两个坐标之间的距离！

class XYPoint{
    double x;
    double y;
    public void setX(double x){
        this.x = x;
    }
    public void setY(double y){
        this.y = y;
    }
    public double getX(){
        return x;
    }
    public double getY(){
        return y;
    }
    public void getDistence(XYPoint p){
        double d = Math.sqrt((this.x-p.x)*(this.x-p.x)+(this.y-p.y)*(this.y-p.y));
        System.out.println(d);
    }
}

class Demo{
    public static void main(String[] args){
        XYPoint xy = new XYPoint();
        XYPoint xy1 = new XYPoint();
        xy.setX(1);
        xy.setY(1);
        xy1.setX(3);
        xy1.setY(3);
        xy.getDistence(xy1);
    }
}