Java HashSet isEmpty() Method

---

---

Description

The Java HashSet isEmpty() method is used to check if this set contains no elements.

Declaration

Following is the declaration for java.util.HashSet.isEmpty() method.

public boolean isEmpty()

Parameters

NA

Return Value

The method call returns 'true' if this set contains no elements.

Exception

NA

Checking if HashSet of Integers is Empty or Not

The following example shows the usage of Java HashSet isEmpty() method to check if HashSet is empty or not. We've created a HashSet object of Integer. Then few entries are added using add() method and then set status is checked and printed using isEmpty() method. Now set is cleared using clear() method and then again set status is checked and printed using isEmpty() method.

package com.tutorialspoint;

import java.util.HashSet;

public class HashSetDemo {
   public static void main(String args[]) {
      
      // create hash set
      HashSet <Integer> newset = new HashSet <>();      

      // populate hash set
      newset.add(1); 
      newset.add(2);
      newset.add(3);  

      // checking elements in hash set
      System.out.println("Hash set is empty: "+ newset.isEmpty());

      // clear the set
      newset.clear();

      // print the set
      System.out.println("Hash set is empty after clearing: "+ newset.isEmpty());
   }    
}

Output

Let us compile and run the above program, this will produce the following result.

Hash set is empty: false
Hash set is empty after clearing: true

Checking if HashSet of Strings is Empty or Not

The following example shows the usage of Java HashSet isEmpty() method to check if HashSet is empty or not. We've created a HashSet object of String. Then few entries are added using add() method and then set status is checked and printed using isEmpty() method. Now set is cleared using clear() method and then again set status is checked and printed using isEmpty() method.

package com.tutorialspoint;

import java.util.HashSet;

public class HashSetDemo {
   public static void main(String args[]) {
      
      // create hash set
      HashSet <String> newset = new HashSet <>();      

      // populate hash set
      newset.add("Learning"); 
      newset.add("Easy");
      newset.add("Simply");  

      // checking elements in hash set
      System.out.println("Hash set is empty: "+ newset.isEmpty());

      // clear the set
      newset.clear();

      // print the set
      System.out.println("Hash set is empty after clearing: "+ newset.isEmpty());
   }    
}

Output

Let us compile and run the above program, this will produce the following result.

Hash set is empty: false
Hash set is empty after clearing: true

Checking if HashSet of Objects is Empty or Not

The following example shows the usage of Java HashSet isEmpty() method to check if HashSet is empty or not. We've created a HashSet object of Student objects. Then few entries are added using add() method and then set status is checked and printed using isEmpty() method. Now set is cleared using clear() method and then again set status is checked and printed using isEmpty() method.

package com.tutorialspoint;

import java.util.HashSet;

public class HashSetDemo {
   public static void main(String args[]) {
      
      // create hash set
      HashSet <Student> newset = new HashSet <>();      

      // populate hash set
      newset.add(new Student(1, "Julie")); 
      newset.add(new Student(2, "Robert"));
      newset.add(new Student(3, "Adam"));	  

      // checking elements in hash set
      System.out.println("Hash set is empty: "+ newset.isEmpty());

      // clear the set
      newset.clear();

      // print the set
      System.out.println("Hash set is empty after clearing: "+ newset.isEmpty());
   }    
}
class Student {
   int rollNo;
   String name;

   Student(int rollNo, String name){
      this.rollNo = rollNo;
      this.name = name;
   }

   @Override
   public String toString() {
      return "[ " + this.rollNo + ", " + this.name + " ]";
   }
}

Output

Let us compile and run the above program, this will produce the following result.

Hash set is empty: false
Hash set is empty after clearing: true