Question

Let’s say I have a simple class called WebsterDictionary that has a function that can take a word and return its definition. Perhaps there is another function that can take a definition and return a word. The class is used all the time by many clients.

To facilitate the lookups, the class contains a member variable that is an in-memory Dictionary which stores the words and their associated definitions. Assume the Dictionary can never change once it is initialized — it’s constant and would not vary across instances.

Is this a good candidate for static class? I’ve been reading that static classes should be stateless…but this class has state (the in-memory dictionary) right?

EDIT: Also, if this does become a static class, when do I initialize the Dictionary since there would no longer be a constructor? Do I do check to see if the reference to the Dictionary is null every time one of the static methods is called?

Thanks.

Answer 1

A static class is suitable when the functionality doesn’t need to be replaceable (e.g. for tests). If you might want to use a stub or a mock, you should create an appropriate interface, and then implement it with a singleton.