JOptionPane Example In Java.♥

import javax.swing.JOptionPane;

public class JOptionPaneTest1 {
    public static void main(String[] args) {
        String ans;
        ans = JOptionPane.showInputDialog(null, "Speed in miles per hour?");
        double mph = Double.parseDouble(ans);
        double kph = 1.621 * mph;
        JOptionPane.showMessageDialog(null, "KPH = " + kph);

        System.exit(0);
    }
}

OUTPUT :