Java must be installed on the system first. This procedure only works with the version you download from Oracle; it will not work with the OpenJDK version of Java you’ll have when using the ‘yum install java’ command.

Download Linux x64 RPM from Oracle’s Java Downloads for All Operating Systems page.

Close Firefox.

Change to root user and enter password.

su

Change directory to /usr/java. If it isn’t created, create it.

mkdir /usr/java
cd /usr/java

Execute rpm on the Java RPM you just downloaded…

rpm -ivh /home/basejump/Downloads/jre-7u21-linux-x64.rpm

Validate with:

java -version

Delete the original RPM; you don’t need that anymore.

rm -rf /home/basejump/Downloads/jre-8u60-linux-x64.rpm

From the /usr/java directory, Find the Firefox plugin (which gets installed with java):

find . | grep libnpjp

For me, that returned:

/usr/java/jre1.8.0_60/lib/amd64/libnpjp2.so

Change to directory for Firefox plugins:

cd /usr/lib64/mozilla/plugins

Be careful. There is also a /usr/lib/mozilla/plugins directory. Be sure you’re in lib64!

Create symbolic link to the plugin:

ln -fs /usr/java/jre1.8.0_60/lib/amd64/libnpjp2.so libnpjp2.so

Start Firefox and validate by going to Tools > Addons > Plugins. You should now see Java Plug-in 1.x.x enabled.