org.apache.commons.collections.map

Class CaseInsensitiveMap

public class CaseInsensitiveMap extends AbstractHashedMap implements Serializable, Cloneable

A case-insensitive Map.

As entries are added to the map, keys are converted to all lowercase. A new key is compared to existing keys by comparing newKey.toString().toLower() to the lowercase values in the current KeySet.

Null keys are supported.

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

Example:


  Map map = new CaseInsensitiveMap();
  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}.

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 java.util.Collections#synchronizedMap(Map). This class may throw exceptions when accessed by concurrent threads without synchronization.

Since: Commons Collections 3.0

Version: $Revision: 348007 $ $Date: 2005-11-21 22:52:57 +0000 (Mon, 21 Nov 2005) $

Author: Commons-Collections team

Constructor Summary
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 map)
Constructor copying elements from another map.
Method Summary
Objectclone()
Clones the map without cloning the keys or values.
protected ObjectconvertKey(Object key)
Overrides convertKey() from AbstractHashedMap to convert keys to lower case.

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 less than one

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 less than one IllegalArgumentException if the load factor is less than zero

CaseInsensitiveMap

public CaseInsensitiveMap(Map 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

clone

public Object clone()
Clones the map without cloning the keys or values.

Returns: a shallow clone

convertKey

protected Object convertKey(Object key)
Overrides convertKey() from AbstractHashedMap to convert keys to lower case.

Returns null if key is null.

Parameters: key the key convert

Returns: the converted key

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