# Remove hardcoded dependency of SBT on JDK8?
**URL:** https://discourse.nixos.org/t/remove-hardcoded-dependency-of-sbt-on-jdk8/9053
**Category:** Development
**Created:** [September 18, 2020, 12:42pm UTC](https://discourse.nixos.org/t/remove-hardcoded-dependency-of-sbt-on-jdk8/9053 "2020-09-18T12:42:11Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@bobismijnnaam](https://discourse.nixos.org/u/bobismijnnaam)
#### Post date: [September 18, 2020, 12:42pm UTC](https://discourse.nixos.org/t/remove-hardcoded-dependency-of-sbt-on-jdk8/9053/1 "2020-09-18T12:42:11Z")
Currently SBT seems to have a harcoded preference for JDK8. See here: [https://github.com/NixOS/nixpkgs/blob/360e0fae7e205d3c63a21a11791e15dfa5079cb9/pkgs/development/tools/build-managers/sbt/default.nix#L16](https://github.com/NixOS/nixpkgs/blob/360e0fae7e205d3c63a21a11791e15dfa5079cb9/pkgs/development/tools/build-managers/sbt/default.nix#L16). The `conf/sbtopts` file this is written to is loaded by SBT on start-up, so unless JAVA\_HOME is passed as an argument to SBT, JDK8 is used.
As far as I understand it SBT is designed to grab the java it works with from the PATH. So I was very confused when I loaded up JDK11 in `nix-shell` and SBT still used JDK8, even though `which java` reported the JDK11 Java.
So my question is: is there a good reason for this hardcoded preference? Because if someone did this with a good reason, or if it is convention or something, I can live with it/work around it. Or should I change this and make a PR with this hardcoding removed? It seems like the current behavior is somewhat unconventional, but that might just be me. (I also thought of sending the package maintainer an e-mail but I wasn’t sure if that’s appropriate so I’m first asking here…)
---
### Author:  [@NobbZ](https://discourse.nixos.org/u/NobbZ)
#### Post date: [September 18, 2020, 1:15pm UTC](https://discourse.nixos.org/t/remove-hardcoded-dependency-of-sbt-on-jdk8/9053/2 "2020-09-18T13:15:20Z")
It uses whatever Java gets passed in.
Feel free to `sbt.override { jre = pkgs.jdk11; }` or whatever is necessary for you.
---
### Author:  [@bobismijnnaam](https://discourse.nixos.org/u/bobismijnnaam)
#### Post date: [September 18, 2020, 1:19pm UTC](https://discourse.nixos.org/t/remove-hardcoded-dependency-of-sbt-on-jdk8/9053/3 "2020-09-18T13:19:11Z")
Hmm, what if I just want SBT to use whatever’s on the path? Now that I see myself typing this, that sounds like it goes against nix’s philosophy… I’ll use your workaround, thanks.
---
### Author:  [@fzakaria](https://discourse.nixos.org/u/fzakaria)
#### Post date: [September 18, 2020, 2:58pm UTC](https://discourse.nixos.org/t/remove-hardcoded-dependency-of-sbt-on-jdk8/9053/4 "2020-09-18T14:58:33Z")
If SBT is like maven; it will defer to JAVA\_HOME before taking the Java if uses itself.
For my programs, I set JAVA\_HOME in my nix shell to the desired JDK.
This let’s maven run with whatever JDK it uses but compile/run my application with the desired JDK.
---
### Author:  [@raboof](https://discourse.nixos.org/u/raboof)
#### Post date: [September 20, 2020, 11:09am UTC](https://discourse.nixos.org/t/remove-hardcoded-dependency-of-sbt-on-jdk8/9053/5 "2020-09-20T11:09:04Z")
> [@bobismijnnaam](#):
>
> unless JAVA\_HOME is passed as an argument to SBT, JDK8 is used.
You might be interested to know that since [jdk: point attributes without version suffix to latest by doronbehar · Pull Request #89731 · NixOS/nixpkgs · GitHub](https://github.com/NixOS/nixpkgs/pull/89731) it has moved to Java 14 by default.
---
### Author:  [@bobismijnnaam](https://discourse.nixos.org/u/bobismijnnaam)
#### Post date: [September 20, 2020, 12:08pm UTC](https://discourse.nixos.org/t/remove-hardcoded-dependency-of-sbt-on-jdk8/9053/6 "2020-09-20T12:08:27Z")
Okay, I’m probably making a very noob mistake (and I should probably have posted this thread in the “Learn” section, sorry), but I can’t get the following to work:
```auto
{ pkgs, ... }:
{
imports = [
./vim.nix
];
home.packages = with pkgs; [
fortune
xclip
graphviz
jdk11
sbt.override { jre = pkgs.jdk11; }
];
}
```
This file is then imported in my main `home.nix`. This gives me an error:
```auto
error: The option value `home.packages.[definition 1-entry 5]' in `~/commandLine.nix' is not of type `package'.
(use '--show-trace' to show detailed location information)
```
It looks like the `sbt.override` line is the problem. I thought `.override` returned a package, but it looks like I don’t get it after all. Maybe the `.override` pattern is meant for overlays, but that sounds like a heavyweight example for “just” changing one dependency (maybe I’m underestimating if that’s a big deal or not). Do I need to start using overlays or am I misunderstanding `.override`?
I also tried referring directly to `sbt` in `` so I could pass in the arguments for the package manually but I couldn’t get the path right…
EDIT:
I searched and read a bit more about overlays and came up with the following:
```auto
{ config, pkgs, ... }:
let sbtOverlay = self: super:
{
sbt = super.sbt.override { jre = super.jdk11; };
};
in
{
nixpkgs.overlays = [sbtOverlay];
// rest of config
}
```
And then in my sub `.nix` files I just refer to SBT. Not sure what to do now if I want to have differently versioned SBT’s (probably tweak JAVA\_HOME), but this works fine for now. If there’s a shorter/more elegant way I’m still very curious to hear.
---
### Author:  [@symphorien](https://discourse.nixos.org/u/symphorien)
#### Post date: [September 20, 2020, 1:47pm UTC](https://discourse.nixos.org/t/remove-hardcoded-dependency-of-sbt-on-jdk8/9053/7 "2020-09-20T13:47:22Z")
You need to put parens like this:
```auto
{ pkgs, ... }:
{
imports = [
./vim.nix
];
home.packages = with pkgs; [
fortune
xclip
graphviz
jdk11
(sbt.override { jre = pkgs.jdk11; })
];
}
```
Otherwise nix parses like this:
```auto
{ pkgs, ... }:
{
imports = [
./vim.nix
];
home.packages = with pkgs; [
fortune
xclip
graphviz
jdk11
(sbt.override)
({ jre = pkgs.jdk11; })
];
}
```
and neither `sbt.override` nor `jre = pkgs.jdk11; }` are packages.