How to check if HashSet contains an element or not

In order to find out how many elements are in set, you can use the size() method:

 public int size()  

You can also use isEmpty() method to check if there is any element in given HashSet.

 public boolean isEmpty()   

Sample Program:

 import java.util.HashSet;  
 import java.util.Set;  
 /**  
  *   
  */  
 /**  
  * @author Dixit  
  *   
  */  
 public class HashSetSize {  
      /**  
       * @param args  
       */  
      public static void main(String[] args) {  
           Set set = new HashSet();  
           System.out.println("Before adding element");  
           System.out.println(set.size());  
           System.out.println(set.isEmpty());  
           set.add("a");  
           set.add("b");  
           System.out.println("After adding element");  
           System.out.println(set.size());  
           System.out.println(set.isEmpty());  
      }  
 }  

Output:  
 Before adding element  
 0  
 true  
 After adding element  
 2  
 false  

Happy Reading :)