class GenericsTester {
   public static void main(String[] args) {

    Box<Cake> cakeBox = new Box<>();
    Box<Pie> pieBox = new Box<>();
    Box<Tart> tartBox = new Box<>();

    cakeBox.put(new Cake());
    pieBox.put(new Pie());
    tartBox.put(new Tart());

   }
}

class Box<T> {
    private T t;

    public void put(T t) {
        this.t = t;
        }

    public T get() {
        return t;
    }
}