In chapter 4 of the Hadoop course we set up a new Virtual Machine, running Linux. This step is not needed if you're already using Linux or a Mac to run the course, but is needed for Windows users.
In the course we install the Java JDK version 7. However this is no longer available from the repositories, and you'll now need to use Java version 8. We've tested the course with this version of Java and are not aware of any issues.
To install Java version 8 issue the following command:
sudo apt-get install openjdk-8-jre-headless
sudo apt-get install openjdk-7-jre