Le code Java suivant se compile correctement :

abstract class GraphicObject {
    private int x, y;
    public void moveTo(int newX, int newY) {
        this.x = newX;
        this.y = newY;
    }
    public abstract void draw();
}
abstract class Circle extends GraphicObject {
    private java.awt.Point radius;
    public void draw() {
        // draw the circle...
    }
}