public class MutablePointMI {
    private MutableInteger x, y;

    public MutablePointMI(int x, int y) {
	this.x = new MutableInteger(x);
	this.y = new MutableInteger(y);
    }

    void setX(int v) { x.set(v); }
    void setY(int v) { y.set(v); }

    int getX() { return x.get(); }
    int getY() { return y.get(); }

    // This method is complicated because we have to make sure that
    // the X and Y values we compare are consistent---that a mutation
    // does not occur after retrieving one integer but before
    // retrieving the other
    public boolean equals(Object o) {
	if (o instanceof MutablePointMI) {
	    MutablePointMI p = (MutablePointMI)o;
	    int px, py;
	    synchronized (p) {
		px = p.getX();
		py = p.getY();
	    }
	    synchronized (this) {
		return (px == getX() && py == getY());
	    }
	}
	return false;
    }
}