flake.nix

{
  description = "A Nix-flake-based Java development environment";

  inputs = {
    flake-utils.url = "github:numtide/flake-utils";
    nixpkgs.url = "github:NixOS/nixpkgs";
  };

  outputs =
    { self
    , flake-utils
    , nixpkgs
    }:

    flake-utils.lib.eachDefaultSystem (system:
    let
      javaVersion = 17;

      overlays = [
        (self: super: rec {
          jdk = super."jdk${toString javaVersion}";
          gradle = super.gradle.override {
            java = jdk;
          };
          maven = super.maven.override {
            inherit jdk;
          };
        })
      ];

      pkgs = import nixpkgs { inherit overlays system; };
    in
    {
      devShells.default = pkgs.mkShell {
        buildInputs = with pkgs; [ gradle jdk maven ];

        shellHook = ''
          ${pkgs.jdk}/bin/java -version
        '';
      };
    });
}