3. Swing Example

import javax.swing.*;

public class SwingExample {

    public static void main(String args[]){
        String n1 = JOptionPane.showInputDialog("1st number: ");
        String n2 = JOptionPane.showInputDialog("2nd number: ");
        int n11 = Integer.parseInt(n1);
        int n22 = Integer.parseInt(n2);
        int n = n11 + n22;
        JOptionPane.showMessageDialog(null, "The sum is " + n, "Adding two numbers", JOptionPane.PLAIN_MESSAGE);
    }
}