The equals() method of java.util.Set class is used to verify the equality of an Object with a Set and compare them. The method returns true if the size of both the sets are equal and both contain the same elements.
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 Set  import java.util.*;  public class GFG {    public static void main(String[] argv)    {          // Creating object of Set        Set<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 Set: "                           + arrset1);          // Creating another object of Set        Set<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 Set: "                           + arrset2);          // comparing first Set to another        // using equals() method        boolean value = arrset1.equals(arrset2);          // print the value        System.out.println("Are both set equal? "                           + value);    }} |
Output:
First Set: [A, B, C, D, E] Second Set: [A, B, C, D, E] Are both set equal? true
Example 2:
// Java program to demonstrate equals()// method of Set  import java.util.*;  public class GFG1 {    public static void main(String[] argv)    {          // Creating object of Set        Set<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 Set: " + arrset1);          // Creating another object of Set        Set<Integer> arrset2 = new HashSet<Integer>();          // Populating arrset2        arrset2.add(10);        arrset2.add(20);        arrset2.add(30);          // print arrset2        System.out.println("Second Set: " + arrset2);          // comparing first Set to another        // using equals() method        boolean value = arrset1.equals(arrset2);          // print the value        System.out.println("Are both set equal? "                           + value);    }} |
Output:
First Set: [50, 20, 40, 10, 30] Second Set: [20, 10, 30] Are both set equal? false
Reference: https://docs.oracle.com/javase/7/docs/api/java/util/Set.html#equals(java.lang.Object)
