Re: Determining the Main Class

Daniel Pitts <>
Tue, 12 Aug 2008 21:17:49 -0700
Arne Vajh?j wrote:

Daniele Futtorovic wrote:

On 11/08/2008 19:54, Stefan Ram allegedly wrote:

Jason Cavett <> 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.main(]

  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.

Do you get same problem with:
  ManagementFactory.getThreadMXBean().dumpAllThreads(false, false)

I haven't tested, but I would assume that this might exemplify the problem:

public class HiddenMain {
    public static void main(String...arg) {
        new Thread() {
           public void run() {
        // Main thread ends.

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

And some apps may have none.

My favorite example:
enum E{A;{System.exit(1);}}
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