//Main.java

abstract class Shape
{

    protected Point position;

    abstract double computeArea();

    public Point getPosition()
    {
        return this.position;
    }

    public void setPosition(Point position)
    {
        this.position = position;
    }

    public void movePositionRelative(Point position)
    {
        double x = this.position.getX() + position.getX();
        double y = this.position.getY() + position.getY();

        this.position.setX(x);
        this.position.setY(y);
    }
}

public class Main
{
    public static void main(String[] args)
    {
        Shape shape = new Shape();
        //...
    }
}