I always manage to over look installing Oracle Java, until I visit a site that needs to load java and it fails. Thankfully Linux Mint makes this simple. Open up the trusty Terminal.
1. Add the Java repo.
sudo add-apt-repository ppa:webupd8team/java
2. Update the source list
sudo apt-get update
3. Install it
sudo apt-get install oracle-java8-installer
This will take a bit depending on your internet connection you will also have to accept the license from Oracle.
John Learns Linux...again 