Hi, I see that you are encountering some problems with your Java using your Mozilla Firefox browser.
There are 3 probable reasons why you encounter such problems with Java.
The version of your Java Plugin has been disabled, Mozilla Firefox doesn't support Java or you haven't installed Java yet.
To fix your problem we need to try some sort of solutions.
And to double check, press Ctrl+Shift+a to open Add-ons Manager and click Plug ins and check whether the Java Plug ins are enabled. (To see how it must look like refer to the picture below)
If you don't see any Java Plug ins you must download and install Java
If problem still exist download the latest Firefox (CLICK TO DOWNLOAD) and reinstall Java.
I hope this solution will fix your problem.