Bring back the bundling a java app tutorial

[allanday]

We used to have a tutorial on bundling a java app, but dropped it when we moved the docs - the tutorial wasn't getting maintained and had got out of date.

We might want to bring the tutorial back, although we'd need to make sure that it got maintained in the future.

The latest version of the tutorial can be seen here:

https://github.com/flatpak/flatpak.github.io/blob/81bb006fd96b9a13170bd876316eb5a4eb48244b/source/bundling-a-java-app.html.haml.markdown

[btreut]

the tutorial wasn't getting maintained and had got out of date.

what exactly is out of date with it?

I find it very interesting as a template for some other Java app I would like to package in flatpak for endless OS. I'm a newby to endless/flatpak/containers, but I have some decades of experience with *ix and Linux ...

[allanday]

what exactly is out of date with it?

I can't remember exactly... if someone could run through the tutorial using the latest flatpak and runtimes, and let us know if they hit any issues or not, that would be really helpful!

[btreut]

I'll try my best, but I am a complete newbie to flatpak/containers/Linux namespaces, so give me some time.

Hello World is a little bit too simplistic to learn something and what I would really like to see as flatpak is (mediathekview, which has additional dependencies. I currently do not have any clue how to resolve these dependencies within a flatpak build environment. I know how to resolve them with apt on my Debian (siduction) build system, but I fear that these would not be available within the build environment.

See also the comments to the original pull request.

[allanday]

I've checked the old tutorial. Some of the things that would need to be changed:

• Don't reproduce generic steps or information from the rest of the docs
• Use flatpak-builder
• Write it as general documentation rather than a specific example/tutorial

Please could you explain how to bundle a software relying on Java with Flatpak by using a fat JAR in input? I would like to use Flatpak with Apache Ant in Java Native Deployment Toolkit:
http://tuer.sourceforge.net/en/documentation/#jndt

Do I simply have to adapt the following command line?

flatpak build sweethome3d-flatpak cp -ra SweetHome3D-5.2/* /app/SweetHome3D

Is the symbolic link necessary? The .desktop file directly calls /app/SweetHome3D/SweetHome3D, is it intended? Where is used /app/bin then?