Linux

With a package manager:

sudo apt install openjdk-21-jdk

apt-get install -y wget apt-transport-https gnupg
wget -O - https://packages.adoptium.net/artifactory/api/gpg/key/public | apt-key add -
echo "deb https://packages.adoptium.net/artifactory/deb $(awk -F= '/^VERSION_CODENAME/{print$2}' /etc/os-release) main" | tee /etc/apt/sources.list.d/adoptium.list
apt-get update # update if you haven't already
apt-get install temurin-21-jdk

Manual installation:

In the example below we assume that the distribution is packed as a tar.gz archive. The example shows the archive name as of 21 January 2024, OpenJDK21U-jdk_x64_linux_hotspot_21.0.2_13.tar.gz

sudo mkdir -p /usr/lib/jvm
cd /usr/lib/jvm
sudo tar xf ~/Downloads/OpenJDK21U-jdk_x64_linux_hotspot_21.0.2_13.tar.gz

macOS

With HomeBrew:

# Untap AdoptOpenJDK first
brew untap AdoptOpenJDK/openjdk

# If you want to download latest version
brew install --cask temurin

# To install specific version
brew tap homebrew/cask-versions
brew install --cask temurin21

Manual installation:

Download the correct distribution/version of choice from AdoptOpenJDK . Install the same way as normal programs.

Windows

Install with the Windows Package Manager:

First install the winget

winget install Microsoft.OpenJDK.21

Manual installation:

Download the correct distribution/version of choice from AdoptOpenJDK . Install the same way as normal programs,

Linux

JAVA_HOME Define JAVA_HOME first. That will help Java, but also tell other programs to find the desired Java version.

export JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64 1
export JAVA_HOME=/usr/lib/jvm/temurin-17-jdk 2

PATH Prepend the directory under JAVA_HOME to your path, so all java related programs, such as java , javac, jar etc can be found, by just typing the name.

export PATH=${JAVA_HOME}/bin:$PATH

To avoid having to do this every time you start the command-line, add the commands to your _/.bashrc//.zshrc script file, at the bottom.

export JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64
export PATH=${JAVA_HOME}/bin:$PATH

To switch Java versions use the following command:

sudo update-alternatives --config java

macOS

These instructions will guide you to setup the correct environment on macOS and to make it easy to switch between Java versions.

/usr/libexec/java_home
/usr/libexec/java_home -V

The first command lists the most recent version of Java on your system The second command lists all installed versions of Java on your system

We can now setup an environment to easily switch between Java versions and later on even launch most IDEs with the intended Java version. The only thing we need to do for this is set the JAVA_HOME environment variable to link to the correct Java version.

export JAVA_HOME=<path_to_java_home>

Where the <path_to_java_home> can be obtained by the command above with the -V parameter.

echo $JAVA_HOME

However instead of hardcoding the path it is better to retrieve the path while setting the environment.

export JAVA_HOME=$(/usr/libexec/java_home)

$() means that the invocation between parenthesis is resolved first.

This sets the correct Java environment for your current Terminal session. When opening a new terminal the default Java environment will be active again. To make switching between Java versions in the terminal easier we can set-up what is called an alias. An alias is basically a shortcut, you specify the keyboard shortcut and which commands should be executed. We want these aliases to always be available, for this we need to let the terminal know to load our aliases on startup. Depending on the type of terminal you are using, we need the specify the aliases at different places.

Since macOS Catalina (10.15) the default shell (which is used by the terminal) is ZShell (zsh). This means we can specify our aliases in either .zshrc or in .zprofile in our home directory. We suggest to create an additional configuration file .java_setup in your home directory.

# Include java environment setup
source .java_setup

# Set your default JAVA_HOME
export JAVA_HOME=$(/usr/libexec/java_home -v 17.0.6)

alias j11="export JAVA_HOME=`/usr/libexec/java_home -v 11.0.12`; java -version"
alias j17="export JAVA_HOME=`/usr/libexec/java_home -v 17.0.6`; java -version"
alias j21="export JAVA_HOME=`/usr/libexec/java_home -v 21.0.2`; java -version"

# Add maven to path
export PATH=/Applications/maven/apache-maven-3.9.0/bin:$PATH

We now need to either restart the terminal for the aliases to take effect or source the .zshrc file:

source ~/.zshrc

We can now check that switching between versions works:

java -version
j11
j17
j21

Check that the default Java version is correct Check that switching between versions works Check that switching between versions works Check that switching between versions works

Now we have set-up a way to easily switch between Java versions in the terminal.

Windows

Java should already be added to the path by the installer, as it is a default setting during installation.

Linux

Install with package manager:

sudo apt install maven

Install manually:

Fetch a fresh copy of Apache Maven from the website.

To install it, do (example uses version 3.9.6 as of 2024-01-21)

cd /usr/share
sudo rm -fr maven
sudo tar xf ~/Downloads/apache-maven-3.9.6-bin.tar.gz
sudo ln -sf apache-maven-3.9.6/ maven
cd /usr/bin
sudo ln -sf ../share/maven/bin/mvn .

Once this is done, entering mvn --version should produce output.

macOS

Install with HomeBrew:

brew install maven

Install manually:

Fetch a fresh copy of Apache Maven from the website. Unzip the archive at an appropriate location (e.g. /Applications). Make sure to put maven on the path, see java_setup.

Once this is done, entering mvn --version should produce output.

Windows

Install with Chocolately:

choco install maven

Install manually:

Linux

You can either install Netbeans from Ubuntu Software (Snap) or download the binaries.

To install the binaries of Apache NetBeans on Ubuntu simply fetch the binary as zip file and unpack it, then either add the contained bin directory to the path, or make a wrapper netbeans command in your personal ~/bin directory.

For my installation I simply used the binaries, in the zip file, and install it in the traditional (as in same directories as the installer would) /usr/local. /opt is also a good choice as installation directory.

cd /usr/local
sudo unzip ~/Downloads/netbeans-20-bin.zip
sudo mv netbeans{,-21}

For extra creature comfort, add a simple netbeans script to your path

#!/usr/bin/env bash
/usr/local/netbeans-20/bin/netbeans "$@" & 1

Then make that script executable with chmod +x netbeans.

NetBeans IDE should now be runnable from the command line (fine for me) as well as from the menu.

macOS

It is possible to install Netbeans by downloading the installer, manual extracting the binaries or by using HomeBrew.

Installing with the installer:

brew install --cask netbeans

Installing the binaries manually, see installation guidelines for maven on MacOS.

As an extra we can start Netbeans from the command-line using the Java version we want to use.

We do this by adding an executable file to the PATH so we can start Netbeans from the terminal with the correct Java version.

cd /usr/local/bin 1
touch netbeans 2
echo \"/Applications/NetBeans/Apache\ NetBeans\ 21.app/Contents/Resources/NetBeans/netbeans/bin/netbeans\" --jdkhome
\$JAVA_HOME \$\* \& > netbeans 3
chmod +x netbeans 4

As you can see, when invoking it this way, you can inform Netbeans about which java version to use (as set in your JAVA_HOME environment variable). Furthermore you can pass the project name as a parameter (defined by $*`) so you don’t need to open the project manually anymore in NetBeans. Finally the & means that NetBeans runs as a background process without blocking your Terminal session, so your Terminal session is immediately available again.

j17
netbeans myProject

Windows

Other IDE’s

We use NetBeans IDE as default. We might not be able to answer any support questions on other IDE’s. You are free to choose your own Integrated Development Environment (IDE). An IDE allows you to write, compile, run and debug your programs in one place. Popular choices are: