Re: what's the point in finally?

Patricia Shanahan <>
Tue, 07 Aug 2007 08:15:05 -0700
Crouchez wrote:

"Patricia Shanahan" <> wrote in message

Crouchez wrote:

Scenario A

catch(Exception e){
   //do something

why not just...

Scenario B

}catch(Exception e){
  //do something

OK right. I'm not following the arguments here. The //do something will
always be called in both scenarios unless something isn't returned in the
catch method? I don't understand why there is more use of resources
either in Scenario B? So what's the use of finally?

In the second scenario //do something will not be called if, for
example, there was a stack overflow, because StackOverflowError does not
extend Exception.

are you sure? whether code throws an exception/error/throwable or not it
will still get to //do something in both scenarios. With StackOverflowError
or OutofMemoryError then the program often stops completely.

I am sure. This program:

public class StackOverflowTest {
   public static void main(String[] args) {
     try {
       try {
       } catch (Exception e) {
         System.out.println("Exception caught");
       } finally {
         System.out.println("In finally block");
       System.out.println("After try-catch-finally");
     } catch (StackOverflowError e) {
       System.out.println("Caught " + e);
   static void badRecursion() {


In finally block
Caught java.lang.StackOverflowError

It does not reach the "After try-catch-finally" printout.

In many cases a program could in theory continue after an Error, but it
is usually not a good idea. Error implies that something is VERY wrong.

Also consider the case in which //blah contains a return statement. Code
immediately after the try-catch-finally will not get executed. The
finally block will.

Ahh i see this point. I thought return was the ultimate last in the chain -
finally does indeed get called before return but i can't think of any reason
to do that.

finally allows you to write return statements where they logically
belong and yet be sure the method's clean-up code runs.

When I saw try-catch-finally, I knew I would not miss "goto". The few
goto's I wrote in C were all emulating a finally structure, making sure
that no matter how I completed a function I would do the cleanup.


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