Java

This article is about Java, the programming language.

JDK options

Your default choice should probably be to install jdk11, which is an alias for openjdk11. If you're in a server environment, go for jdk11_headless. Java 11 is the currently-maintained LTS version of OpenJDK as of Oct 2019.

As you might expect, though, many flavors of Java are available in NixOS.

OpenJDK, by far the most popular non-Oracle JVM implementation
- openjdk8[_headless] for a legacy Java 8 VM required by some older apps
- openjdk11[_headless], the currently-supported LTS version of OpenJDK
- openjdk12[_headless], the current version of OpenJDK
AdoptOpenJDK, prebuilt binaries for OpenJDK
- adoptopenjdk-bin points to the latest version of AdoptOpenJDK, which is version 11 at the time of writing.
- adoptopenjdk-jre-bin is available if you want to avoid downloading the compiler and only require the runtime environment.
JetBrains JDK (jetbrains.jdk), a fork of OpenJDK with modifications made by JetBrains
Oracle's JDK (oraclejdk), only version 8 is available.

Using Oracle JDK instead of Open JDK

Almost all Java packages in nixpkgs use Open JDK in form of a jre dependency. If you use Oracle JDK and also want other applications to use it, you can simply tweak your .nixpkgs/config.nix so that your desired application uses Oracles JDK or JRE.

Example with UMLet with JRE

{
  allowUnfree = true;
  packageOverrides = pkgs: rec {
    umlet = pkgs.umlet.override {
      jre = pkgs.oraclejre8;
    };
  };
}

Better font rendering

By default java does not enable antialiasing for font rendering. By exporting environment variables, this can be fixed:

$ export _JAVA_OPTIONS='-Dawt.useSystemAAFontSettings=lcd'

More options can be found in the archlinux wiki