Is there an beautiful way to assert pre-conditions in Java methods?

Question

A lot of my functions have a whole load of validation code just below the declarations:

if ( ! (start < end) ) {
    throw new IllegalStateException( \"S         


        

Answer 1

You might be able to do this with annotation and aspect orientated programming.

I would use IllegalArgumentException if an argument combination is not legal. I would use IllegalStateException is in a state which prevents the method from working.

You can create a helper method for the exception.

public static void check(boolean test, String message) {
    if(!test) throw new IllegalArgumentException(message);
}

check(start < end, "Start must be before end.");