How to Install Java on Debian 10

Introduction

Before we begin talking about how to install Java on Debian 10, let’s briefly understand – What is Java?

Java is a widely used programming language known for its versatility and compatibility. Developed by Sun Microsystems, it allows developers to write code that can run on different platforms, including computers, mobile devices, and embedded systems.

Java is an object-oriented language, making it easier to organize and structure code. With its robust libraries and tools, Java enables developers to create a wide range of applications, from simple desktop programs to complex enterprise systems. Its popularity and active community support make Java a solid choice for developers looking to build scalable and reliable software solutions.

In this tutorial, you will install Java on Debian 10. You can follow the same guidelines for other Ubuntu-based distribution, including Kubuntu, Linux Mint, and Elementary OS. We will also address some FAQs related to the Java installation.

Advantages of Java

1. Platform Independence: Java code can run on multiple platforms without needing to be rewritten.
2. Object-Oriented Programming: Java's OOP approach allows for modular and reusable code.
3. Robust Libraries: Java offers a vast collection of pre-built libraries for various functionalities.
4. Strong Community Support: Java has a large community of developers, providing resources, assistance, and frequent updates.
5. Scalability and Reliability: Java's architecture and features make it suitable for building large-scale, robust, and stable applications.

Before You Begin

The only major distinction between OpenJDK and Oracle Java is that Oracle Java has some additional commercial features. The Oracle Java License only permits non-commercial uses of the program, such as private and development use.

The Java Runtime Environment (JRE) and Java Development Kit (JDK) are two separate Java packages included by default in the Debian 10 repositories. JRE, which comes with the Java virtual machine (JVM), classes, and binaries, allows Java programs to be run. Installing JDK, which includes JRE and the development/debugging tools and libraries required to create Java applications, is recommended for Java developers.

The general advice is to stick with the default OpenJDK (JDK 11) version if you are unsure about which Java package to install. You should review the application documentation because some Java-based applications might require a particular Java version.

Installing OpenJDK 11

The open-source Java Platform implementation OpenJDK 11 is the default Java development and runtime in Debian 10, Buster.

For the packages index to be updated and the OpenJDK 11 JDK package to be installed, run the following commands as root or a user with sudo privileges:

sudo apt update
sudo apt install default-jdk

You can check the Java version to see if the installation was successful once it is finished:

java -version

The final result should resemble this:

Output

openjdk version "11.0.3" 2019-04-16
OpenJDK Runtime Environment (build 11.0.3+7-post-Debian-5)
OpenJDK 64-Bit Server VM (build 11.0.3+7-post-Debian-5, mixed mode, sharing)

All done! You have now successfully installed Java on your Debian-based machine.

Installing OpenJDK 8

The official Debian Buster repositories do not currently have the prior Java LTS version 8 available.

We will activate the AdoptOpenJDK repository, which offers prebuilt OpenJDK packages.

1) Begin by updating the package list and installing the dependencies required to add a new repository over HTTPS:

sudo apt install apt-transport-https ca-certificates wget dirmngr gnupg software-properties-common

2) Use the wget command below to import the repository's GPG key:

wget -qO - https://adoptopenjdk.jfrog.io/adoptopenjdk/api/gpg/key/public | sudo apt-key add -

3) You should now configure the AdoptOpenJDK APT repository to your system:

sudo add-apt-repository --yes https://adoptopenjdk.jfrog.io/adoptopenjdk/deb/

4) Use the following commands to update apt sources and install Java 8 after the repository has been enabled:

sudo apt update
sudo apt install adoptopenjdk-8-hotspot

5) Finally, check the Java version to confirm the installation:

java -version

The final result should resemble this:

Output

openjdk version "1.8.0_212"
OpenJDK Runtime Environment (AdoptOpenJDK)(build 1.8.0_212-b04)
OpenJDK 64-Bit Server VM (AdoptOpenJDK)(build 25.212-b04, mixed mode)

Set the default version

If your Debian system has various versions of Java installed, you can check which one is the default by typing:

java -version

Use the update-alternatives command to change the default version:

sudo update-alternatives --config java

The result will resemble the following:

Output

There are 2 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
  1            /usr/lib/jvm/adoptopenjdk-8-hotspot-amd64/bin/java   1081      manual mode
  2            /usr/lib/jvm/java-11-openjdk-amd64/bin/java          1111      manual mode


Press <enter> to keep the current choice[*], or type selection number: 

A list of all installed Java versions will be shown to you. Press Enter after specifying the version number you want to be the default.

JAVA_HOME Environment Variable

Some Java applications determine the location of the Java installation using the JAVA_HOME environment variable.

Use the update-alternatives command to determine the location of Java's installation before setting the JAVA_HOME environment variable:

sudo update-alternatives --config java

These are the installation paths used in this example:

• OpenJDK 11 is located at /usr/lib/jvm/java-11-openjdk-amd64/bin/java
• OpenJDK 8 is located at /usr/lib/jvm/adoptopenjdk-8-hotspot-amd64/bin/java

Open the /etc/environment file once you have located the path of your desired Java installation:

sudo nano /etc/environment

Append the following line, assuming you want to set JAVA_HOME to OpenJDK 11.

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

You can log out and back in again to make changes take effect on your current shell, or you can execute the source command described below:

source /etc/environment

Check to see if the JAVA_HOMEenvironment variable was set properly:

echo $JAVA_HOME

The location of the Java installation should be displayed:

Output

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

Uninstall Java

Like any other package installed using apt, Java can be uninstalled.

Run these commands, for instance, to uninstall the default-jdk package:

sudo apt remove default-jdk

FAQs to Install Java on Debian 10 Linux

Conclusion

We hope this detailed tutorial helped you to install Java on Debian 1o.

If you have any queries, please leave a comment below and we’ll be happy to respond to them.