If they do, when do they use it so I can understand it better and know when to use it.
A final
class is simply a class that can’t be extended.
(It does not mean that all references to objects of the class would act as if they were declared as final
.)
When it’s useful to declare a class as final is covered in the answers of this question:
If Java is object oriented, and you declare a class
final
, doesn’t it stop the idea of class having the characteristics of objects?
In some sense yes.
By marking a class as final you disable a powerful and flexible feature of the language for that part of the code. Some classes however, should not (and in certain cases can not) be designed to take subclassing into account in a good way. In these cases it makes sense to mark the class as final, even though it limits OOP. (Remember however that a final class can still extend another non-final class.)