@Override

The @Override you can put on methods to have Java check that you are properly overriding them is an annotation.

There's not much else to say besides "hey, thats what that was!" but I think its worth noting.

interface Num {
    boolean odd();

    boolean even();
}

class IntNum implements Num {
    final int x;

    IntNum(int x) {
        this.x = x;
    }

    @Override // This is an annotation?
    public boolean odd() {
        return x % 2 != 0;
    }

    @Override // Always has been.
    public boolean even() {
        return !odd();
    }
}