How to Install JAVA on Debian 11

Linux

Install Java on Debian 11 Bullseye

Java is a high level, robust, object-oriented and secure programming language.LTS releases such as JDK 17 arrive every three years. The last LTS release, JDK 11, was published in September 2018. New releases of Java arrive every six months.Few features of Java 17 are listed below.

• Making it easier to use various PRNG algorithms interchangeably in applications.
• Improved support for stream-based programming, providing streams of PRNG objects.
• Elimination of code duplication in existing PRNG classes.

In this article, we will show you how to install java on Debian 11 system.

Step 1: install Java

First we will update apt package index.

sudo apt update

then check if Java is already installed or not using following command.

java -version

output:

-bash: java: command not found

now we will install default open jre and jdk versions.

sudo apt install default-jre default-jdk

then check java version again

root@debian:~# java --version
openjdk 11.0.12 2021-07-20
OpenJDK Runtime Environment (build 11.0.12+7-post-Debian-2)
OpenJDK 64-Bit Server VM (build 11.0.12+7-post-Debian-2, mixed mode, sharing)

If you want to install Latest Java version, then use following command.

sudo apt install openjdk-17-jre openjdk-17-jdk 

output:

openjdk 17-ea 2021-09-14
OpenJDK Runtime Environment (build 17-ea+19-Debian-1)

Also Read -> How to Install LAMP stack on Debian 11 

step 2: set default java version

you can have multiple Java installations on one server. To configure which version is the default for use the following command.

sudo update-alternatives --config java

output:

There are 2 choices for the alternative java (providing /usr/bin/java).
  Selection    Path                                         Priority   Status
------------------------------------------------------------
* 0            /usr/lib/jvm/java-17-openjdk-amd64/bin/java   1711      auto mode
  1            /usr/lib/jvm/java-11-openjdk-amd64/bin/java   1111      manual mode
  2            /usr/lib/jvm/java-17-openjdk-amd64/bin/java   1711      manual mode
Press <enter> to keep the current choice[*], or type selection number: 1
update-alternatives: using /usr/lib/jvm/java-11-openjdk-amd64/bin/java to provide /usr/bin/java (java) in manual mode

Also Read -> How to Install php 8 on Debian 11 Bullseye

Step 3: set environment variable

Java applications often require JAVA environment variables to be set in the system.To run Java programs from anywhere,you need to set  $JAVA_HOME.

To set the variable, edit /etc/environment file as below.

nano /etc/environment

Add below line which is default install location of JAVA11.

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

save the file and exit and  also reload the file to apply the changes to your current session.

source /etc/environment

Next, verify that the environment variable is set

echo $JAVA_HOME

output:

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

That's it. Now you have successfully installed Java on Debian 11 system.

Also Read -> How to Install JAVA on Ubuntu 20 04