Question

I am trying to create a Response class in Java which has a method

void setResponse(String response);

Different response subclasses will have different requirements for the response. The string that is passed to the function is received from the user.

What is the correct way of handling a wrong response?

1. Should the function throw an exception like IllegalResponseException
2. Should the function be declared like
   

   boolean setResponse(String response, String errorMsg)

and return false if the response is wrong and set the error message to the appropriate value

Edit:
I want to design the UI so that I keep prompting the user for a response until a correct one is entered.

Answer 1

This depends somewhat on what you want the program to do when incorrect response is set.

If it’s a 100% critical thing and the program should never proceed in such a case, throw an exception.

If it needs to be handled correctly by the caller and continue execution of the program, you can do either one, but I personally prefer #2. Why?

A great discussion of exceptions for error handling is here – it does not directly address exceptions vs. return codes but a very clear list of downsides of criticisms of checked exceptions applies to this discussion as well (again, this is assuming the error you’re handling is not a super-critical one which should cause program termination, in which case an unchecked exception is proper).