Program Untuk Menghitung Luas Lingkaran ( Java Swing )

import javax.swing.*;
public class lingkaran
{
public static void main (String anjing [])
{
String input=JOptionPane.showInputDialog("masukan Nilai jari-jari ");//input secara mesej
double r = Double.parseDouble(input);

double l = 3.14*(r*r);
double k = 6.28*r;


JOptionPane.showMessageDialog(null,"Luas lingkaran = "+l,"Info",JOptionPane.INFORMATION_MESSAGE);//output secara mesej
JOptionPane.showMessageDialog(null,"keliling lingkaran ="+k,"Info",JOptionPane.INFORMATION_MESSAGE);//output secara mesej
System.exit(0);
}}