Java: check for null or allow exception handling

Question

I\'m wondering about the cost of using a try/exception to handle nulls compared to using an if statement to check for nulls first.

To provide more information. There

Answer 1

If passing null argument is an exceptional case, then I'd throw a NullPointerException.

public Result calculate(Input input) {
    if (input == null) throw new NullPointerException("input");
    // ...
}

If passing null is an allowed case, then I'd skip the calculation and eventually return null. But that makes in my opinion less sense. Passing null in first instance would seem a bug in the calling code.

Whatever way you choose, it should be properly documented in the Javadoc to avoid surprises for the API user.