org.apache.commons.collections4.map

## Class AbstractMapDecorator<K,V>

- java.lang.Object
- - org.apache.commons.collections4.map.AbstractIterableMap<K,V>
  - - org.apache.commons.collections4.map.AbstractMapDecorator<K,V>

- Type Parameters:
    `K` - the type of the keys in the map
    `V` - the type of the values in the map
  All Implemented Interfaces:
    Map<K,V>, Get<K,V>, IterableGet<K,V>, IterableMap<K,V>, Put<K,V>
  Direct Known Subclasses:
    AbstractBidiMapDecorator, AbstractOrderedMapDecorator, AbstractSortedMapDecorator, DefaultedMap, FixedSizeMap, LazyMap, ListOrderedMap, MultiKeyMap, MultiValueMap, PassiveExpiringMap, PredicatedMap, TransformedMap, UnmodifiableMap

      public abstract class AbstractMapDecorator<K,V>
      extends AbstractIterableMap<K,V>

  Provides a base decorator that enables additional functionality to be added to a Map via decoration.

  Methods are forwarded directly to the decorated map.

  This implementation does not perform any special processing with `entrySet()`, `keySet()` or `values()`. Instead it simply returns the set/collection from the wrapped map. This may be undesirable, for example if you are trying to write a validating implementation it would provide a loophole around the validation. But, you might want that loophole, so this class is kept simple.

  Since:
    3.0

- - ### Nested Class Summary

    - ### Nested classes/interfaces inherited from interface java.util.Map

      `Map.Entry<K,V>`

  - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `AbstractMapDecorator()` Constructor only used in deserialization, do not use otherwise.
    `protected` | `AbstractMapDecorator(Map<K,V> map)` Constructor that wraps (not copies).

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `clear()`
    `boolean` | `containsKey(Object key)`
    `boolean` | `containsValue(Object value)`
    `protected Map<K,V>` | `decorated()` Gets the map being decorated.
    `Set<Map.Entry<K,V>>` | `entrySet()`
    `boolean` | `equals(Object object)`
    `V` | `get(Object key)`
    `int` | `hashCode()`
    `boolean` | `isEmpty()`
    `Set<K>` | `keySet()`
    `V` | `put(K key, V value)` Note that the return type is Object, rather than V as in the Map interface.
    `void` | `putAll(Map<? extends K,? extends V> mapToCopy)`
    `V` | `remove(Object key)`
    `int` | `size()`
    `String` | `toString()`
    `Collection<V>` | `values()`

    - ### Methods inherited from class org.apache.commons.collections4.map.AbstractIterableMap

      `mapIterator`

    - ### Methods inherited from class java.lang.Object

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

    - ### Methods inherited from interface java.util.Map

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

- - ### Constructor Detail

    - #### AbstractMapDecorator

          protected AbstractMapDecorator()

      Constructor only used in deserialization, do not use otherwise.
      Since:
        3.1

    - #### AbstractMapDecorator

          protected AbstractMapDecorator(Map<K,V> map)

      Constructor that wraps (not copies).
      Parameters:
        `map` - the map to decorate, must not be null
      Throws:
        `NullPointerException` - if the map is null

  - ### Method Detail

    - #### decorated

          protected Map<K,V> decorated()

      Gets the map being decorated.
      Returns:
        the decorated map

    - #### clear

          public void clear()

      See Also:
        `Map.clear()`

    - #### containsKey

          public boolean containsKey(Object key)

      Parameters:
        `key` - key whose presence in this map is to be tested
      Returns:
        `true` if this map contains a mapping for the specified key
      See Also:
        `Map.containsKey(Object)`

    - #### containsValue

          public boolean containsValue(Object value)

      Parameters:
        `value` - value whose presence in this map is to be tested
      Returns:
        `true` if this map maps one or more keys to the specified value
      See Also:
        `Map.containsValue(Object)`

    - #### entrySet

          public Set<Map.Entry<K,V>> entrySet()

      Returns:
        a set view of the mappings contained in this map
      See Also:
        `Map.entrySet()`

    - #### get

          public V get(Object key)

      Parameters:
        `key` - the key whose associated value is to be returned
      Returns:
        the value to which the specified key is mapped, or `null` if this map contains no mapping for the key
      See Also:
        `Map.get(Object)`

    - #### isEmpty

          public boolean isEmpty()

      Returns:
        `true` if this map contains no key-value mappings
      See Also:
        `Map.isEmpty()`

    - #### keySet

          public Set<K> keySet()

      Returns:
        a set view of the keys contained in this map
      See Also:
        `Map.keySet()`

    - #### put

          public V put(K key,
                       V value)

      Description copied from interface: `Put`
      Note that the return type is Object, rather than V as in the Map interface. See the class Javadoc for further info.
      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:
        `Map.put(Object, Object)`

    - #### putAll

          public void putAll(Map<? extends K,? extends V> mapToCopy)

      Parameters:
        `mapToCopy` - mappings to be stored in this map
      See Also:
        `Map.putAll(Map)`

    - #### remove

          public V remove(Object key)

      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:
        `Map.remove(Object)`

    - #### size

          public int size()

      Returns:
        the number of key-value mappings in this map
      See Also:
        `Map.size()`

    - #### values

          public Collection<V> values()

      Returns:
        a collection view of the values contained in this map
      See Also:
        `Map.values()`

    - #### equals

          public boolean equals(Object object)

      Specified by:
        `equals` in interface `Map<K,V>`
      Overrides:
        `equals` in class `Object`

    - #### hashCode

          public int hashCode()

      Specified by:
        `hashCode` in interface `Map<K,V>`
      Overrides:
        `hashCode` in class `Object`

    - #### toString

          public String toString()

      Overrides:
        `toString` in class `Object`

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