public class Punkt2D {
    double x;
    double y;

    public Punkt2D(){
        x=0;
        y=0;
    }
    public Punkt2D(double x,double y){
        this.x=x;
        this.y=y;
    }
    public void setXY(double x,double y){
        this.x=x;
        this.y=y;
    }
    public double getX(){
        return this.x;
    }
    public double getY(){
        return this.y;
    }
    public double abstand(Punkt2D d){
        //satz von Phytagoras
        return Math.sqrt(quadrat(this.x-d.getX()) + quadrat(this.y-d.getY()));
    }
    private double quadrat(double d){
        return d*d;
    }
}