Advanced Java Programming - Old Questions

2. Write a program using swing components to add two numbers. Use text fields for inputs and output. Your program should display the result when the user presses a button. (10)

import javax.swing.*;

import java.awt.*;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

class Addition extends JFrame implements ActionListener    //implement listener interface

{

 JLabel l1, l2;

 JTextField t1, t2, t3;

 JButton b1; 

 public Addition() 

{

  l1 = new JLabel("First Number:");

  l1.setBounds(20, 10, 100, 20);    //x, y, width, height

  t1 = new JTextField(10);

  t1.setBounds(120, 10, 100, 20);

  l2 = new JLabel("Second Number:");

  l2.setBounds(20, 40, 100, 20);    

  t2 = new JTextField(10);

  t2.setBounds(120, 40, 100, 20);

  b1 = new JButton("Sum");

  b1.setBounds(20, 70, 80, 20);

  t3 = new JTextField(10);

  t3.setBounds(120, 70, 100, 120);

  add(l1);

  add(t1);

  add(l2);

  add(t2);

  add(b1);

  add(t3);

  b1.addActionListener(this);    //Registering event

  setSize(400,300);

  setLayout(null);

  setVisible(true);

  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  

}

 @Override

 public void actionPerformed(ActionEvent e)    //Handle Event

 {

    if(e.getSource()==b1){

        int num1 = Integer.parseInt(t1.getText()); 

        int num2 = Integer.parseInt(t2.getText()); 

        int sum = num1 + num2;

        t3.setText(String.valueOf(sum));

   }

 public static void main(String args[])

 {

    new Addition();

 }

}