How to install multiple versions of jdk and specify a default?

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1

Is it possible to install multiple stable versions of the openjdk and specify a default version to link?

Ideally, I’d have 8 (for legacy work), 11, and 14 when that’s available. Specifying multiple versions in a buildEnv, however causes priority conflicts (e.g., for /bin/unpack200).

I can create a shell.nix, of course, as needed which bypasses this issue.

When I was using macports it had this feature where you can ‘activate’ a specific version of a port.

sudo port select --set python python34

But other versions were still usable (e.g., python33). They just wouldn’t be default.

So in the case of the jdk, is this achievable or not recommended?

2

This is what I do, and works pretty well for me. I even have a project where I need jdk8 and jdk11 side-by-side, but that also works pretty easily:

{ pkgs ? import <nixpkgs> {} }:

pkgs.mkShell {
  buildInputs = [
    // some other dependencies
  ];

  JAVA_8_HOME = "${pkgs.jdk}/lib/openjdk";
  JAVA_11_HOME = "${pkgs.jdk11}/lib/openjdk";
}

(the project knows how to use those environment variables to find the JDK’s)

2 Likes
3

Thanks @raboof, that is brilliant!