Code not reaching "finally" block

Question

The given java code is not going to the finally block, I thought these blocks were supposed to execute no matter what:

public static void main(String[] args) {
    try {
        System.out.println("Hello world");
        System.exit(0);
    } finally {
        System.out.println("Goodbye world");
    }
}

There is no `catch` block and no exception. What do you expect? — Fabian Schmengler, Jan 29 '13 at 08:14
+1 Interesting question, the wording just makes it hard to figure out what you want to know. — Aaron Digulla, Jan 29 '13 at 08:15
I've changed the title to remove the *exception* and replaced by *finally*. And even with a `catch` block, the question remains the same... — Romain Linsolas, Jan 29 '13 at 08:15
@romaintaz, looks like we crossed edits but, since my code reformatting also included your finally change, I'll leave as is. — paxdiablo, Jan 29 '13 at 08:26

score 5 · Answer 1 · answered Jan 29 '13 at 08:13

5

System.exit(0);

will unload the JVM i.e no further java instructions are processed That is the reason for not being exicuting the finally{}

answered Jan 29 '13 at 08:13

TheWhiteRabbit

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score 4 · Answer 2 · answered Jan 29 '13 at 08:13

4

Yes, that's normal. The finally blocks is always executed, except in the case where the JVM is stopped before reaching the end of the code, which is your case here, as you exit the JVM.

answered Jan 29 '13 at 08:13

Romain Linsolas

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score 4 · Accepted Answer · edited Jun 20 '20 at 09:12

As stated in the Java 6 System.exit() docs:

The call System.exit(n) is effectively equivalent to the call: Runtime.getRuntime().exit(n)

And, if you go and look at Runtime.exit() (my bold):

Terminates the currently running Java virtual machine by initiating its shutdown sequence. This method never returns normally.

The virtual machine's shutdown sequence consists of two phases. In the first phase all registered shutdown hooks, if any, are started in some unspecified order and allowed to run concurrently until they finish. In the second phase all uninvoked finalizers are run if finalization-on-exit has been enabled. Once this is done the virtual machine halts.

Basically, the only one this function can return (and hence allow the finally clause to run) is for it to raise a SecurityException because whatever security manager is running disallows exiting with the given code.

Thanks that was really descriptive and helpful. – newUser Jan 29 '13 at 08:30 — newUser, Jan 29 '13 at 08:30

score 2 · Answer 4 · edited May 23 '17 at 10:24

2

The System.exit method stops the execution of the current thread and all others threads. The presence of a finally does not give a thread special permission to continue executing.

A previous discusses this in great detail. How does Java's System.exit() work with try/catch/finally blocks?

edited May 23 '17 at 10:24

Community

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answered Jan 29 '13 at 08:14

AurA

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score 0 · Answer 5 · answered Jan 29 '13 at 08:22

0

By System.exit(0) You are exiting from Jvm so no lines after this will get executed and That's why you are finding your finally block as unexecuted.

answered Jan 29 '13 at 08:22

Abhishek_Mishra

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Code not reaching "finally" block

5 Answers5