Java and JVM (Java Virtual Machine) are required for many types of popular software, including Tomcat, Jetty, Glassfish, Cassandra and Jenkins.

check if Java is already installed:

java -version

First, update the package lists:

sudo apt update

Install OpenJRE:

sudo apt install default-jre

Type y (yes) and press Enter to resume installation.

Confirm Java version:

java -version

You may need the Java Development Kit (JDK) in addition to the JRE in order to compile and run some specific Java-based software. To install the JDK, execute the following command, which will also install the JRE:

sudo apt install default-jdk

Verify that the JDK is installed by checking the version of javac, the Java compiler:

javac -version