If Java is not working, make sure that the Java plugin is enabled in the Add-ons Manager: Click the menu button and choose Add-ons Add-ons. The Add-ons Manager tab will open. In the Add-ons Manager tab, select the Plugins panel. Click on the Java(TM) Platform plugin Java Applet Plug-in Java plugin to select it. read more
1. Use 32 bit Java as firefox only supports 32 bit java (Even your machine is 64 bit) 2. Download 32 bit java exe i.e jdk-7u80-windows-i586.exe and install it on your machine. 3. Go to jre7/bin folder and find javacpl i.e. java control panel application. Start it and enable java in both security and java tabs. read more
After acknowledging the Firefox alert, you should see a listing of the configuration preferences. Right-click anywhere inside the displayed list of preferences. Select New then select Boolean. Add property name as dom.ipc.plugins.java.enabled Add Preference name as dom.ipc.plugins.java.enabled. A window will be displayed, select false. Then select OK. read more