Package org.apache.commons.collections4.map

Class CaseInsensitiveMap<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, Cloneable, Map<K,​V>, Get<K,​V>, IterableGet<K,​V>, IterableMap<K,​V>, Put<K,​V>
    public class CaseInsensitiveMap<K,​V>
extends AbstractHashedMap<K,​V>
implements Serializable, Cloneable
    A case-insensitive Map.

    Before keys are added to the map or compared to other existing keys, they are converted to all lowercase in a locale-independent fashion by using information from the Unicode data file.

    Null keys are supported.

    The keySet() method returns all lowercase keys, or nulls.

    Example: 

    
  Map<String, String> map = new CaseInsensitiveMap<String, String>();
  map.put("One", "One");
  map.put("Two", "Two");
  map.put(null, "Three");
  map.put("one", "Four");
    creates a CaseInsensitiveMap with three entries.
    map.get(null) returns "Three" and map.get("ONE") returns "Four". The Set returned by keySet() equals {"one", "two", null}.

    This map will violate the detail of various Map and map view contracts. As a general rule, don't compare this map to other maps. In particular, you can't use decorators like ListOrderedMap on it, which silently assume that these contracts are fulfilled.

    Note that CaseInsensitiveMap 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.

    Since:
    3.0
    See Also:
    Serialized Form

    • Constructor Detail

      • CaseInsensitiveMap

        public CaseInsensitiveMap()
        Constructs a new empty map with default size and load factor.

      • CaseInsensitiveMap

        public CaseInsensitiveMap​(int initialCapacity)
        Constructs a new, empty map with the specified initial capacity.
        Parameters:
        initialCapacity - the initial capacity
        Throws:
        IllegalArgumentException - if the initial capacity is negative

      • CaseInsensitiveMap

        public CaseInsensitiveMap​(int initialCapacity,
                          float loadFactor)
        Constructs a new, empty map with the specified initial capacity and load factor.
        Parameters:
        initialCapacity - the initial capacity
        loadFactor - the load factor
        Throws:
        IllegalArgumentException - if the initial capacity is negative
        IllegalArgumentException - if the load factor is less than zero

      • CaseInsensitiveMap

        public CaseInsensitiveMap​(Map<? extends K,​? extends V> map)
        Constructor copying elements from another map.

        Keys will be converted to lower case strings, which may cause some entries to be removed (if string representation of keys differ only by character case).

        Parameters:
        map - the map to copy
        Throws:
        NullPointerException - if the map is null