NavigableMap

import java.util.Iterator;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.TreeMap;
//from j a v a  2  s  .  c  o  m
public class Main {
  public static void main(String[] args) {
    NavigableMap<String, Integer> navigableMap = new TreeMap<String, Integer>();
    String[] letters = { "a", "b", "c" };
    int[] ints = { 3, 2, 1 };
    for (int i = 0; i < letters.length; i++){
      navigableMap.put(letters[i], ints[i]);
    }
    System.out.println("Map = " + navigableMap);
    NavigableSet<String> ns = navigableMap.navigableKeySet();
    Iterator iter = ns.iterator();
    while (iter.hasNext()){
      System.out.print(iter.next() + " ");
    }
    System.out.println();
    ns = navigableMap.descendingKeySet();
    iter = ns.iterator();
    while (iter.hasNext()){
      System.out.print(iter.next() + " ");
    }      
    System.out.println();
    System.out.println("First entry = " + navigableMap.firstEntry());
    System.out.println("Last entry = " + navigableMap.lastEntry());
    System.out.println("Entry < a is " + navigableMap.lowerEntry("a"));
    System.out.println("Entry > c is " + navigableMap.higherEntry("c"));
    System.out.println("Poll first entry: " + navigableMap.pollFirstEntry());
    System.out.println("Map = " + navigableMap);
    System.out.println("Poll last entry: " + navigableMap.pollLastEntry());
    System.out.println("Map = " + navigableMap);
  }
}

Map = {a=3, b=2, c=1}// jav  a  2  s.co m
a b c 
c b a 
First entry = a=3
Last entry = c=1
Entry < a is null
Entry > c is null
Poll first entry: a=3
Map = {b=2, c=1}
Poll last entry: c=1
Map = {b=2}