JOptionPaneTest

// File: joptionpane-examples/JOptionPaneTest1.java
// Description: JOptionPane example.
// Author: Fred Swartz
// Date:   31 Jan 2005

import javax.swing.JOptionPane;

public class JOptionPaneTest1 {
    public static void main(String[] args) {
        String ans;
        ans = JOptionPane.showInputDialog(null, "Speed in miles per hour?");
	if (ans==null) System.exit(0);
	try {
        double mph = Double.parseDouble(ans);
        double kph = 1.621 * mph;
        JOptionPane.showMessageDialog(null, "KPH = " + kph);
	}
	catch (NumberFormatException e) {
	System.out.println("Please enter a valid number"); }

        System.exit(0);
    }
}