Analytic geometry

package math;
import java.math.*;
import java.util.Scanner;
import java.lang.*;
@SuppressWarnings("unused")
public class Math extends Globals {
    public static void main(String[] args){
        Math math = new Math();

        Scanner userInput = new Scanner(System.in);

        System.out.println("Var vänlig skriv in x1 och x2, följt av y1 och y2");
        System.out.println("=================================================");

        System.out.print("X1:");
        int x1 = userInput.nextInt();

        System.out.print("X2:");
        int x2 = userInput.nextInt();

        System.out.print("Y1:");
        int y1 = userInput.nextInt();

        System.out.print("Y2:");
        int y2 = userInput.nextInt();

        if(x1 > x2 && y1 > y2)
            z =  true;
        else
            z = false;

        double x3 = x1*x1;

        double x4 = x2*x2;

        double y3 = y1*y1;

        double y4 = y2*y2;


        if(z == true){

            double d2;
            d2 = (x3 - x4) + (y3 - y4);

            double d1;
            d1 = Math.sqrt(d2);

            System.out.println("The distance is: " + d1);
        }
        else{
            d2 = (x4 - x3) + (y4 - y3);

            d1 = Math.sqrt(d2);
            System.out.println("The distance is: " + d1);
        }

    }
    private static double sqrt(double d2) {
        // TODO Auto-generated method stub
        return 0;
    }
}