JRE Error: "Java Virtual Machine Launcher Could Not Find the Main Class."

[aquacentaur]

Question: I am experiencing very odd issues with the Java Runtime Environment. (Win XP Install) Whenever I try and open a JAR file (IE: Limewire) it will not complete loading with no error message. When I try and access the Java control panel I receive the error that "Java Virtual Machine Launcher Could Not Find the Main Class. Program Will Exit." I have tried everything that I know to do (see list below) and Sun's website says that this may have somehting to do with a registry reference; however, they provide no fixes.

Listing of what I have tried thus far:

-Uninstalled all versions of JRE, deleted all folders and files related to Java, and removed all registry keys related to all java installations.
-Reinstalled Java using the offline installation.
-Tried installing in a different folder and at the root system level C:/
-Tried creating a new user account and installing there.
-Ran antivirus, spyware, registry, system update, etc.
-Tried installing an older version of Java (Past three releases)
-No conflicting system processes. I only have 19 running in the background.
-Tried installing from the web.
-Tried using the installer with Limewire.
-Some websites reference that when programming for Java this would be caused by an incorrect system reference to the Java classpath. However, they provide no solutions.

I am out of ideas on how to correct this problem because my knowledge of the JRE system is not advanced enough to know what the next step would be. Any assistance would be greately appreciated.

I look forward to everyone's thoughts on this issue.

Here are some additional respones from my Experts-Exchange thread and none of this suggestions have fixed the issue either.

Check My Computer --> Properties --> Advanced --> Environment Variables that CLASSPATH is set correctly for JRE and reboot.


08.15.2008 at 10:19PM EST, ID: 22242939




Check environment variables and it did reference the folder of an older installation. I changed the folder; however, I am still experiencing the problem. Here is what the CLASSPATH state says
C:\Program Files\Java\jre1.6.0_07\lib\ext\QTJava.zip;C:\Progr am Files\Java\jre1.6.0_07\lib\ext\QTJava.zip;C:\Progr am Files\Java\jre1.6.0_07\lib\ext\QTJava.zip
I have a feeling that the libraries have been updated in the most recent version; however, I do not know the correct CLASSPATH statement to place here. Do you know what it is for the most current version?









08.15.2008 at 10:25PM EST, ID: 22242949



I'd suggest clearing your classpath altogether, but its not the cause of your problem.
do a search for jre in the registry and see what settings are in there.










08.15.2008 at 10:41PM EST, ID: 22242982




Should only be on in the CLASSPATH.
Here is mine:

.;C:\Program Files\Java\jre1.6.0_02\lib\ext\QTJava.zip











08.15.2008 at 10:42PM EST, ID: 22242985




humanonomics:
From what I see, the problem is not with JVM, JVM is fine, it says it cannot find "the main class", it means the Jar you are trying to execute, either does not have a main class or the main class is not mentioned in the manifest file. Get a proper jar, get the info on how the author of that jar wants you to execute it.








08.15.2008 at 10:42PM EST, ID: 22242987




mwvisa1:
I haven't loaded update 7 yet, so just replace _02 with _07 and should be your correct setting.








08.15.2008 at 10:45PM EST, ID: 22242992




mwvisa1:
Do java -version at command prompt and if you get proper reply you can rule out the CLASSPATH theory you found on cause of issue and see if just this JAR having problems. They may need this JAR added to class path or executed from a specific path or with specific command arguments.








08.15.2008 at 11:28PM EST, ID: 22243085




RogerConner:
Updates to everyone's suggestions:
This problem is occuring system wide (all JARs and JAR loaded via websites). This error occures when I try and open the Java Control panel. All other Java applications simply will not load at all and do not produce an error message.
I tried the Java -Version and it is reporting the correct version that is installed on the machine.
Also, in regards to the classpath I tried changing it to just one and it did not solve the problem and I also tried removing the CLASSPATH entirely.
I tried searching the registery for JRE and no keys or values are reported. However, I may not be searching correctly. I did remove all old registry keys for Java when I did the complete re-install.
One interesting thing is that the classpath references a file that does not exist on my system. In the ext folder there is no QTJava.zip file which is quite odd.
Other suggestions?









08.16.2008 at 12:01AM EST, ID: 22243167




humanonomics:
What java version are you using ?











08.16.2008 at 12:07AM EST, ID: 22243180




RogerConner:
I am using Update 7 and I have tried installing the previous three releases with no luch.








08.16.2008 at 12:35AM EST, ID: 22243216




humanonomics:
hmm, I have update 6 and 7 and in ext folder I have QTJava.exe in update 6 but not in 7. and I am not facing any problems with jars.








08.16.2008 at 01:39AM EST, ID: 22243347




RogerConner:
On further research QTJava.zip is QuickTime Java (Installed with Quicktime and iTunes) it would not have any impact on this issue.
Everything I look at refers to the main class not being set.












08.16.2008 at 08:39AM EST, ID: 22244059




humanonomics:
this only means one thing to me, the manifest file of the jar does not have the main class reference.

Can you point out any of the address these jars are taken from, I can try this out at my end.

Thanks










08.16.2008 at 04:11PM EST, ID: 22245229




RogerConner:
One of the JARs is the common control panel launcher in Win XP that launches the JRE JAR Control Panel. The other one I have tried is Limewire (www.limewire.com). Also, general websites that call the <applet> object do not function either.








08.16.2008 at 05:57PM EST, ID: 22245468




RogerConner:
I have checked all of the registry keys and they reference the correct folder on the system. I also tried an install at the root level and changed the classpath and it still did not fix the issue.
I also tried echo %CLASSPATH% and it is reporting the correct directory. I have also tried added additional Java directories to the CLASSPATH statement.
Any other suggestions? My searches on the web show that a lot of people are having this problem; however, none actually provide a solution.
I look forward to further suggestions.

------

That is the history of where we are at with this issue. Limewire begins to start-up and then nothing happens. When I open the Java Control Panel I receive an error. I have also tried to open Limewire using the Command Prompt and I receive the same error about the "Main Class"

Any suggestions would be helpful as you can see we have tried many different potential solutions.

[Remoc]

I would just start from scratch. Start > All Programs > LW > Uninstall.

Now once uninstalled, go back to Start > Search > type in limewire and search All Files and Folders.

Now if search finds anything LW related Delete Everything that It finds. Now Download Crap Cleaner which will clean your Registry and also clean a ton of Junk from your system.

Now Remove All Java versions installed (via Add/Remove Programs) before you install the latest Version. (Download the JRE Offline Installer)
Java SE Downloads Fifth one down. Run Ccleaner again Before the new Java Install.

Once you have installed the Latest Version of Java, Now you can Download Limewire fresh and clean.

ONLY Download LW from Here. Lime Wire » Official Website & Free Download, BitTorrent «
Hope This Helps.