In this guide, we will describe how to install Java on Ubuntu 20.04.

Installing OpenJDK 11

Open Terminal, As always first check for updates

sudoapt-get update

Then type following command in terminal

sudoaptinstallopenjdk-11-jdk

when asked for [ Y/n ], Type Y

Once the installation is complete, you can verify it by checking the Java version:

java-version

The output should look something like this:

openjdk version"11.0.7" 2020-04-14OpenJDK Runtime Environment(build 11.0.7+10-post-Ubuntu-3ubuntu1)OpenJDK 64-Bit Server VM(build 11.0.7+10-post-Ubuntu-3ubuntu1, mixed mode, sharing)

JAVA_HOME Environment Variable

TheJAVA_HOMEenvironment variable is used by some Java applications to determine the Java installation location.

To set theJAVA_HOME variable, first find the Java installation path withupdate-alternatives:

sudo update-alternatives --config java

In this example, the installation paths are as follows:

• OpenJDK 11 is located at/usr/lib/jvm/java-11-openjdk-amd64/bin/java

Once you found the path of your preferred Java installation, open the/etc/environment file:

sudo nano /etc/environment

Assuming you want to setJAVA_HOME to point to OpenJDK 11, add the following line, at the end of the file:

/etc/environment

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

For changes to take effect on your current shell you can either log out and log in or run the following[source](https://linuxize.com/post/bash-source-command/) command:

source /etc/environment

Verify that theJAVA_HOME environment variable was correctly set:

echo $JAVA_HOME

You should see the path to the Java installation:

That’s it! At this point, you have successfully installed Java on your Ubuntu system!

Now for complete assurance

Open any text editor type following following code

classSimple{publicstaticvoidmain(Stringargs[]){System.out.println("Hello Java");}}

save this code as Simple.java

cd to the folder where the program is saved.

then compile using following command in terminal. ( remember S is capital in Simple )

javacSimple.java

and then run using following command

javaSimple

If you are able to see this output ..... then your java is successfully installed on Ubuntu!

Hello Java

Uninstalling Java

You can uninstall Java like any other package installed with apt .

For example, to uninstall the default-jdk package enter:

sudoapt remove openjdk-11-jdk

Conclusion

OpenJDK 11 and OpenJDK 8 are available in the default Ubuntu 20.04 repositories and can be installed using the apt package manager.

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