Don't throw THAT exception

There are many reasons for throwing an exception in your code, but please take a second to think about what you are doing. En exception is something you do not want occuring. You should always try and code in a manner that does not throw exception. It called an ‘exception’ FFS.

I found this code today (rewritten as abstract):

public Answer fetchAnswer(String nr) {
        try {
            return logic.fetch(nr);
        } catch(Exception e) {
            // Removed several else if (e instanceof Type)
            if(e instanceof WaitingForFetchExternalException){
                return someService.fetchFromExternal(nr);
            }
        }
}

//An implementation of _logic_
public Ansver fetch(String nr) {
    //Removed some logic that check if external fetch should be used. 
    throw new WaitingForFetchExternalException("Is being fetched from external");
}

This code uses polymorphism on the service named logic, and, depending on environment the application is deployed in, different implementations of logic is used. One of which (!) throws the exception WaitingForFetchExternalException. The problem is of course that it is not an exception at all, it is the expected behavior of this particular implementation of logic. This is an exceptionally bad way to use exceptions and is probably introduced in the code base because it is convenient (ie. easier in untested code) to use the glorified GOTO statement an exception can be. This code should be refactored.

Some say this is pragmatism. I call it just bad code.

Here is a good read on the same topic with more examples