org.apache.commons.collections
Interface MultiMap

All Superinterfaces:

Map

All Known Implementing Classes:

MultiHashMap

public interface MultiMap

extends Map

Defines a map that holds a collection of values against each key.

A MultiMap is a Map with slightly different semantics. Putting a value into the map will add the value to a Collection at that key. Getting a value will always return a Collection, holding all the values put to that key. This implementation uses an ArrayList as the collection.

For example:

 MultiMap mhm = new MultiHashMap();
 mhm.put(key, "A");
 mhm.put(key, "B");
 mhm.put(key, "C");
 Collection coll = (Collection) mhm.get(key);

coll will be a list containing "A", "B", "C".

Since:

Commons Collections 2.0

Version:

$Revision: 1.10 $ $Date: 2004/01/14 21:43:04 $

Author:

Christopher Berry, James Strachan, Stephen Colebourne

Method Summary

Object

remove(Object key, Object item) Removes a specific value from map.

Methods inherited from interface java.util.Map

clear, containsKey, containsValue, entrySet, equals, get, hashCode, isEmpty, keySet, put, putAll, remove, size, values

Method Detail

remove

public Object remove(Object key,
                     Object item)

Removes a specific value from map.

The item is removed from the collection mapped to the specified key.

Parameters:

key - the key to remove from

item - the item to remove

Returns:

the value removed (which was passed in)