Does a finally block always get executed in Java?
Yes, finally
will be called after the execution of the try
or catch
code blocks.
The only times finally
won't be called are:
- If you invoke
System.exit()
- If you invoke
Runtime.getRuntime().halt(exitStatus)
- If the JVM crashes first
- If the JVM reaches an infinite loop (or some other non-interruptable, non-terminating statement) in the
try
orcatch
block - If the OS forcibly terminates the JVM process; e.g.,
kill -9 <pid>
on UNIX - If the host system dies; e.g., power failure, hardware error, OS panic, et cetera
- If the
finally
block is going to be executed by a daemon thread and all other non-daemon threads exit beforefinally
is called
Example code:
public static void main(String[] args) { System.out.println(Test.test());}public static int test() { try { return 0; } finally { System.out.println("finally trumps return."); }}
Output:
finally trumps return. 0
Also, although it's bad practice, if there is a return statement within the finally block, it will trump any other return from the regular block. That is, the following block would return false:
try { return true; } finally { return false; }
Same thing with throwing exceptions from the finally block.