Arithmetic Operation using AWT Frame with Event Delegation

import java.awt.Button;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.Label;
// author : www.raviroza.com
// date   : 27-Jan-2023, 8.25 am
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class ArithmaticOperation 
extends Frame
implements ActionListener
{
	Label l1,l2,lblResult;
	TextField txtNo1, txtNo2;
	Button btnAdd, btnSub, btnMul, btnDiv;
	
	public ArithmaticOperation() {
		// TODO Auto-generated constructor stub
		l1 = new Label("enter number 1 : ");
		l2 = new Label("enter number 2 : ");
		lblResult = new Label("0");
		
		txtNo1 = new TextField(3);
		txtNo2 = new TextField(3);
		
		btnAdd = new Button("+");
		btnSub = new Button("-");
		btnMul = new Button("*");
		btnDiv = new Button("/");
		
		setLayout(new FlowLayout());
		add(l1);  add(txtNo1);
		add(l2);  add(txtNo2);
		
		add(lblResult);
		
		add(btnAdd);  add(btnSub);
		add(btnMul);  add(btnDiv);
		
		btnAdd.addActionListener(this);
		btnSub.addActionListener(this);
		btnMul.addActionListener(this);
		btnDiv.addActionListener(this);
		
			
		setSize(500, 500);
		//validate();
		
		setVisible(true);
	}	
	public void actionPerformed(ActionEvent e) 
	{
		int a = Integer.parseInt(txtNo1.getText());
		int b = Integer.parseInt(txtNo2.getText());
		int c = 0;
		if(e.getSource() == btnAdd)		
		{
				c = a + b;			
		}		
		else if(e.getSource() == btnSub)
		{
				c = a - b;			
		}
		else if(e.getSource() == btnMul)
		{
				c = a * b;			
		}
		else if(e.getSource() == btnDiv)
		{
				c = a / b;			
		}							
		lblResult.setText ( Integer.toString(c));
	}
	public static void main(String[] args) 
	{
		new ArithmaticOperation();
	}
}