DEV Community

Marcos Maia
Marcos Maia

Posted on • Edited on

Install and manage multiple Java versions on Linux using alternatives

On this post, I will guide you on installing Java on your development Linux machine. I decided to do this post after getting some questions on how do I manage multiple java versions in my Development environments if I use something to manage it like Sdkman, which I don't, in this post I will explain why.

Being in this industry for over 20 years I have developed software and scripts in many different languages like JavaScript, Pascal, Go, Python and others but I am mainly a passionate Java developer and I am committed to helping other colleagues to start programming in Java and help to demystify the fallacy that Java is complex or difficult to start. Java is the most used programming language for developing complex and enterprise software and it has by far the better ecosystem with it's available libraries, IDEs and tooling.

My preferred development environment is Linux so I'd rather use Linux alternatives to manage java SDK installations as it's built-in in Linux and allow you to manage not only java but any other binaries you want to manage and make accessible in your command line when using Linux. I will guide you to the process of installing Java 11 and running your first Hello World application using it.

The full installation process will be using the command line. So let's start, open a terminal console and cd to your preferred working directory.

  • Make sure to have wget installed.


sudo apt update && sudo apt install wget


Enter fullscreen mode Exit fullscreen mode
  • Download openjdk:


wget https://download.java.net/openjdk/jdk11/ri/openjdk-11+28_linux-x64_bin.tar.gz


Enter fullscreen mode Exit fullscreen mode

Can check for updated java 11 versions here: https://jdk.java.net/java-se-ri/11

  • Once download finished, add permissions:


chmod +x openjdk-11+28_linux-x64_bin.tar.gz


Enter fullscreen mode Exit fullscreen mode
  • Create folder where jdk will be installed


mkdir /usr/lib/jvm/open-jdk-11


Enter fullscreen mode Exit fullscreen mode
  • Extract it to /usr/lib/jvm/open-jdk-11 folder you have just created.


tar -xzf ./openjdk-11+28_linux-x64_bin.tar.gz -C /usr/lib/jvm/open-jdk-11 --strip-components=1


Enter fullscreen mode Exit fullscreen mode
  • Update alternatives to add java, javac, jshell and jar

    • list installed version


update-alternatives --list java


Enter fullscreen mode Exit fullscreen mode
  • configure java installation


sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/open-jdk-11/bin/java 1


Enter fullscreen mode Exit fullscreen mode
  • configure javac installation


sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/open-jdk-11/bin/javac 1


Enter fullscreen mode Exit fullscreen mode
  • configure jar installation


sudo update-alternatives --install /usr/bin/jar jar /usr/lib/jvm/open-jdk-11/bin/jar 1


Enter fullscreen mode Exit fullscreen mode
  • configure jshell installation


sudo update-alternatives --install /usr/bin/jshell jshell /usr/lib/jvm/open-jdk-11/bin/jshell 1


Enter fullscreen mode Exit fullscreen mode
  • Test installation, get java version:


java -version


Enter fullscreen mode Exit fullscreen mode
  • Test installation using jshell


jshell


Enter fullscreen mode Exit fullscreen mode
  • Type in


System.out.println("Hello World");


Enter fullscreen mode Exit fullscreen mode
  • Hit Ctrl + D to exit.

If you have multiple versions of java installed using this same process above, you can just switch between them using alternatives,

  • Display installed versions of java


sudo update-alternatives --display java


Enter fullscreen mode Exit fullscreen mode
  • Config the version you want to use:


sudo update-alternatives --config java


Enter fullscreen mode Exit fullscreen mode

Adding a new version and switching between them

Based on some comment suggestions I decided to extend the post to have a second version installed and show explicitly how to switch between them.

Lately I've been using Azul JVMs mostly so this time I will download the latest LTS Java 17 Open JDK from Azul

  • Download it with curl, I am placing it in my $HOME/tmp file:


curl -L https://cdn.azul.com/zulu/bin/zulu17.32.13-ca-jdk17.0.2-linux_x64.tar.gz > ~/tmp/zulu17.32.13-ca-jdk17.0.2-linux_x64.tar.gz


Enter fullscreen mode Exit fullscreen mode

Cd in the folder where you downloaded it.

  • Create folder where jdk will be installed


sudo mkdir /usr/lib/jvm/azul-open-jdk-17


Enter fullscreen mode Exit fullscreen mode
  • Extract it to /usr/lib/jvm/azul-open-jdk-17 folder you have just created.


sudo tar -xzf ./zulu17.32.13-ca-jdk17.0.2-linux_x64.tar.gz -C /usr/lib/jvm/azul-open-jdk-17 --strip-components=1


Enter fullscreen mode Exit fullscreen mode
  • Check the config options for java


sudo update-alternatives --config java


Enter fullscreen mode Exit fullscreen mode

You will see a list of configured java in alternatives, the new one is not there so we need to register it like we did in the beginning of this article, let's do it for java and javac, make sure to check the Selection number and add the new one to the next available, hit enter to continue with the current version before progressing, let's now register the new one we downloaded.

Java versions installed alternatives

  • configure java installation


sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/azul-open-jdk-17/bin/java 2


Enter fullscreen mode Exit fullscreen mode

The number in the end is the priority you can choose which one fits your goals better, by default the highest priority will be picked(lower number).

  • Repeat for javac, check the installed javac with sudo update-alternatives --config javac and then configure it with next available Reference.


sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/azul-open-jdk-17/bin/javac 2


Enter fullscreen mode Exit fullscreen mode
  • configure jar installation


sudo update-alternatives --install /usr/bin/jar jar /usr/lib/jvm/azul-open-jdk-17/bin/jar 2


Enter fullscreen mode Exit fullscreen mode
  • configure jshell installation


sudo update-alternatives --install /usr/bin/jshell jshell /usr/lib/jvm/azul-open-jdk-17/bin/jshell 2


Enter fullscreen mode Exit fullscreen mode

Now that you have the new JDK installed and configured you can easily switch between versions using:



sudo update-alternatives --config java


Enter fullscreen mode Exit fullscreen mode

Pick the number of the version you want from the Selection list.

Type in the Reference number for the one you want to be used from the displayed list and check with java -version the same can be done for, javac, jshell, jar or any other tools you want to manage multiple versions using alternatives on linux.

You can now pick the option you want from the available list. That's it, you're done and have a working local development java environment ready to go.

If you want to quick start with creating an API in Java using Spring Boot, make sure you have git and maven installed(sudo apt install git && sudo apt install maven) and check out this Spring Boot Crash Course, it's quite easy and quick to follow.

Top comments (14)

Collapse
 
katarman profile image
katarman

Hello thank for the article. How can I have multiple versions of JDK and Java ?
All the Linux distro have open-jdk in /etc/alternatives. Can I have jdk 11 and jdk 8 tohether?
Also I want to have the JDK 8 in /usr and a PATH variable java_home or java8 in system varibles, but I understand that the only way is to add variable in .bashrc.
Can you make it clear ?
Thank you in advance

Collapse
 
thegroo profile image
Marcos Maia

I have added details on the article with JDK 17 and how to switch between versions using alternatives.

Collapse
 
samprogramiz profile image
Samuel Owino 🇰🇪 🌍📱👨🏿‍💻🔭🌌 • Edited

If you installed and configured an additional version in the guides, could have been super helpful because that's the whole point - "working with multiple versions of java", otherwise it's just another "How to install java in Linux - Tutorial"

Still forced to just work with /etc/environment | $PATH update

Collapse
 
thegroo profile image
Marcos Maia

Hi, I followed your suggestion and added newest LTS 17 at the end of the post with instruction on how to switch between them. Hope it helps.

Cheers

Collapse
 
varunraje profile image
Varun Deshpande

How to configure open jdk 8 with this?

Collapse
 
thegroo profile image
Marcos Maia

The process is the same, you just have to adjust the paths in your local computer.

Collapse
 
sachajw profile image
Sacha Wharton

This is amazing! Thank you Marcos for this post!

Collapse
 
imadoor profile image
imadoor

Just what I was looking for. Thanks for sharing!

Collapse
 
thegroo profile image
Marcos Maia

I am glad it helped.

Collapse
 
hectorhugocc profile image
Hector Hugo

I have a problem. Using the 'echo $ PATH' command returns me a value but when reviewing the 'etc/environment' file you see another value. The same goes for the JAVA_HOME variable. Could you tell me what it is? Thanks for the support.

Collapse
 
thegroo profile image
Marcos Maia

Hum.... most likely you have in one of these files under your $HOME folder: .bash_profile, .bashrc, .zshrc or similar a configuration setting the $JAVA_HOME specifically to an existing installation? If you have I would recommend you to remove the entry and source the file or restart / login again to see if it's gone. In most cases you don't really need a $JAVA_HOME hardcoded in your profiles(with some exceptions).

If you type only env in your terminal you should see all existent variables in your machine.

Collapse
 
binarydiver profile image
Jason

It was good working!
Thanks a lot.

Collapse
 
punitkulal profile image
Punit Kulal

Great, helped me learn about alternatives in linux as well

Collapse
 
hophiducanh profile image
Ho Anh

I've just added more details. Check out here: github.com/logbasex/coding-notes/b...