Learning some swing operations

I'm working on a program that is using swing. In the getDouble method, I believe what I want to do is:

1. allow for user input

2. capture the user input

I'm not sure how to do this in this program:

import javax.swing.*; // Package containing JOptionPane

public class KmToMilesMethods {

//========================================================= constants

private static final double MILES_PER_KILOMETER = 0.621;

//============================================================== main

public static void main(String[] args) {

double kms = getDouble("Enter number of kilometers.");

double miles = convertKmToMi(kms);

displayString(kms + " kilometers is " + miles + " miles.");

}

//===================================================== convertKmToMi

// Conversion method - kilometers to miles.

private static double convertKmToMi(double kilometers) {

double miles = kilometers * MILES_PER_KILOMETER;

return miles;

// added two Java lines above

}

//========================================================= getDouble

// I/O convenience method to read a double value.

private static double getDouble(String prompt) {

//three Java lines go here

}

//===================================================== displayString

// I/O convenience method to display a string in dialog box.

private static void displayString(String output) {

JOptionPane.showMessageDialog(null, output);

**************

So far I've tried to enter a showInputDialog using a string, double, kms or number and I'm getting errors that I can't convert string to double or that I can't resolve one of the variables "kms"

Any help in steering my brain down the right thought path is appreciated.

Dansing

[1871 byte] By [dansinga] at [2007-11-27 0:20:57]