This is a set of Nix expressions for building Java packages (JARs). It already includes several common Java libraries and can be easily extended with more. For instance, the top 10 most popular Java libraries (as of March 2024) are all available:

• junit (as junit4)
• slf4j-api (as slf4j.api)
• guava
• mockito
• jackson-databind (as jackson.databind)
• commons-lang3 (as commons-lang)
• logback-classic (as logback.classic)
• commons-io
• lombok
• gson

To list available packages:

nix-env -qaPf . | sort

TODO: document buildJavaPackage. See examples/basic-project.nix.

TODO: document how to overlay an upgrade for one particular package. See examples/override-package.nix.

I am sick of NoClassDefFoundError.

The packages here are guaranteed to meet a minimum level of compatibility since they are compiled from source against each other.

Why not build with Ant/Maven/Gradle? All of the projects here have some other build system, and all of those build systems are ignored. The major Java build systems are deeply incompatible with the Nix way of doing things, since they insist on locating dependencies themselves rather than having them provided by an external package manager. See Misadventures Recompiling the Java Ecosystem from Source for more information about why Maven, specifically, would be a nightmare to support.

Java 9 Modules? Yes, modules are supported. However, at the moment the builder does not modularize executables, which means there isn't actually any run-time encapsulation protection. TODO: switch from CLASSPATH to --module-path for executables that support it.

OSGi? No. Most OSGi projects work just fine as normal JARs, which is the way this set of packages prefers to use them.