Calculator

import java.awt.*;
import java.awt.event.*;
class Calculator implements ActionListener
{
 Frame f=new Frame();
 Label l1 = new Label("First Number");
 Label l2 = new Label("Second Number");
 Label l3 = new Label("Result");
 TextField t1= new TextField();
 TextField t2= new TextField();
 TextField t3= new TextField();
 Button b1 = new Button("Add");
 Button b2 = new Button("Sub");
 Button b3 = new Button("Mul");
 Button b4 = new Button("Div");
 Button b5 = new Button("Cancel");
 Calculator()
 {
 l1.setBounds(50,100,100,20);
 l2.setBounds(50,140,100,20);
 l3.setBounds(50,180,100,20);
 t1.setBounds(200,100,150,20);
 t2.setBounds(200,140,150,20);
 t3.setBounds(200,180,150,20);
 b1.setBounds(50,250,70,20);
 b2.setBounds(110,250,70,20);
 b3.setBounds(170,250,70,20);
 b4.setBounds(230,250,70,20);
 b5.setBounds(290,250,70,20);
 f.add(l1);
 f.add(l2);
 f.add(l3);
 f.add(t1);
 f.add(t2);
 f.add(t3);
 f.add(b1);
 f.add(b2);
 f.add(b3);
 f.add(b4);
 f.add(b5);
 b1.addActionListener(this);
 b2.addActionListener(this);
 b3.addActionListener(this);
 b4.addActionListener(this);
 b5.addActionListener(this);
 f.setLayout(null);
 f.setVisible(true);
 f.setSize(400,350);
}
public void actionPerformed(ActionEvent e)
{
 int n1 = Integer.parseInt(t1.getText());
 int n2 = Integer.parseInt(t2.getText());
 if(e.getSource()==b1)
 {
  t3.setText(String.valueOf(n1+n2));
 }
 if(e.getSource()==b2)
 {
  t3.setText(String.valueOf(n1-n2));
 }
 if(e.getSource()==b3)
 {
  t3.setText(String.valueOf(n1*n2));
 }
 if(e.getSource()==b4)
 {
  t3.setText(String.valueOf(n1/n2));
 }
 if(e.getSource()==b5)
 {
  System.exit(0);
 }
}
public static void main(String [] args)
{
  new Calculator();
 }
}