Re: Exception Jargon

From:

Patricia Shanahan <pats@acm.org>

Newsgroups:

comp.lang.java.programmer

Date:

Mon, 09 Jul 2007 11:24:30 -0700

Message-ID:

<f6tuh0$dot$1@ihnp4.ucsd.edu>

getsanjay.sharma@gmail.com wrote:
....

Thanks for the wonderful explanation Patricia. I do understand that
its based on the JLS on how the language behavior is handled by the
JVM, but I was looking for an explanation in low level terms (stack
frames etc.) or the way the OS handles exceptions. I know maybe I am
asking too much or being foolish here, but I think I need some good
tutorials on how things work under the hood rather than
specifications.

I don't think there is one lower level implementation that is
necessarily used in the JVM. If you want to know how a particular JVM
does it, you need source code access to that JVM.

You can go down one level by studying the Java Virtual Machine
Specification, http://java.sun.com/docs/books/jvms/

One question though..

public class Bitwise
{
    public static void so()
    {
        try
        {
            double a = 123;
            double b = 123;
            if(a == 123.0)
                System.out.println("Same");

            System.out.println(1/0);
        }
        catch(Exception e)
        {
                System.out.println("In catch");
                throw new NullPointerException();

        }
        finally
        {
            System.out.println("This is finally");
            return;
        }

    }
    public static void main(String[] args)
    {
        so();
    }
}

In the above snippet, no exception is raised. Is this because the
return statement in the finally block makes all the exceptions in the
current scope of the method disappear? Or does it mean that the
exception is ignored when the finally block contains the return
statement.

The return causes the finally block to complete abruptly, so the
try-catch-finally completes abruptly for the same reason. I know you say
you don't need specifications, but the spec section I pointed out would
have told you exactly what to expect.

Patricia