Package org.geotools.util

Class 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:
    WeakHashMap, WeakHashSet

    • Nested Class Summary

      • Nested classes/interfaces inherited from class AbstractMap

        AbstractMap.SimpleEntry<K extends Object,​V extends Object>, AbstractMap.SimpleImmutableEntry<K extends Object,​V extends Object>

    • Constructor Summary

      Constructors 
      Constructor Description
      WeakValueHashMap()
      Creates a WeakValueHashMap.
      WeakValueHashMap​(int initialSize)
      Creates a WeakValueHashMap of the requested size and default load factor.
      WeakValueHashMap​(Map<K,​V> map)
      Creates a new WeakValueHashMap populated with the contents of the provied map.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()
      Removes all of the elements from this map.
      boolean containsKey​(Object key)
      Returns true if this map contains a mapping for the specified key.
      boolean containsValue​(Object value)
      Returns true if this map maps one or more keys to this value.
      Set<Map.Entry<K,​V>> entrySet()
      Returns a set view of the mappings contained in this map.
      V get​(Object key)
      Returns the value to which this map maps the specified key.
      V put​(K key, V value)
      Associates the specified value with the specified key in this map.
      V remove​(Object key)
      Removes the mapping for this key from this map if present.
      int size()
      Returns the number of key-value mappings in this map.

      • Methods inherited from class AbstractMap

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

      • Methods inherited from class Object

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

      • Methods inherited from interface Map

        compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll

    • Constructor Detail

      • 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 Detail

      • 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.