Java

Setup (debian)

• Update the package index; check if Java is already installed;

$ sudo apt update
Hit:1 http://archive.ubuntu.com/ubuntu focal InRelease
[...]
Building dependency tree       
Reading state information... Done
$
$ java --version
Command 'java' not found, but can be installed with:

sudo apt install openjdk-11-jre-headless  # version 11.0.16+8-0ubuntu1~20.04, or
sudo apt install default-jre              # version 2:1.11-72
sudo apt install openjdk-16-jre-headless  # version 16.0.1+9-1~20.04
sudo apt install openjdk-17-jre-headless  # version 17.0.4+8-1~20.04
sudo apt install openjdk-8-jre-headless   # version 8u342-b07-0ubuntu1~20.04
sudo apt install openjdk-13-jre-headless  # version 13.0.7+5-0ubuntu1~20.04

• Install the default Java Runtime Environment (JRE), which will install the JRE from OpenJDK 11

$ sudo apt install default-jre
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following additional packages will be installed:
[...]
Running hooks in /etc/ca-certificates/update.d...
done.
done.
$ java --version
openjdk 11.0.16 2022-07-19
OpenJDK Runtime Environment (build 11.0.16+8-post-Ubuntu-0ubuntu120.04)
OpenJDK 64-Bit Server VM (build 11.0.16+8-post-Ubuntu-0ubuntu120.04, mixed mode, sharing)
$

• You may need the Java Development Kit (JDK) in addition to the JRE in order to compile and run some specific Java-based software

$ sudo apt install default-jdk
[...]
$
$ javac -version
javac 11.0.11
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