# 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>

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");

The example above 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

- ## 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
  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

  Modifier and Type
  Method
  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`

  ### Methods inherited from interface java.util.Map

  `compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll`

- ## Constructor Details

  - ### 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 Details

  - ### 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

  - ### 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