When JNLP files are run using Mac OS X, there are two possible Web Start programs that may be used, one for Java 1.4 and one for 1.5. This can be confusing, as the cache directories are in two different locations, and clearing only one of them may not fix whatever problem you are trying to fix.

The two locations are as follows:

Java 1.4 Web Start

username/Library/Caches/Java Web Start/cache

To clear this cache, go to

Applications/Utilities/Java/Java Web Start.app

then click "Preferences" from the program's menu, and then click "Clear Folder" under "Applications Folder Options."

Java 1.5 Web Start

username/Library/Caches/Java/cache/javaws

To clear this cache, go to

Applications/Utilities/Java/J2SE 5.0/Java Cache Viewer.app

Then select all the relevant applications and click "Remove" at the bottomn. While this appears to make Web Start re-download all relevant JARs, it doesn't actually clear the directory. If you need to do this, select "Preferences" from the program's menu, then click "Delete Files..." under "Temporary Internet Files."