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From: Ross on 5 Oct 2009 07:50
On Oct 5, 11:41 am, Toffstier <mjcap...(a)gmail.com> wrote:
> public static String getMainClassName()
> {
> for(final Map.Entry<String, String> entry : System.getenv().entrySet
> ())
> {
> if(entry.getKey().startsWith("JAVA_MAIN_CLASS"))
> return entry.getValue();
> }
> throw new IllegalStateException("Cannot determine main class.");
> }

Thanks, but this doesn't work for me. Even trying to create the parent
class leads to an error being thrown.

$ java TestMain
Exception in thread "main" java.lang.IllegalStateException: Cannot
determine main class.
at TestMain.getMainClassName(TestMain.java:14)
at TestMain.main(TestMain.java:19)
$

Here are the keys available on my computer.

entry key is TERM
entry key is SSH_AGENT_PID
entry key is JAVA_HOME
entry key is SHLVL
entry key is JMFHOME
entry key is XFILESEARCHPATH
entry key is GDM_XSERVER_LOCATION
entry key is SESSION_MANAGER
entry key is COLORTERM
entry key is GNOME_DESKTOP_SESSION_ID
entry key is MAIL
entry key is GDMSESSION
entry key is HOSTNAME
entry key is PWD
entry key is FIREFOX_DSP
entry key is WINDOWID
entry key is KDEDIR
entry key is LOGNAME
entry key is G_BROKEN_FILENAMES
entry key is QTDIR
entry key is _
entry key is SSH_AUTH_SOCK
entry key is NLSPATH
entry key is GNOME_KEYRING_SOCKET
entry key is LD_LIBRARY_PATH
entry key is OLDPWD
entry key is SHELL
entry key is INPUTRC
entry key is DBUS_SESSION_BUS_ADDRESS
entry key is HISTSIZE
entry key is GTK_RC_FILES
entry key is CLASSPATH
entry key is PATH
entry key is JRE_HOME
entry key is DESKTOP_SESSION
entry key is DISPLAY
entry key is USER
entry key is DESKTOP_STARTUP_ID
entry key is HOME
entry key is PKG_CONFIG_PATH
entry key is LESSOPEN
entry key is XAUTHORITY
entry key is HTC_XML
entry key is LS_COLORS
entry key is LANG
entry key is SSH_ASKPASS

Here's the source code I used.


import java.util.*;

public class TestMain
{

public static String getMainClassName()
{
for(final Map.Entry<String, String> entry : System.getenv
().entrySet
())
{
System.out.println( "entry key is " + entry.getKey() );
if(entry.getKey().startsWith("JAVA_MAIN_CLASS"))
return entry.getValue();
}
throw new IllegalStateException("Cannot determine main class.");
}

public static void main( String args[] )
{
System.out.println( "main class is " + getMainClassName() );
}
}
From: Mike Schilling on 5 Oct 2009 11:45
Toffstier wrote:
> On 15 Sep., 03:32, "Mike Schilling" <mscottschill...(a)hotmail.com>
> wrote:
>> Arne Vajh�j wrote:
>>>>> If we can assume that Java version >= 1.5, main thread has
>>>>> thread id 1 and max. stack depth is 1000:
>>
>>>>> StackTraceElement[] ste =
>>>>> ManagementFactory.getThreadMXBean().getThreadInfo(1,
>>>>> 1000).getStackTrace(); String clznam =
>>>>> ste[ste.length-1].getClassName();
>>
>>>> Is that really going to give you the class mentioned in the
>>>> command
>>>> line rather than the class which defines the static main()
>>>> method?
>>
>>> You are correct. It returns the parent class where main is
>>> defined.
>>
>> Right. My strong impression is that trying to figure out which
>> subclass was mentioned in the command line is simply hopeless (or
>> at
>> best extremely non-portable) and that, accordingly, the OP should
>> figure out some other way of doing things. Fortunately, there are
>> dozens of them.
>
> public static String getMainClassName()
> {
> for(final Map.Entry<String, String> entry :
> System.getenv().entrySet ())
> {
> if(entry.getKey().startsWith("JAVA_MAIN_CLASS"))
> return entry.getValue();
> }
> throw new IllegalStateException("Cannot determine main class.");
> }

How is JAVA_MAIN_CLASS getting set? It's not something the JVM does
automagically.


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