[Tutor] Java Virtual Machine Launcher Question

Steven D'Aprano steve at pearwood.info
Mon Dec 27 05:14:39 CET 2010

Apologies if you get (half of) this message twice, I'm having trouble 
with Thunderbird.

Ben Ganzfried wrote:
> Happy holidays everyone!
> My current question relates to a broader python programming question I
> have and so I thought it was worth posting here.  I'm trying to read a
> single MAGE-TAB file (http://www.mged.org/mage-tab/) and acquire
> metadata.

This doesn't sound like it has anything to do with Python at all.

> I just downloaded WinRAR to open zip files, but when trying to open
> the .jar file for my converter, I get the following message:

What is your converter?

How are you trying to open the file? Double-clicking (that's my bet), 
choosing Open from the WinRAR menu, right-click in Windows Explorer, or 
something else?

> "Java Virtual Machine Launcher:
> Failed to load Main-Class manifest attribute from
> C:\Users\Ben\AppData\Local\Temp\Rar$DI01.718\isatools_deps.jar"

This sounds like Windows is trying to run the Java file rather than open 
it in WinRAR. If you google on the error message:

"failed to load main-class manifest attribute from"

you'll find lots of questions that basically say "Whenever I try to run 
my .jar file...". So I'm pretty sure that you may have *installed* 
WinRAR, but you're not *using* WinRAR.

> If anyone could help me better understand how to fix this, what is
> happening and/or point me in the right direction, I would be very much
> obliged.

Lesson one: Google on the error message.

Lesson two: you need to be more specific in what you're doing. It's not 
enough to say "I'm trying to open the file..." -- you may be *trying*, 
but are you sure you're succeeding? Is there any sign that WinRAR is 
actually involved?

Good luck!


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