AbstractMap | +--org.apache.commons.collections.ReferenceMap
java.lang.ref.Reference
static int | Constant indicating that hard references should be used. |
static int | Constant indicating that soft references should be used. |
static int | Constant indicating that weak references should be used. |
Constructs a new ReferenceMap that will use hard references to keys and soft references to values. |
ReferenceMap(int keyType, int valueType, boolean purgeValues) Constructs a new ReferenceMap that will use the specified types of references. |
ReferenceMap(int keyType, int valueType) Constructs a new ReferenceMap that will use the specified types of references. |
ReferenceMap(int keyType, int valueType, int capacity, float loadFactor, boolean purgeValues) Constructs a new ReferenceMap with the specified reference types, load factor and initial capacity. |
ReferenceMap(int keyType, int valueType, int capacity, float loadFactor) Constructs a new ReferenceMap with the specified reference types, load factor and initial capacity. |
void | clear() Clears this map. |
boolean | containsKey(Object key) Returns true if this map contains the given key. |
Set | entrySet() Returns a set view of this map's entries. |
Object | get(Object key) Returns the value associated with the given key, if any. |
boolean | isEmpty() Returns true if this map is empty. |
Set | keySet() Returns a set view of this map's keys. |
Object | put(Object key, Object value) Associates the given key with the given value. |
Object | remove(Object key) Removes the key and its associated value from this map. |
int | size() Returns the size of this map. |
Collection | values() Returns a collection view of this map's values. |
public static final int HARD
public static final int SOFT
public static final int WEAK
public ReferenceMap()
ReferenceMap
that will
use hard references to keys and soft references to values.
public ReferenceMap(int keyType, int valueType, boolean purgeValues)
ReferenceMap
that will
use the specified types of references.
public ReferenceMap(int keyType, int valueType, int capacity, float loadFactor, boolean purgeValues)
ReferenceMap
with the
specified reference types, load factor and initial
capacity.
public ReferenceMap(int keyType, int valueType, int capacity, float loadFactor)
ReferenceMap
with the
specified reference types, load factor and initial
capacity.
public ReferenceMap(int keyType, int valueType)
ReferenceMap
that will
use the specified types of references.
public void clear()
public boolean containsKey(Object key)
true
if this map contains the given key.
public Set entrySet()
public Object get(Object key)
public boolean isEmpty()
true
if this map is empty.
public Set keySet()
public Object put(Object key, Object value)
- if either the key or value
is nullpublic Object remove(Object key)
public int size()
public Collection values()
ReferenceMap
, you can specify what kind of references are used to store the map's keys and values. If non-hard references are used, then the garbage collector can remove mappings if a key or value becomes unreachable, or if the JVM's memory is running low. For information on how the different reference types behave, see Reference. Different types of references can be specified for keys and values. The keys can be configured to be weak but the values hard, in which case this class will behave like aWeakHashMap
. However, you can also specify hard keys and weak values, or any other combination. The default constructor uses hard keys and soft values, providing a memory-sensitive cache. The algorithms used are basically the same as those in java.util.HashMap. In particular, you can specify a load factor and capacity to suit your needs. All optional Map operations are supported. However, this Map implementation does not allow null elements. Attempting to add a null key or or a null value to the map will raise aNullPointerException
. As usual, this implementation is not synchronized. You can use java.util.Collections.synchronizedMap to provide synchronized access to aReferenceMap
.