Manifold F.A.Q.s - Frequently Asked Questions (and Answers)

Common Questions • Getting Help • Troubleshooting

Common Questions

Q: Does Manifold support Java 21? 17? 8?

Manifold fully supports all LTS versions since JDK 8, which includes 8, 11, 17, and 21. Additionally, manifold works with the latest non-LTS version. Manifold also fully supports the Java Platform Module System (JPMS).

Q: Manifold is somehow using Java internal APIs to do its magic. Could it break in a future version of Java?

Unlikely. Java internal APIs can and do change from version to version, sometimes dramatically, however Manifold always adjusts to changes ahead of Java releases. To date, Manifold has adapted to eight major Java versions since its debut, always well in advance of Oracle’s official release schedule.

Q: Doesn’t Kotlin do all this already?

No. While there are bits of overlap such as properties, Kotlin does not have most of Manifold’s features. Notably, it does not offer anything similar to Manifold’s core feature, the type manifold, which is the basis for manifold-sql, manifold-json, manifold-graphql, manifold-xml, and a multitude of others. In addition, most of manifold’s extensions to the Java language are not present in Kotlin, these include:

Importantly, Kotlin is an entirely separate language from Java, while Manifold is a compiler plugin that supplements Java with new features. Add Manifold to any Java project and incorporate features of your choosing.

Q: Is Manifold free?

Yes, the Manifold project is open source and publicly available on github, free for use via Apache License 2.0.

The Manifold plugins for IntelliJ and Android Studio are also open source and freely available.

Q: Does Manifold work with Maven? Gradle?

Yes. Please refer to the Maven and Gradle sections of the Setup instructions detailed in the subproject[s] you are using.

Q: Does Manifold provide IDE support?

Yes. The Manifold plugin provides comprehensive support for IntelliJ IDEA and Android Studio.

Download / Update the plugin directly from within the IDE:

Settings ➜ Plugins ➜ Marketplace ➜ search: Manifold

Note: The IDE notifies you within 24 hours when an update is available and gives you the opportunity to sync.

Q: Do I need a license for the IntelliJ plugin?

No. The plugin is no longer commercial and is available for free from JetBrains Marketplace.

Q: How do I get manifold-fill-in-blank working with my project?

Add the manifold-fill-in-blank dependency[s] to your project along with the -Xplugin:Manifold javac argument, the setup is sensitive to the version of Java you are using, generally whether you are using Java 8 or 9+. See the Setup docs within the manifold-fill-in-the-blank subproject for complete instructions.

Getting Help

Q: Where can I find help?

Discussions Join our Discord server to start a discussion, ask questions, provide feedback, etc.

Report A Bug The Manifold project uses github issues to track bugs, features, and other requests. If you discover a bug, have a feature request, or an idea go here and let it be known. Expect a response within 24 hours.

Private E-mail If your question or issue is more pressing or confidential, don’t hesitate to send an email to info@manifold.systems.

Q: I’ve read the docs page. Can I learn more about Manifold elsewhere?

Links to recently published Manifold articles are available on the Articles page. There is always another article on the way, check back for more.

Troubleshooting

Q: I updated to the latest Manifold IntelliJ plugin and now IntelliJ is complaining with error messages. What’s wrong?

You probably need to update your project dependencies to use the latest manifold release. If your project’s dependencies are out of sync, the plugin tells you which version of manifold you need with in a warning message when you load your project. You can find the latest releases here.

Important: If you are using Maven or Gradle, you must update your build files – do not change the Module dependencies from IntelliJ’s UI. Please refer to the Maven and Gradle sections of the Setup instructions detailed in the subproject[s] you are using.

Please make some noise if you can’t get it working, chances are you’re not alone and help will arrive soon.

Q: I defined some useful extension methods, but they aren’t showing up in my other project. How can I share them as a dependency?

The module with your extension methods must declare that it should be processed for extension methods. Do that with the Contains-Sources JAR manifest entry. For instance, from Maven:

  <manifestEntries>
      <!--class files as source must be available for extension method classes-->
      <Contains-Sources>java,class</Contains-Sources>
  </manifestEntries>

Please see the documentation for making extension libraries.

Q: I defined a new extension class with some extension methods, IntelliJ flags usage of them as errors. What’s wrong?

Sometimes IntelliJ’s cache is out of sync with extensions. Generally, whenever IntelliJ’s editor displays an error for legal usage of a manifold feature, you can often remedy the problem by making a small change at the use site and then undoing the change. Failing that, it is best to close and reload the project. Please report errors of this nature as issues on manifold’s github repo.

Q: Who uses Manifold?

A sampling of companies currently using manifold: