Java HashSet size() Method

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Description

The Java HashSet size() method is used to get the number of elements in this set.

Declaration

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

public int size()

Parameters

NA

Return Value

The method call returns the number of elements in this set.

Exception

NA

Getting Size of the HashSet of Integers Example

The following example shows the usage of Java HashSet size() method to print the count of entries of the HashSet. We've created a HashSet object of Integer. Then few entries are added using add() method and then set size is printed using size() 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);  

      // print the size of the set
      System.out.println("Hash set size: "+ newset.size());
   }    
}

Output

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

Hash set size: 3

Getting Size of the HashSet of Strings Example

The following example shows the usage of Java HashSet size() method to print the count of entries of the HashSet. We've created a HashSet object of String. Then few entries are added using add() method and then set size is printed using size() 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");  

      // print the size of the set
      System.out.println("Hash set size: "+ newset.size());
   }    
}

Output

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

Hash set size: 3

Getting Size of the HashSet of Objects Example

The following example shows the usage of Java HashSet size() method to print the count of entries of the HashSet. We've created a HashSet object of Student objects. Then few entries are added using add() method and then set size is printed using size() 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"));	  

      // print the size of the set
      System.out.println("Hash set size: "+ newset.size());
   }    
}
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 size: 3