Java: Geometry: great circle distance

package chapter4_4_2;
import java.util.Scanner;
/**
 *
 * @author Siavash Bakhshi
 */
public class Chapter4_4_2 {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // Add Scanner to read input from user
        Scanner input = new Scanner(System.in);
        // text to prompt to user asking to enter a number
        System.out.print("Enter point 1 (latitude and longitude) in degrees: ");
        String xy1in = input.nextLine();
        System.out.print("Enter point 2 (latitude and longitude) in degrees: ");
        String xy2in = input.nextLine();
        String[] xy1 = xy1in.split(",");
        String[] xy2 = xy2in.split(",");
        //Declare Parameters
        double radius = 6371.01;
        double x1 = Math.toRadians(Double.parseDouble(xy1[0]));
        double y1 = Math.toRadians(Double.parseDouble(xy1[1]));
        double x2 = Math.toRadians(Double.parseDouble(xy2[0]));
        double y2 = Math.toRadians(Double.parseDouble(xy2[1]));
         //The great circle distance formula:      
        double d = radius * Math.acos((Math.sin(x1) * Math.sin(x2)) + (Math.cos(x1) * Math.cos(x2)) * (Math.cos(y1 - y2)));
        System.out.println("The distance between the two points is " + d + "km");
    }
    
}