Re: try catch finally misbehaving

From:

Lew <noone@lewscanon.com>

Newsgroups:

comp.lang.java.help

Date:

Wed, 26 Aug 2009 09:07:22 -0400

Message-ID:

<h73c2c$3e6$1@news.albasani.net>

Mark Smith wrote:

(Or more likely my understanding is flawed)

In the below code I have a test function, that returns a string and
always triggers a null pointer exception.

The test function handles internally sqlexceptions and finally returns
a result.

I want the calling function to handle general exceptions (in this
example the null pointer exception).

However in this example the general exception handler is never
triggered (the function still returns "FAILED" as expected).

Why is this happening?

Because you return from the 'finally' instead of the 'try'. If you read the
Java Language Specification (JLS) carefully, you will see that an early
termination or return from 'finally' replaces any early termination or return
from the 'try' or 'catch' blocks. Normally you don't return or throw from a
'finally' block.

Example code:
..
    // Should always fail and trigger null pointer exception
    public static String testFunc()
    {
        String outcome="FAILED";
        Object nullRef=null;
        try
        {
           nullRef.toString();
           if(false)
           {
               throw new SQLException();
           }
           outcome="SUCCESS";
        }
        catch (SQLException e)
        {
            outcome="SQLException";
        }
        finally
        {
            return outcome;
        }
    }

Lew