Alternate version of this xkcd comic: http://xkcd.com/1188

gistfile1.java

/**
 * Alternate version of this xkcd comic: http://xkcd.com/1188
 * 
 * My inner nitpicker was bugged by the fact that the comic isn't actually 
 * using the throw-catch exception mechanism to throw the ball over to the 
 * target, which I thought was the whole point. 
 * What actually happens is this: the parent throws the ball, catches it 
 * himself and then just passes it to the child (as a parameter)... which looks 
 * kinda silly when picturing it :) So I had to rewrite the thing such that 
 * it's a proper game of play catch.. 
 */
class Ball extends Throwable {}

class Person{
	public Person target = null;
	public Ball ball = null;

	public void giveMeYourBestShot() {
		try {
			target.hereItComes();
		} catch (Ball b) {
			ball = b;
			target.giveMeYourBestShot();
		}
	}

	public void hereItComes() throws Ball {
		Ball b = ball;
		ball = null;
		throw b;
	}

	public static void main(String[] args) {
		Person parent = new Person();
		Person child = new Person();
		parent.target = child;
		child.target = parent;
		parent.ball = new Ball();
		child.giveMeYourBestShot();
	}
}