Final Classes Cannot Be Superclasses
A final class cannot extended to create a subclass. All methods in a final class are implicitly final. Class String is an example of a final class. If you were allowed to create a subclass of String, objects of that subclass could be used wherever Strings are expected. Since class String cannot be extended, programs that use Strings can rely on the functionality of String objects as specified in the Java API. Making the class final also prevents programmers from creating subclasses that might bypass security restrictions.
We’ve now discussed declaring variables, methods and classes final, and we’ve emphasized that if something can be final it should be final. Compilers can perform various optimizations when ...
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