org.apache.commons.collections
Interface OrderedMap

All Superinterfaces:

IterableMap, java.util.Map

All Known Subinterfaces:

OrderedBidiMap, SortedBidiMap

All Known Implementing Classes:

AbstractLinkedMap, AbstractOrderedBidiMapDecorator, AbstractOrderedMapDecorator, AbstractSortedBidiMapDecorator, DualTreeBidiMap, LinkedMap, ListOrderedMap, LRUMap, SingletonMap, TreeBidiMap, UnmodifiableOrderedBidiMap, UnmodifiableOrderedMap, UnmodifiableSortedBidiMap

public interface OrderedMap
extends IterableMap

Defines a map that maintains order and allows both forward and backward iteration through that order.

Since:

Commons Collections 3.0

Version:

$Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $

Author:

Stephen Colebourne

Nested Class Summary

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

java.util.Map.Entry

Method Summary

java.lang.Object	firstKey() Gets the first key currently in this map.
java.lang.Object	lastKey() Gets the last key currently in this map.
java.lang.Object	nextKey(java.lang.Object key) Gets the next key after the one specified.
OrderedMapIterator	orderedMapIterator() Obtains an OrderedMapIterator over the map.
java.lang.Object	previousKey(java.lang.Object key) Gets the previous key before the one specified.

Methods inherited from interface org.apache.commons.collections.IterableMap

mapIterator

Methods inherited from interface java.util.Map

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

Method Detail

orderedMapIterator

OrderedMapIterator orderedMapIterator()

Obtains an OrderedMapIterator over the map.

A ordered map iterator is an efficient way of iterating over maps in both directions.

 BidiMap map = new TreeBidiMap();
 MapIterator it = map.mapIterator();
 while (it.hasNext()) {
   Object key = it.next();
   Object value = it.getValue();
   it.setValue("newValue");
   Object previousKey = it.previous();
 }
 

Returns:

a map iterator

firstKey

java.lang.Object firstKey()

Gets the first key currently in this map.

Returns:

the first key currently in this map

Throws:

java.util.NoSuchElementException - if this map is empty

lastKey

java.lang.Object lastKey()

Gets the last key currently in this map.

Returns:

the last key currently in this map

Throws:

java.util.NoSuchElementException - if this map is empty

nextKey

java.lang.Object nextKey(java.lang.Object key)

Gets the next key after the one specified.

Parameters:

key - the key to search for next from

Returns:

the next key, null if no match or at end

previousKey

java.lang.Object previousKey(java.lang.Object key)

Gets the previous key before the one specified.

Parameters:

key - the key to search for previous from

Returns:

the previous key, null if no match or at start