Installing the JDK

First, we need to make sure that we have an up-to-date installation of the Java Runtime Environment (JRE). The recommended Java version for Cassandra 3.0 is Oracle Java 1.8. Make sure you have the correct Java Development Kit (JDK) version installed. Go to http://www.oracle.com/technetwork/java/javase/downloads/index.html, and download and install the appropriate JDK. Open the Terminal application, and type the following into the command prompt:

    $ java -version

You will see an output that looks similar to the following:

    java version "1.8.0_65"
    Java(TM) SE Runtime Environment (build 1.8.0_65-b17)
    Java HotSpot(TM) 64-Bit Server VM (build 25.65-b01, mixed mode)    

Once you've got the right version of Java, you're ready to install Cassandra.