Re: Determining the Main Class

On 11/08/2008 19:54, Stefan Ram allegedly wrote:
Jason Cavett <jason.cavett@xxxxxxxxx> writes:
Is there a way to determine (maybe through reflection or something?)
where a Java application is being run from (what class contains the
main method)?

Examine the stack trace.

public class Main { public static void method() { System.out.println
( java.util.Arrays.toString
( java.lang.Thread.currentThread().getStackTrace() )); }
public static void main( final java.lang.String[] args ) { Main.method(); }}

[java.lang.Thread.getStackTrace(Unknown Source), Main.method(Main.java:24), Main.main(Main.java:28)]

In the stack trace above, it is the last entry. This might
not always be so. Also, there might be other methods with
the signatur of main in the stack trace. So, some care has
to be taken. Often, it should be the last method in the
stack trace with the signature of main.

The code above also assumes that the current thread is
the main thread.

I've investigated that a bit, trying to get the main Thread through
searching the ThreadGroups, and also via Thread.getAllStacktraces.

There's a problem with that approach. To wit, that if the main Thread
isn't *active*, you don't get it either way (at least that's what my
tests indicate).

I would venture say that in a typical application, the main Thread isn't
active. So this approach might not work.

As for searching for defined classes with a main method, that's
pointless, since many classes can have a main defined.

As Mark said, it would work with a JAR (via its manifest). Ideally,
you'd have to know the command the java executable was started with to
deal with all cases...

--
DF.
.

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