Are there any general guidelines as to when to make a class final?
I thought it was if you did not want people extending your class, but that seems slightly…. naive??
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Are there any general guidelines as to when to make a class final?
I thought it was if you did not want people extending your class, but that seems slightly…. naive??
Making a class final only prevents it from being extended as you note. Why would you want to do that?
One typical use case is to guarantee immutability. If you design an immutable class but don’t make it final, it can be extended in a mutable way. This can in turn lead to a subclass corrupting a class invariant or creating concurrency issues.
You could also simply mark a class as final to document the fact that it is not designed to be extended. See for example Effective Java #17: “Design and document for inheritance or else prohibit it”.