How can I be sure an earlier .jar file is not being cached by the browser?

To clear the plugin cache:

1. Open the Java Control Panel. In Windows, right mouse click on the Java icon in the System Tray (by the clock) and select 'Open Control Panel'. Or, click the 'Start' button and select 'Control Panel' (or 'Settings' and 'Control Panel') and look for the Java icon. If you do not find it, click on 'Other Control Panel Options' (on the left side) or 'Classic View' and click once on the Java icon. The Java Control Panel will appear.


2. Under the 'General' tab (or 'Cache' tab), click on the 'Settings' button (or 'Clear' button) and click on the 'Delete Files...' button.