import javax.swing.*;
import java.awt.*;
import java.util.*;
import java.text.*;

public class GreatCircle extends JApplet {

    public  void init () {

        DecimalFormat d1, d2;
	d1 = new DecimalFormat ("0.0");
	d2 = new DecimalFormat ("0.00");
	double latitude1, longitude1, latitude2, longitude2;
	double degreesDistance, distance;
	final double RADIUS=6372.8;  //assuming spherical Earth
	StringTokenizer twoDoubles;
	
	String input;
	input = JOptionPane.showInputDialog("Point 1 latitude and longitude in degrees (negative for South and West)");
	twoDoubles = new StringTokenizer(input);
	latitude1 = Double.parseDouble(twoDoubles.nextToken());
	longitude1 = Double.parseDouble(twoDoubles.nextToken());

	input = JOptionPane.showInputDialog("Point 2 latitude and longitude in degrees (negative for South and West)");
	twoDoubles = new StringTokenizer(input);
	latitude2 = Double.parseDouble(twoDoubles.nextToken());
	longitude2 = Double.parseDouble(twoDoubles.nextToken());

	degreesDistance = Math.toDegrees(Math.acos(
		                           Math.sin(Math.toRadians(latitude1))*Math.sin(Math.toRadians(latitude2)) +
		                           Math.cos(Math.toRadians(latitude1))*Math.cos(Math.toRadians(latitude2))*
		                         	Math.cos(Math.toRadians(Math.abs(longitude1-longitude2)))));
	distance = RADIUS * Math.toRadians(degreesDistance);

	JOptionPane.showMessageDialog(null, "Distance between "+latitude1+","+longitude1+" and "+
		                                                 latitude2+","+longitude2+"\n"+
		                            d1.format(degreesDistance)+"\u00B0  "+
		                            d1.format(distance)+" km  "+d1.format(distance*.6214)+" mi");
    }
}