Call return statement or System.exit on try or catch block

Question

I got the following question asked in interview :

What will happen if one calls a return statement or System.exit on try or catch block ? Will finally block execute?

Does the finally block always get executed?

EDIT: After trying the above in java:

1. finally block executes if I put return statement in try block or catch block but

2. finally block doesn't run if I call System.exit form try or catch.

I don't get the reason behind though.

Answer 1

What will happen if one calls a return statement or System.exit on try or catch block ?

Will finally block execute?

In the case of a return, Yes. If you want the gory details, they are specified in JLS section 14.20.2.

(Note that in the JLS terminology, a return counts as an abrupt termination. But that doesn't matter, because when you analyse the spec carefully, you will see that the finally gets executed for both normal and abrupt terminations.)

In the case of a System.exit(), No. The call to the exit method never returns, and it doesn't throw an exception either. Therefore the "enclosing" finally clauses for the thread never get executed.

(In JLS parlance, the exit() call doesn't "terminate" at all. It conceptually the same as a method going into an infinite loop that (magically) doesn't use any CPU time. All of the activity associated with JVM shutdown happens on other threads.)