jls4_8.java

public interface Colorable {
	void setColor(byte r, byte g, byte b);
}
class Point { int x, y; }
class ColoredPoint extends Point implements Colorable {
	byte r, g, b;
	public void setColor(byte rv, byte gv, byte bv) {
		r = rv; g = gv; b = bv;
	}
}
class Test {
	public static void main(String[] args) {
		Point p = new Point();
		ColoredPoint cp = new ColoredPoint();
		p = cp;
		Colorable c = cp;
	}
}