Package org.apache.commons.collections

Interface OrderedMap

All Superinterfaces:
IterableMap, 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 14:33:15 +0200 (Thu, 10 Apr 2008) $
Author:
Stephen Colebourne

  • Method Details

    • 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

      Object firstKey()
      Gets the first key currently in this map.
      Returns:
      the first key currently in this map
      Throws:
      NoSuchElementException - if this map is empty

    • lastKey

      Object lastKey()
      Gets the last key currently in this map.
      Returns:
      the last key currently in this map
      Throws:
      NoSuchElementException - if this map is empty

    • nextKey

      Object nextKey(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

      Object previousKey(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