NavigableMap

What is NavigableMap in Java 6 ?
NavigableMap in Java 6 is an extension of SortedMap like TreeMap which provides convenient navigation method like lowerKey, floorKey, ceilingKey and higherKey.it also provide ways to create a Sub Map from existing Map e.g. headMap whose keys are less than specified key, tailMap whose keys are greater than specified key and a subMap which is strictly contains keys which falls between specified toKey and fromKey.These methods also provides a boolean to include specified key or not.

import java.util.NavigableMap;
import java.util.TreeMap;

/**
 *
 * What is NavigableMap in Java. 
 * How to use NavigableMap in Java.
 * NavigableMap provides important features - navigation methods
 * like lowerKey(), floorKey, ceilingKey() and higherKey().
 * There Entry counterpart and methods to create subMap e.g. headMap(), tailMap()
 * and subMap().
 *
 */
public class NavigableMapEx {

    public static void main(String args[]) {
     
        //NavigableMap extends SortedMap to provide useful navigation methods
        NavigableMap navigableMap = new TreeMap();
             
        navigableMap.put("BritneySpears", "I go through life like a karate kid");
        navigableMap.put("AnnePackard", "Nothing happens without risk");
        navigableMap.put("WillSmith", "Life is lived on the edge");
        navigableMap.put("Cinderella", "Live like there is no midnight");
        
        System.out.println("SorteMap:"+ navigableMap);
     
        //lowerKey returns key which is less than specified key
        System.out.println("lowerKey:"+ navigableMap.lowerKey("Cinderella"));
     
        //floorKey returns key which is less than or equal to specified key
        System.out.println("floorKey:"+ navigableMap.floorKey("AnnePackard"));
     
        //ceilingKey returns key which is greater than or equal to specified key
        System.out.println("ceilingKey:"+ navigableMap.ceilingKey("BritneySpears"));
     
        //higherKey returns key which is greater specified key
        System.out.println("higherKey:"+ navigableMap.higherKey("BritneySpears"));
     
     
        //It also provides useful method to create subMap from existing Map 
        //e.g. tailMap, headMap and subMap
     
        //headMap - returns NavigableMap whose key is less than specified
        //param: Key, boolean : inclusive
        NavigableMap headMap = navigableMap.headMap("Cinderella", false);
        System.out.println("headMap created form navigableMap : " + headMap);
             
        //tailMap - returns NavigableMap whose key is greater than specified
        NavigableMap tailMap = navigableMap.tailMap("BritneySpears", false);
        System.out.println("tailMap created form navigableMap : " + tailMap);
     
        //subMap - return NavigableMap from toKey to fromKey
        NavigableMap subMap = 
          navigableMap.subMap("AnnePackard", false,"WillSmith", false);
        System.out.println("subMap created form navigableMap : " + subMap);
    }
}