Question

After reading some questions and answers about enum I don’t find it really useful…

It’s something between class and a variable but I know where can I use it so it would be more useful then a class, or a couple of variables for example.

Answer 1

There are other things you can do and reasons to use them, but the primary reason I use enums is to prevent the possibility of an invalid parameter. For example, imagine the following method:

public void doSomethingWithAMonth(int monthNum);

This is not only ambiguous (do month indexes start at 1, or at 0?), but you can give down-right invalid data (13+, negative numbers). If you have an enum Month with JAN, FEB, etc. the signature becomes:

public void doSomethignWithAMonth(Month month);

Code calling this method will be far more readable, and can’t provide invalid data.