Question

I wont try to extends a Pattern because we can’t (I will wrap), but I would like to know why Pattern class is final ?

I mean this class could be extended for a largest use but they did the choice to make it final. Why ?

If i ask it, it is more in a technical (curious ?) way than in a “java is so bad” way.

Answer 1

It’s final specifically to prevent you from extending it, because it is not designed to be subclassed. Pattern instances are immutable and thread-safe, neither of which would be guaranteed if you created your own subclass of Pattern.

• Why is the java.util.Scanner class declared 'final'?
• Why is String class declared final in Java?

• And of course, the all-important Effective Java quote:

  Item 17: Design and document for inheritance or else prohibit it