org.apache.commons.collections4.map

## Class UnmodifiableMap<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.UnmodifiableMap<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>, Get<K,V>, IterableGet<K,V>, IterableMap<K,V>, Put<K,V>, Unmodifiable

      public final class UnmodifiableMap<K,V>
      extends AbstractMapDecorator<K,V>
      implements Unmodifiable, Serializable

  Decorates another `Map` to ensure it can't be altered.

  This class is Serializable from Commons Collections 3.1.

  Attempts to modify it will result in an UnsupportedOperationException.

  Since:
    3.0
  See Also:
    Serialized Form

- - ### Nested Class Summary

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

      `Map.Entry<K,V>`

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `clear()`
    `Set<Map.Entry<K,V>>` | `entrySet()`
    `Set<K>` | `keySet()`
    `MapIterator<K,V>` | `mapIterator()` Obtains a `MapIterator` over the map.
    `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)`
    `static <K,V> Map<K,V>` | `unmodifiableMap(Map<? extends K,? extends V> map)` Factory method to create an unmodifiable map.
    `Collection<V>` | `values()`

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

      `containsKey, containsValue, decorated, equals, get, hashCode, isEmpty, size, toString`

    - ### 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`

- - ### Method Detail

    - #### unmodifiableMap

          public static <K,V> Map<K,V> unmodifiableMap(Map<? extends K,? extends V> map)

      Factory method to create an unmodifiable map.
      Type Parameters:
        `K` - the key type
        `V` - the value type
      Parameters:
        `map` - the map to decorate, must not be null
      Returns:
        a new unmodifiable map
      Throws:
        `NullPointerException` - if map is null
      Since:
        4.0

    - #### clear

          public void clear()

      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:
        `Map.clear()`

    - #### 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.
      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:
        `Map.put(Object, Object)`

    - #### putAll

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

      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:
        `Map.putAll(Map)`

    - #### remove

          public V remove(Object key)

      Specified by:
        `remove` in interface `Map<K,V>`
      Specified by:
        `remove` in interface `Get<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:
        `Map.remove(Object)`

    - #### mapIterator

          public MapIterator<K,V> mapIterator()

      Description copied from class: `AbstractIterableMap`
      Obtains a `MapIterator` over the map.

      A map iterator is an efficient way of iterating over maps. There is no need to access the entry set or use Map Entry objects.

           IterableMap<String,Integer> map = new HashedMap<String,Integer>();
           MapIterator<String,Integer> it = map.mapIterator();
           while (it.hasNext()) {
             String key = it.next();
             Integer value = it.getValue();
             it.setValue(value + 1);
           }

      Specified by:
        `mapIterator` in interface `IterableGet<K,V>`
      Overrides:
        `mapIterator` in class `AbstractIterableMap<K,V>`
      Returns:
        a map iterator

    - #### entrySet

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

      Specified by:
        `entrySet` in interface `Map<K,V>`
      Specified by:
        `entrySet` in interface `Get<K,V>`
      Overrides:
        `entrySet` in class `AbstractMapDecorator<K,V>`
      Returns:
        a set view of the mappings contained in this map
      See Also:
        `Map.entrySet()`

    - #### keySet

          public Set<K> keySet()

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

    - #### values

          public Collection<V> values()

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

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