Java-

Java and JVM both are required for running multiple software like Tomcat, Jetty, Glassfish and many more.

In this post i will install JRE and JDK using apt. You should know our Ubuntu 20.04 comes with Open JDK 11, which is an open-source variant of the JRE and JDK.

Install the JRE/JDK

please update the package index first

$ sudo apt update

$ sudo apt install default-jre

this open JRE will allow you to run almost all Java software.

$ java -version

You can check and verify this.

Now you think what about the JDK to compile and run java base software, To install JDK run the below command.

$ sudo apt install default-jdk

Set the JAVA_HOME Environment Variable

For setting up java_home environment , check the location where your java is installed. use below command to get.

$ sudo update-alternatives --config java

Output like below if you follow above steps

There are 1 choices for the alternative java (providing /usr/bin/java).

  Selection    Path                                         Priority   Status
------------------------------------------------------------
  0            /usr/lib/jvm/java-11-openjdk-amd64/bin/java   1111      auto mode

Now run

$ sudo nano /etc/environment

at the end of file append the below code,

JAVA_HOME="/usr/lib/jvm/java-11-openjdk-amd64"

Note- this is your java path might be in your system this is different “/usr/lib/jvm/java-11-openjdk-amd64”. Copy this path carefully.

Save the file and exit the editor.

For applying the change in current session use below command

$ source /etc/environment

and now all done, check you java version

$ echo $JAVA_HOME

Output 

/usr/lib/jvm/java-11-openjdk-amd64

All Done.

Thanks , Happy coding.