This article guides you with Oracle JRE and JDK installation on Ubuntu 18.04 operating system.

Check if Java is already on the system

 $  java -v

Update Repositories

Update the repositories using the command below.

 $ sudo apt update

Install Oracle JRE (Java Run-time Environment)

Run the following command to install the default version of JRE.

 $ sudo apt install -y default-jre

Verify JRE installation

Verify the version of JRE installed using the following command.

 $ java -version

Install Oracle JDK

Run the following command to install the default version of JDK..

 $ sudo apt install default-jdk

Verify JDK installation

Verify the version of JRE installed using the following command. Please note that “javac” is the java compiler, and it is not part of the JRE package. The javac comes with the JDK package.

 $ javac -version