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:

  • Field Details

    • serialVersionUID

      private static final long serialVersionUID
      Serialization version
      See Also:

  • Constructor Details

    • UnmodifiableMap

      private UnmodifiableMap(Map<? extends K, ? extends 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

    • 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

    • writeObject

      private void writeObject(ObjectOutputStream out) throws IOException
      Write the map out using a custom routine.
      Parameters:
      out - the output stream
      Throws:
      IOException - if an error occurs while writing to the stream
      Since:
      3.1

    • readObject

      private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException
      Read the map in using a custom routine.
      Parameters:
      in - the input stream
      Throws:
      IOException - if an error occurs while reading from the stream
      ClassNotFoundException - if an object read from the stream can not be loaded
      Since:
      3.1

    • 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:

    • 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:

    • 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:

    • remove

      public V remove(Object key)
      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:

    • 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 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:

    • keySet

      public Set<K> keySet()
      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:

    • values

      public Collection<V> values()
      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: