Java HashSet class

• uses hashtable to store the elements.It extends AbstractSet class and implements Set interface.
• contains unique elements only.

Difference between List and Set:

List can contain duplicate elements whereas Set contains unique elements only.

Hierarchy of HashSet class:

Example of HashSet class:

1.    import java.util.*;  

2.    class TestCollection9{  

3.     public static void main(String args[]){  

4.       

5.      HashSet<String> al=new HashSet<String>();  

6.      al.add("Ravi");  

7.      al.add("Vijay");  

8.      al.add("Ravi");  

9.      al.add("Ajay");  

10.   

11.   Iterator<String> itr=al.iterator();  

12.   while(itr.hasNext()){  

13.    System.out.println(itr.next());  

14.   }  

15.  }  

16. }  

Output:Ajay

       Vijay

       Ravi