Setup JavaFX on NixOS

Dev Shell

Refer to NixOS Wiki, to enable JavaFX support, an override is required:

jdkWithFX = pkgs.openjdk.override {
  enableJavaFX = true;
};

The minimal flake.nix looks like:

{
  description = "Devshell for JavaFX.";
  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
  outputs = {
    self,
    nixpkgs,
  }: let
    system = "x86_64-linux";
    pkgs = import nixpkgs {inherit system;};
    jdkWithFX = pkgs.openjdk.override {
      enableJavaFX = true;
    };
  in {
    devShells.${system}.default = pkgs.mkShell {
      buildInputs = [ jdkWithFX ];
    };
  };
}

After creating this file, run nix develop to enter the dev shell.

Setup LSP in nixvim

Firstly, we need to enable nvim-lspconfig in nixvim as a framework for LSP.

plugins.lsp.enable = true;

Then, I choose to use jdtls as LSP of Java. Add the following code to enable it in nixvim:

plugins.lsp.servers.jdtls.enable = true;

Now, try to edit a Java file in the dev shell environment, but jdtls can not find JavaFX. To solve this issue, I use Gradle.

In the same level directory of flake.nix, create a file named build.gradle, then add the following content:

plugins {
  id 'application'
  id 'org.openjfx.javafxplugin' version '0.1.0'
}

repositories {
    mavenCentral()
}

javafx {
    version = "21"
    modules = [ 'javafx.controls', 'javafx.fxml' ]
}

Please ensure the version of javafx is compatible with the JDK.

Finally, restart the LSP, jdtls will find JavaFX and provide code completions.

References

NixOS Wiki

openjfx/samples