Package org.geotools.util

Class WeakValueHashMap<K,V>

Object
AbstractMap<K,V>
WeakValueHashMap<K,V>
Type Parameters:
K - The class of key elements.
V - The class of value elements.
All Implemented Interfaces:
Map<K,V>
public class WeakValueHashMap<K,V> extends AbstractMap<K,V>
A hashtable-based Map implementation with weak values. An entry in a WeakValueHashMap will automatically be removed when its value is no longer in ordinary use. This class is similar to the standard WeakHashMap class provided in J2SE, except that weak references are hold on values instead of keys.

The WeakValueHashMap class is thread-safe.

Since:
2.0
Author:
Martin Desruisseaux (IRD)
See Also:

  • Constructor Details

    • WeakValueHashMap

      public WeakValueHashMap()
      Creates a WeakValueHashMap.

    • WeakValueHashMap

      public WeakValueHashMap(int initialSize)
      Creates a WeakValueHashMap of the requested size and default load factor.
      Parameters:
      initialSize - The initial size.

    • WeakValueHashMap

      public WeakValueHashMap(Map<K,V> map)
      Creates a new WeakValueHashMap populated with the contents of the provied map.
      Parameters:
      map - Initial contents of the WeakValueHashMap.

  • Method Details

    • size

      public int size()
      Returns the number of key-value mappings in this map.
      Specified by:
      size in interface Map<K,V>
      Overrides:
      size in class AbstractMap<K,V>

    • containsValue

      public boolean containsValue(Object value)
      Returns true if this map maps one or more keys to this value.
      Specified by:
      containsValue in interface Map<K,V>
      Overrides:
      containsValue in class AbstractMap<K,V>
      Parameters:
      value - value whose presence in this map is to be tested.
      Returns:
      true if this map maps one or more keys to this value.

    • containsKey

      public boolean containsKey(Object key)
      Returns true if this map contains a mapping for the specified key.
      Specified by:
      containsKey in interface Map<K,V>
      Overrides:
      containsKey in class AbstractMap<K,V>
      Parameters:
      key - key whose presence in this map is to be tested.
      Returns:
      true if this map contains a mapping for the specified key.
      Throws:
      NullPointerException - If key is null.

    • get

      public V get(Object key)
      Returns the value to which this map maps the specified key. Returns null if the map contains no mapping for this key.
      Specified by:
      get in interface Map<K,V>
      Overrides:
      get in class AbstractMap<K,V>
      Parameters:
      key - Key whose associated value is to be returned.
      Returns:
      The value to which this map maps the specified key.
      Throws:
      NullPointerException - if the key is null.

    • put

      public V put(K key, V value)
      Associates the specified value with the specified key in this map. The value is associated using a WeakReference.
      Specified by:
      put in interface Map<K,V>
      Overrides:
      put in class AbstractMap<K,V>
      Parameters:
      key - key with which the specified value is to be associated.
      value - value to be associated with the specified key.
      Returns:
      previous value associated with specified key, or null if there was no mapping for key.
      Throws:
      NullPointerException - if the key or the value is null.

    • remove

      public V remove(Object key)
      Removes the mapping for this key from this map if present.
      Specified by:
      remove in interface Map<K,V>
      Overrides:
      remove in class AbstractMap<K,V>
      Parameters:
      key - key whose mapping is to be removed from the map.
      Returns:
      previous value associated with specified key, or null if there was no entry for key.

    • clear

      public void clear()
      Removes all of the elements from this map.
      Specified by:
      clear in interface Map<K,V>
      Overrides:
      clear in class AbstractMap<K,V>

    • entrySet

      public Set<Map.Entry<K,V>> entrySet()
      Returns a set view of the mappings contained in this map. Each element in this set is a Map.Entry. The current implementation thrown UnsupportedOperationException.
      Specified by:
      entrySet in interface Map<K,V>
      Specified by:
      entrySet in class AbstractMap<K,V>
      Returns:
      a set view of the mappings contained in this map.