HashSet add() Method in Java

The Java.util.HashSet.add() method in Java HashSet is used to add a specific element into a HashSet. This method will add the element only if the specified element is not present in the HashSet else the function will return False if the element is already present in the HashSet.

Syntax:

Hash_Set.add(Object element)

Parameters: The parameter element is of the type HashSet and refers to the element to be added to the Set.

Return Value: The function returns True if the element is not present in the HashSet otherwise False if the element is already present in the HashSet.

Below program illustrate the Java.util.HashSet.add() method:

// Java code to illustrate add()
import java.io.*;
import java.util.HashSet;

public class HashSetDemo {
    public static void main(String args[])
    {
        // Creating an empty HashSet
        HashSet<String> set = new HashSet<String>();

        // Use add() method to add elements into the Set
        set.add("Welcome");
        set.add("To");
        set.add("Geeks");
        set.add("4");
        set.add("Geeks");

        // Displaying the HashSet
        System.out.println("HashSet: " + set);
    }
}

Output:

HashSet: [4, Geeks, Welcome, To]