Java Notes

Dialog I/O: Kilometers to Miles with Method

This program is the same as Example: Dialog: Kilometers to Miles, but with one change: the conversion of kilometers to miles is done in a method.

  1 
  2 
  3 
  4 
  5 
  6 
  7 
  8 
  9 
 10 
 11 
 12 
 13 
 14 
 15 
 16 
 17 
 18 
 19 
 20 
 21 
 22 
 23 
 24 
 25 
 26 
 27 
 28 
 29 
 30 
 31 
 32 
 33 
 34 
 35 
// File   : intro-dialog/KmToMilesMethod.java
// Purpose: Convert kilometers to miles using a method.  JOptionPane IO.
// Author : Michael Maus
// Date   : 28 Oct 2004

import javax.swing.*;

public class KmToMilesMethod {

    //================================================================= main
    public static void main(String[] args) {
        //... Local variables
        String kmStr;    // String km before conversion to double.
        double km;       // Number of kilometers.
        double mi;       // Number of miles.

        //... Input
        kmStr = JOptionPane.showInputDialog(null, "Enter kilometers.");
        km = Double.parseDouble(kmStr);

        //... Computation
        mi = convertKmToMi(km);                                     //Note 1

        //... Output
        JOptionPane.showMessageDialog(null, km + " kilometers is "
                                          + mi + " miles.");
    }

    //========================================================= convertKmToMi
    public static double convertKmToMi(double kilometers) {
        // Assume there are 0.621 miles in a kilometer.
        double miles = kilometers * 0.621;
        return miles;
    }
}

Notes

Note 1: Call a method to do the conversion. Altho this method is trivial, just a multiplication, it is good practice to separate the "model" or "logic" of the program from user interface. As programs become larger, this separation becomes essential.