Package org.apache.commons.collections4.map

Class 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:
    java.io.Serializable, java.util.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, java.io.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

        java.util.Map.Entry<K extends java.lang.Object,​V extends java.lang.Object>

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()  
      java.util.Set<java.util.Map.Entry<K,​V>> entrySet()  
      java.util.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​(java.util.Map<? extends K,​? extends V> mapToCopy)  
      V remove​(java.lang.Object key)  
      static <K,​V>
      java.util.Map<K,​V>      		 unmodifiableMap​(java.util.Map<? extends K,​? extends V> map)
      Factory method to create an unmodifiable map.
      java.util.Collection<V> values()  

      • Methods inherited from class java.lang.Object

        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> java.util.Map<K,​V> unmodifiableMap​(java.util.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:
        java.lang.NullPointerException - if map is null
        Since:
        4.0

      • clear

        public void clear()
        Specified by:
        clear in interface java.util.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 java.util.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​(java.util.Map<? extends K,​? extends V> mapToCopy)
        Specified by:
        putAll in interface java.util.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​(java.lang.Object key)
        Specified by:
        remove in interface Get<K,​V>
        Specified by:
        remove in interface java.util.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:
        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 java.util.Set<java.util.Map.Entry<K,​V>> entrySet()
        Specified by:
        entrySet in interface Get<K,​V>
        Specified by:
        entrySet in interface java.util.Map<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 java.util.Set<K> keySet()
        Specified by:
        keySet in interface Get<K,​V>
        Specified by:
        keySet in interface java.util.Map<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 java.util.Collection<V> values()
        Specified by:
        values in interface Get<K,​V>
        Specified by:
        values in interface java.util.Map<K,​V>
        Overrides:
        values in class AbstractMapDecorator<K,​V>
        Returns:
        a collection view of the values contained in this map
        See Also:
        Map.values()