map with integer keys that allows values to be removed by the garbage collector.

When you construct a ReferenceMap, you can specify what kind of references are used to store the map's values. If non-hard references are used, then the garbage collector can remove mappings if a value becomes unreachable, or if the JVM's memory is running low. For information on how the different reference types behave, see Reference.

The algorithms used are basically the same as those in HashMap. In particular, you can specify a load factor and capacity to suit your needs. This map does not allow null values. Attempting to add a null value to the map will raise a NullPointerException.

This data structure is not synchronized.

See Also:

Reference

Field Summary

Fields

Modifier and Type	Field and Description
static int	HARD Constant indicating that hard references should be used.
static int	SOFT Constant indiciating that soft references should be used.

Constructor Summary

Constructors

Constructor and Description
ReferenceMap(int referenceType, int capacity, float loadFactor) Constructs a new ReferenceMap with the specified reference type, load factor and initial capacity.

Method Summary

Modifier and Type	Method and Description
java.lang.Object	get(int key) Returns the value associated with the given key, if any.
void	put(int key, java.lang.Object value) Associates the given key with the given value.
java.lang.Object	remove(int key) Removes the key and its associated value from this map.

Methods inherited from class java.lang.Object

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

Field Detail

HARD

public static final int HARD

Constant indicating that hard references should be used.

See Also:

Constant Field Values

SOFT

public static final int SOFT

Constant indiciating that soft references should be used.

See Also:

Constant Field Values

Constructor Detail

ReferenceMap

public ReferenceMap(int referenceType,
                    int capacity,
                    float loadFactor)

Constructs a new ReferenceMap with the specified reference type, load factor and initial capacity.

Parameters:

referenceType - the type of reference to use for values; must be HARD or SOFT

capacity - the initial capacity for the map

loadFactor - the load factor for the map

Method Detail

get

public java.lang.Object get(int key)

Returns the value associated with the given key, if any.

Returns:

the value associated with the given key, or null if the key maps to no value

put

public void put(int key,
                java.lang.Object value)

Associates the given key with the given value.

Neither the key nor the value may be null.

Parameters:

key - the key of the mapping

value - the value of the mapping

Throws:

java.lang.NullPointerException - if either the key or value is null

remove

public java.lang.Object remove(int key)

Removes the key and its associated value from this map.

Parameters:

key - the key to remove

Returns:

the value associated with that key, or null if the key was not in the map