HashSet TreeSet

import java.util.TreeSet;
import java.util.Iterator;


public class TreeSetDemo {  
   public static void main(String[] args) {  
       TreeSet<String>  has=new TreeSet<String>();  
       has.add("1");  
       has.add("1");  
       has.add("2");  
       has.add("3");  
       has.add("4");  
       has.add("2");  
        Iterator<String>  it=has.iterator();   
        while (it.hasNext()) {  
            System.out.println(it.next());  
              
        }
    } 
} 
/*
---------- java ----------
1
2
3
4

Output completed (0 sec consumed) - Normal Termination
*/

 

import java.util.HashSet;
import java.util.Iterator;


public class HashSetDemo {  
   public static void main(String[] args) {  
       HashSet<String>  has=new HashSet<String>();  
       has.add("1");  
       has.add("1");  
       has.add("2");  
       has.add("3");  
       has.add("4");  
       has.add("2");  
        Iterator<String>  it=has.iterator();   
        while (it.hasNext()) {  
            System.out.println(it.next());  
              
        }
    } 
} 
/*
---------- java ----------
3
2
1
4

Output completed (0 sec consumed) - Normal Termination
*/