I’ll show you how to install the Java runtime plug-in for Mozzilla Firefox in Ubuntu’s terminal command line program by downloading the self-extracting .bin installer from Java.com and running it in Terminal and verifying it on Java.com.
Java is a runtime program which lets you run applications like games, office suites, media players, etc coded in Java on your web browser or computer. It is one of the most popular open source programming languages in the world.
Once you downloaded the JavaInstaller.bin file to your default download folder in Ubuntu. You need to be login as an administrator root user.
Open up Terminal in Applications menu>Accessories>Terminal
In terminal, type these commands
chmod a+x NameOfJavainstaller.bin
./NameOfJavainstaller.bin (press enter)
Go back to Java.com to verify your install, and let Mozilla firefox install the needed plug-ins for it.
Congrats now you installed Java.