# Known Issues with Java Apps Running on Mac OS



## Dogwood (Nov 11, 2012)

Is there a resource where I can read about why a .jar file would run fine on a Windows comp but not work on a Mac? This is a program that the user downloads from a website and runs, it's not run through the browser. I've read that in theory Java apps are supposed to be platform-independent, but in reality they are not, unless they are written by someone mindful of the differences. Apparently filepaths are an issue, and according to another site, simply capitalizing certain words causes a problem. Trying to find some sort of Troubleshooting Guide or comprehensive list of known issues/differences.


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## sgould (Nov 11, 2012)

Have you got the latest Apple system upgrade?  If so it may have come with Java turned off.  Go to Preferences and check.  Tick the Java box if you need to.


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## Dogwood (Nov 11, 2012)

Thanks for the reply. Java is definitely turned on - the program actually runs, it just doesn't run correctly. It's supposed to print out a file that has both graphics and text. It's prints out the text but not the graphics. Text is just a header and a footer, including a time stamp, so it's created on the fly. The other issue with the text is that the upper and lower margins are not the same. There is a vertical shift upward by 1 inch, whereas on the PC they come out centered, each the same distance from the edge of the page.


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## sgould (Nov 12, 2012)

I'm not an expert and so my reply might be complete rubbish, but I thought a .jar file was compressed in some way.  If so, is the problem with the uncompressing rather than the displaying?

Some while ago I came across this and noted it in case turning off Java (when the security was questioned) caused me some problems.  But I've never used it.  It's an expander.   
http://wakaba.c3.cx/s/apps/unarchiver.html


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## Dogwood (Nov 12, 2012)

I gave the Unarchiver a try (even though the .jar extension was not explicitly listed as one of the supported file types) and I even set it as the default for all files like that. But when I went to double-click and run it, it didn't "run," it just created a new blue folder on my desktop with all the program files inside, none of which ran the program when double-clicked.

Regarding compression, in Java Preferences under "Network" there is a section called "Keep temporary files for faster access." You either check that box or you don't, when it's checked it brings to life a menu called "Select the compression levels for JAR files" with the options being None, Low, Medium, and High. So the only compression option I see is for cache files. Given that my WD is constantly tweaking and updating the program I left that box unchecked.


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