HashSet equals() method in Java with Example

The equals() method of java.util.HashSet class is used verify the equality of an Object with a HashSet and compare them. The list returns true only if both HashSet contains same elements, irrespective of order.

Syntax:

public boolean equals(Object o)

Parameters: This method takes the object o as a parameter to be compared for equality with this set.

Returns Value: This method returns true if the specified object is equal to this set.

Below are the examples to illustrate the equals() method.

Example 1:

// Java program to demonstrate equals()
// method of HashSet

import java.util.*;

public class GFG {
    public static void main(String[] argv)
    {

        // Creating object of HashSet<String>
        HashSet<String>
            arrset1 = new HashSet<String>();

        // Populating arrset1
        arrset1.add("A");
        arrset1.add("B");
        arrset1.add("C");
        arrset1.add("D");
        arrset1.add("E");

        // print arrset1
        System.out.println("First HashSet: "
                           + arrset1);

        // Creating another object of HashSet<String>
        HashSet<String>
            arrset2 = new HashSet<String>();

        // Populating arrset2
        arrset2.add("A");
        arrset2.add("B");
        arrset2.add("C");
        arrset2.add("D");
        arrset2.add("E");

        // print arrset2
        System.out.println("Second HashSet: "
                           + arrset2);

        // comparing first HashSet to another
        // using equals() method
        boolean value
            = arrset1.equals(arrset2);

        // print the value
        System.out.println("Are both set equal: "
                           + value);
    }
}

Output:

First HashSet: [A, B, C, D, E]
Second HashSet: [A, B, C, D, E]
Are both set equal: true

Example 2:

// Java program to demonstrate equals()
// method of HashSet

import java.util.*;

public class GFG1 {
    public static void main(String[] argv)
    {

        // Creating object of HashSet
        HashSet<Integer>
            arrset1 = new HashSet<Integer>();

        // Populating arrset1
        arrset1.add(10);
        arrset1.add(20);
        arrset1.add(30);
        arrset1.add(40);
        arrset1.add(50);

        // print arrset1
        System.out.println("First HashSet: "
                           + arrset1);

        // Creating another object of HashSet
        HashSet<Integer>
            arrset2 = new HashSet<Integer>();

        // Populating arrset2
        arrset2.add(10);
        arrset2.add(20);
        arrset2.add(30);

        // print arrset2
        System.out.println("Second HashSet: "
                           + arrset2);

        // comparing first HashSet to another
        // using equals() method
        boolean value = arrset1.equals(arrset2);

        // print the value
        System.out.println("Are both set equal: "
                           + value);
    }
}

Output:

First HashSet: [50, 20, 40, 10, 30]
Second HashSet: [20, 10, 30]
Are both set equal: false