org.apache.commons.collections4.map

## Class CaseInsensitiveMap<K,V>

- java.lang.Object
- - java.util.AbstractMap<K,V>
  - - org.apache.commons.collections4.map.AbstractHashedMap<K,V>
    - - org.apache.commons.collections4.map.CaseInsensitiveMap<K,V>

- 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
  Version:
    $Id: CaseInsensitiveMap.java 1533984 2013-10-20 21:12:51Z tn $
  See Also:
    Serialized Form

- - ### Nested Class Summary

    - ### Nested classes/interfaces inherited from class org.apache.commons.collections4.map.AbstractHashedMap

      `AbstractHashedMap.EntrySet<K,V>, AbstractHashedMap.EntrySetIterator<K,V>, AbstractHashedMap.HashEntry<K,V>, AbstractHashedMap.HashIterator<K,V>, AbstractHashedMap.HashMapIterator<K,V>, AbstractHashedMap.KeySet<K>, AbstractHashedMap.KeySetIterator<K>, AbstractHashedMap.Values<V>, AbstractHashedMap.ValuesIterator<V>`

    - ### Nested classes/interfaces inherited from class java.util.AbstractMap

      `AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>`

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

      `Map.Entry<K,V>`

  - ### Field Summary

    - ### Fields inherited from class org.apache.commons.collections4.map.AbstractHashedMap

      `DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_THRESHOLD, GETKEY_INVALID, GETVALUE_INVALID, MAXIMUM_CAPACITY, NO_NEXT_ENTRY, NO_PREVIOUS_ENTRY, NULL, REMOVE_INVALID, SETVALUE_INVALID`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `CaseInsensitiveMap()` Constructs a new empty map with default size and load factor.
    `CaseInsensitiveMap(int initialCapacity)` Constructs a new, empty map with the specified initial capacity.
    `CaseInsensitiveMap(int initialCapacity, float loadFactor)` Constructs a new, empty map with the specified initial capacity and load factor.
    `CaseInsensitiveMap(Map<? extends K,? extends V> map)` Constructor copying elements from another map.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `CaseInsensitiveMap<K,V>` | `clone()` Clones the map without cloning the keys or values.
    `protected Object` | `convertKey(Object key)` Overrides convertKey() from `AbstractHashedMap` to convert keys to lower case.

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

      `addEntry, addMapping, calculateNewCapacity, calculateThreshold, checkCapacity, clear, containsKey, containsValue, createEntry, createEntrySetIterator, createKeySetIterator, createValuesIterator, destroyEntry, doReadObject, doWriteObject, ensureCapacity, entryHashCode, entryKey, entryNext, entrySet, entryValue, equals, get, getEntry, hash, hashCode, hashIndex, init, isEmpty, isEqualKey, isEqualValue, keySet, mapIterator, put, putAll, remove, removeEntry, removeMapping, reuseEntry, size, toString, updateEntry, values`

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

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

- - ### 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

  - ### Method Detail

    - #### convertKey

          protected Object convertKey(Object key)

      Overrides convertKey() from `AbstractHashedMap` to convert keys to lower case.

      Returns `AbstractHashedMap.NULL` if key is null.

      Overrides:
        `convertKey` in class `AbstractHashedMap<K,V>`
      Parameters:
        `key` - the key convert
      Returns:
        the converted key

    - #### clone

          public CaseInsensitiveMap<K,V> clone()

      Clones the map without cloning the keys or values.
      Overrides:
        `clone` in class `AbstractHashedMap<K,V>`
      Returns:
        a shallow clone

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