If you’ve ever tried contributing to multiple open-source Java projects, you’ve probably run into this: Project A needs Java 8, Project B screams for Java 17, and Project C? It says, “Java 21 or I won’t even compile.”

At this point, you’ve got two options:

1. Cry softly into your coffee mug, or
2. Use SDKMAN!, the magical version manager for the JVM world.

Let’s go with option two. It’s less soggy.

What is SDKMAN!?

SDKMAN! stands for Software Development Kit Manager. It’s a command-line tool that lets you easily install, switch, and manage multiple versions of Java, Maven, Gradle, and a bunch of other developer tools.

If you’ve ever used nvm for Node.js or pyenv for Python, SDKMAN! is like that—except it’s for Java tools and doesn’t make you question your life choices every time you switch versions.

Why Open Source Contributors Love It

When you contribute to open source, you jump across repositories faster than your Wi-Fi disconnects on a Zoom call. Every project may need a different setup—different Java, different Maven, maybe even different Gradle.

SDKMAN! lets you switch environments instantly:

sdk use java 17.0.10-tem
sdk use maven 3.9.9

and you’re done.

No more messing with .bashrc or /usr/libexec/java_home. No more “works on my machine” nightmares. SDKMAN! keeps your setup clean and your sanity intact.

Installing SDKMAN! (Mac & Linux)

For macOS and Linux users:

You just need curl and bash, no wizardry required.

curl -s "https://get.sdkman.io" | bash

Then restart your terminal or run:

source "$HOME/.sdkman/bin/sdkman-init.sh"

To verify the installation:

sdk version

You should see something like SDKMAN 5.x.x smiling back at you.

Installing Java with SDKMAN!

You can see all available Java versions with:

sdk list java

To install one, for example Java 17 (Temurin distribution):

sdk install java 17.0.10-tem

To switch to it:

sdk use java 17.0.10-tem

Want it as default every time your terminal opens?

sdk default java 17.0.10-tem

Boom. Your environment is clean, consistent, and smells like freshly brewed coffee.

Pro tip: If you work on multiple projects, you can add a .sdkmanrc file inside each project folder specifying which Java and Maven version to use:

java=17.0.10-tem
maven=3.9.9

Then simply run:

sdk env init

and SDKMAN! switches everything automatically.

Installing Maven with SDKMAN!

SDKMAN! doesn’t stop at Java. It’s also your friend for Maven.

To see what’s available:

sdk list maven

Install your favorite version:

sdk install maven 3.9.9

Switch between versions easily:

sdk use maven 3.8.8

Set a default:

sdk default maven 3.9.9

Why This Rocks for Open Source

Let’s be real, open source is messy. Every project has its quirks. But SDKMAN! lets you hop between projects without breaking your entire dev setup.

You can:

• Reproduce build environments exactly as maintainers intended -Test your contributions across multiple JDKs
• Avoid the “works on my machine” curse
• Impress your fellow contributors with your wizard-like version switching skills

It’s a tiny tool that makes you a huge amount more productive.

Quick Troubleshooting Tips

Command not found? Make sure your shell rc file sources SDKMAN:

source "$HOME/.sdkman/bin/sdkman-init.sh"

• Version switching not working? Check your .sdkmanrc file and rerun sdk env.
• Still broken? Try restarting your terminal. Works 80% of the time, every time.

Final Thoughts

SDKMAN! is the kind of tool that makes you wonder why you didn’t use it earlier. It saves time, keeps your system clean, and lets you focus on the fun part writing code and contributing to open source instead of fighting environment setups.

Now go forth, install SDKMAN!, and bring harmony to your Java universe.