java - Why do I receive the error "This method must return a result of type ..."?

Question

Can anyone see why I would receive the error "This method must return a result of type Card", when I clearly returns that variable "card" which is of type Card?

public Card playCard(int id){
    int i = 0;
    for (Card element : hand){
        if (i <= hand.size())
        {           
            if (element.getID() == id)
            {
                Card card = hand.get(i);
                hand.remove(i);
                return card;
            }
            else
            {
                i++;
            }

        }
        else
        {
            throw new NullPointerException("Card does not exist in     hand");
        }
    }
}

Answer 1

Your method doesn't return anything except in one possible scenario. It has to return something (or throw an exception) in all possible scenarios.

I think you meant to do this:

public Card playCard(int id){

    for (Card element : hand) {
        if (element.getID() == id) {
            return element;
        }
    }
    throw new SomeAppropriateException("Card does not exist in     hand");
}

...but I'm guessing a bit (as I don't know what hand is, but it looked a lot like a List). That code will always either execute the return statement or throw an exception, there's no way to get to the end of the method without one of those things happening.

Note that throwing a NullPointerException for a condition that isn't caused by a null pointer is a Bad Idea^(tm). (It's also best to be consistent in where you put your { and }.)