Jabba: A Java Version Manager
TLDR;
Try Jabba, an Open Source Tool for managing multiple Java versions in your system. It’s written in Golang. It has been inspired by nvm which manages Node versions
Video Version
Before going into the post, if you prefer videos over blogs, you can checkout this YouTube video, which has the same information as this blog post.
This blog post will be mostly the text version of the video :)
Longer Version
Do you work on Java projects? Do you have multiple Java versions across different projects? Yes? How do you manage it? No? You are probably lucky :P
In this blog post I want to talk about a dev tool called Jabba, which is a Java version manager. There are probably other alternatives, but Jabba was the first hit I got when I searched for Java version manager
https://github.com/search?utf8=%E2%9C%93&q=java%20version%20manager
Jenv was one alternative that I heard of. I guess their description didn’t help with getting them on the top of the GitHub search result but they have lots of stars on GitHub. I’ll probably try it in the future. Anyways, for this blog post, I’m going to focus on Jabba :)
Why?
I think the reason for the existence of such language version managers maybe a bit puzzling. I want to give a gist to those who might think “Why do I even need this?”
Now, I’m someone whose always trying to keep things - so I usually would love it if I just had to install one version of a compiler or interpreter - preferably the latest version and always be able to update whenever new versions come. I do that for my Golang installation. I always update to the latest actually. But then, why would I go and use something like a Java version manager or even Node version manager for my node projects sometimes.
The biggest thing to understand is - let’s say if I want to always use only one version and preferably the latest version, then, all the source code of my projects should be compatible with it and work with it. So, what I need to do is -
- Update to latest version of the language (compiler / interpreter etc)
- Update the source code if needed to keep it compatible with the language version
Now this is where the issue comes in. Sometimes it may not be easy to simply use a new version of the language with your source code. Your source code may need some changes to keep it compatible with the latest language version. In such cases, instead of spending time to make the source code compatible, the alternative is to go ahead and use multiple language versions for different projects. So, very old projects may be using older version because at the start of the project, it may have been the language version and maybe no one tried to spend time to upgrade the language version and probably the source code too. But when starting new projects, they would try to go with newer language versions. So, at the end, you end up having multiple language versions.
One good thing to note is that, many languages try to not have breaking changes in their language spec. Java rarely does breaking changes from what I know and I have heard that it’s one reason many people love Java. The same goes for Golang I think, except in one case where I noticed some breaking changes in Golang’s generated files (go.sum).
Now that I have told you one example of why would someone even need multiple versions, let’s move on to Jabba!
Jabba
Jabba is pretty straight forward to use. It’s written in Golang and you can get a single binary and put it anywhere and it will run. I use Mac OS and I installed it with this command
$ curl -sL https://github.com/shyiko/jabba/raw/master/install.sh | bash && . ~/.jabba/jabba.sh
For other ways to install or other OSes, go to https://github.com/shyiko/jabba and check installation methods
After installation, use jabba in the command line and it will help you with
it’s help instructions
$ jabba
Java Version Manager (https://github.com/shyiko/jabba).
Usage:
jabba [flags]
jabba [command]
Available Commands:
install Download and install JDK
uninstall Uninstall JDK
link Resolve or update a link
unlink Delete a link
use Modify PATH & JAVA_HOME to use specific JDK
current Display currently 'use'ed version
ls List installed versions
ls-remote List remote versions available for install
deactivate Undo effects of `jabba` on current shell
alias Resolve or update an alias
unalias Delete an alias
which Display path to installed JDK
Flags:
-h, --help help for jabba
--version version of jabba
Use "jabba [command] --help" for more information about a command.
Before using Jabba, I would recommend getting rid of any other JDK
installations, so that you have lesser confusions and also lesser other Java
binaries in your $PATH environment variable
To check what Java versions / variants you can install, just check using Jabba like this
$ jabba ls-remote
1.15.0
1.15.0-1
1.6.65
adopt@1.15.0-1
adopt@1.15.0-0
adopt@1.14.0-2
...
...
adopt@1.8.0-181
adopt@1.8.0-172
adopt-openj9@1.15.0-1
adopt-openj9@1.15.0-0
...
...
adopt-openj9@1.8.0-242
adopt-openj9@1.8.0-232
amazon-corretto@1.11.0-9.12.1
amazon-corretto@1.11.0-9.11.1
...
...
amazon-corretto@1.8.232-09.1
amazon-corretto@1.8.222-10.1
graalvm@20.3.0
graalvm@20.2.0
...
...
graalvm@1.0.0-6
graalvm@1.0.0-5
graalvm-ce-java11@20.3.0
graalvm-ce-java11@20.2.0
...
...
graalvm-ce-java8@1.0.0-6
graalvm-ce-java8@1.0.0-5
liberica@1.15.0
liberica@1.15.0-1
...
...
liberica@1.8.232-10
liberica@1.8.222
openjdk@1.15.0
openjdk@1.15.0-1
openjdk@1.14.0
...
...
openjdk@1.9.0
openjdk@1.9.0-4
zulu@1.16.0-0
zulu@1.15.0
...
...
zulu@1.7.60
zulu@1.7.55
As you can see, there are so many versions and variants available. You can choose one and then install it. For example, like this
$ jabba install openjdk@1.11.0-2
$ jabba install openjdk@1.15.0-1
Jabba has been inspired by nvm, so if you have
used nvm, you would find a similar experience with jabba :)
To check what are the installed Java versions, just run
$ jabba ls
openjdk@1.15.0-1
openjdk@1.11.0-2
To use a Java version, you can run
$ jabba use openjdk@1.11.0-2
$ java --version
openjdk 11.0.2 2019-01-15
OpenJDK Runtime Environment 18.9 (build 11.0.2+9)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.2+9, mixed mode)
$ which java
/Users/karuppiahn/.jabba/jdk/openjdk@1.11.0-2/Contents/Home/bin/java
$ jabba use openjdk@1.15.0-1
$ java --version
openjdk 15.0.1 2020-10-20
OpenJDK Runtime Environment (build 15.0.1+9-18)
OpenJDK 64-Bit Server VM (build 15.0.1+9-18, mixed mode, sharing)
$ which java
/Users/karuppiahn/.jabba/jdk/openjdk@1.15.0-1/Contents/Home/bin/java
You can also check where your JDK is installed
$ jabba ls
openjdk@1.15.0-1
openjdk@1.11.0-2
$ jabba which openjdk@1.15.0-1
/Users/karuppiahn/.jabba/jdk/openjdk@1.15.0-1
Also, when opening a new shell / terminal, to be able to set one default Java version, you can use the jabba alias like this
$ jabba alias default openjdk@1.15.0-1
default -> /Users/karuppiahn/.jabba/jdk/openjdk@1.15.0-1
$ jabba alias default
openjdk@1.15.0-1
So, every time you open a new shell, it will have the default Java version. You
can also use .jabbarc to store your Java version in your different
repositories, and then use jabba like this
$ echo "openjdk@1.15.0-1" > .jabbarc
$ jabba use
$ java --version
openjdk 15.0.1 2020-10-20
OpenJDK Runtime Environment (build 15.0.1+9-18)
OpenJDK 64-Bit Server VM (build 15.0.1+9-18, mixed mode, sharing)
Conclusion
Those were just some of the features of jabba. There are a few more. You can
check other features of jabba by checking it’s help :)
$ jabba --help
Jabba seems to be a pretty simple tool to use and mostly intuitive too. Let me know what you think!
If you have any questions or comments, do comment below :)