Package org.apache.commons.collections4.map

Class FixedSizeMap<K,V>

java.lang.Object
org.apache.commons.collections4.map.AbstractIterableMap<K,V>
org.apache.commons.collections4.map.AbstractMapDecorator<K,V>
org.apache.commons.collections4.map.FixedSizeMap<K,V>
Type Parameters:
K - the type of the keys in this map
V - the type of the values in this map
All Implemented Interfaces:
Serializable, Map<K,V>, BoundedMap<K,V>, Get<K,V>, IterableGet<K,V>, IterableMap<K,V>, Put<K,V>
public class FixedSizeMap<K,V> extends AbstractMapDecorator<K,V> implements BoundedMap<K,V>, Serializable
Decorates another Map to fix the size, preventing add/remove.

Any action that would change the size of the map is disallowed. The put method is allowed to change the value associated with an existing key however.

If trying to remove or clear the map, an UnsupportedOperationException is thrown. If trying to put a new mapping into the map, an IllegalArgumentException is thrown. This is because the put method can succeed if the mapping's key already exists in the map, so the put method is not always unsupported.

Note that FixedSizeMap is not synchronized and is not thread-safe. If you wish to use this map from multiple threads concurrently, you must use appropriate synchronization. The simplest approach is to wrap this map using Collections.synchronizedMap(Map). This class may throw exceptions when accessed by concurrent threads without synchronization.

This class is Serializable from Commons Collections 3.1.

Since:
3.0
See Also:

  • Constructor Details

    • FixedSizeMap

      protected FixedSizeMap(Map<K,V> map)
      Constructor that wraps (not copies).
      Parameters:
      map - the map to decorate, must not be null
      Throws:
      NullPointerException - if map is null

  • Method Details

    • fixedSizeMap

      public static <K, V> FixedSizeMap<K,V> fixedSizeMap(Map<K,V> map)
      Factory method to create a fixed size map.
      Type Parameters:
      K - the key type
      V - the value type
      Parameters:
      map - the map to decorate, must not be null
      Returns:
      a new fixed size map
      Throws:
      NullPointerException - if map is null
      Since:
      4.0

    • clear

      public void clear()
      Description copied from interface: Put
      Removes all of the mappings from this map.
      Specified by:
      clear in interface Map<K,V>
      Specified by:
      clear in interface Put<K,V>
      Overrides:
      clear in class AbstractMapDecorator<K,V>
      See Also:

    • entrySet

      public Set<Map.Entry<K,V>> entrySet()
      Description copied from interface: Get
      Gets a set view of the mappings contained in this map.
      Specified by:
      entrySet in interface Get<K,V>
      Specified by:
      entrySet in interface Map<K,V>
      Overrides:
      entrySet in class AbstractMapDecorator<K,V>
      Returns:
      a set view of the mappings contained in this map.
      See Also:

    • isFull

      public boolean isFull()
      Description copied from interface: BoundedMap
      Returns true if this map is full and no new elements can be added.
      Specified by:
      isFull in interface BoundedMap<K,V>
      Returns:
      true if the map is full

    • keySet

      public Set<K> keySet()
      Description copied from interface: Get
      Gets a view of the keys contained in this map.
      Specified by:
      keySet in interface Get<K,V>
      Specified by:
      keySet in interface Map<K,V>
      Overrides:
      keySet in class AbstractMapDecorator<K,V>
      Returns:
      a set view of the keys contained in this map
      See Also:

    • maxSize

      public int maxSize()
      Description copied from interface: BoundedMap
      Gets the maximum size of the map (the bound).
      Specified by:
      maxSize in interface BoundedMap<K,V>
      Returns:
      the maximum number of elements the map can hold

    • put

      public V put(K key, V value)
      Description copied from interface: Put
      Associates the specified value with the specified key in this map.

      Note that the return type is Object, rather than V as in the Map interface. See the class Javadoc for further info.

      Specified by:
      put in interface Map<K,V>
      Specified by:
      put in interface Put<K,V>
      Overrides:
      put in class AbstractMapDecorator<K,V>
      Parameters:
      key - key with which the specified value is to be associated
      value - value to be associated with the specified key
      Returns:
      the previous value associated with key, or null if there was no mapping for key. (A null return can also indicate that the map previously associated null with key, if the implementation supports null values.)
      See Also:

    • putAll

      public void putAll(Map<? extends K,? extends V> mapToCopy)
      Description copied from interface: Put
      Copies all of the mappings from the specified map to this map.
      Specified by:
      putAll in interface Map<K,V>
      Specified by:
      putAll in interface Put<K,V>
      Overrides:
      putAll in class AbstractMapDecorator<K,V>
      Parameters:
      mapToCopy - mappings to be stored in this map
      See Also:

    • remove

      public V remove(Object key)
      Description copied from interface: Get
      Remove a key-value mappings.
      Specified by:
      remove in interface Get<K,V>
      Specified by:
      remove in interface Map<K,V>
      Overrides:
      remove in class AbstractMapDecorator<K,V>
      Parameters:
      key - key whose mapping is to be removed from the map
      Returns:
      the previous value associated with key, or null if there was no mapping for key.
      See Also:

    • values

      public Collection<V> values()
      Description copied from interface: Get
      Gets a a collection view of the values contained in this map.
      Specified by:
      values in interface Get<K,V>
      Specified by:
      values in interface Map<K,V>
      Overrides:
      values in class AbstractMapDecorator<K,V>
      Returns:
      a collection view of the values contained in this map.
      See Also: