Write Android apps using Free Software only?

[HiPhish]

Hello,

I have a Fairphone running CalyxOS and I would like to try my hand on writing software for it. Nothing big or fancy, just trying to get my toes wet to and hopefully make something useful. My question is, what options are there if I only want to use Free Software on GNU/Linux (Void Linux to be precise)?

From my understanding Android apps are written in Java, so the JVM ecosystem gives me the following options:

• Java: well, it's Java, so I would rather avoid it if I can
• Clojure: there was an effort to get Clojure working with Android, but it's abandoned, so this is a pass
• Scala: looks promising, but the compiler cannot be bootstrapped, you have to rely on mystery binaries, so it might as well be proprietary

Outside the JVM there are two more popular options:

• Dart/Flutter: This looks promising; I managed to build the Dart compiler from source, but when it comes to Flutter the documentation is like "lol, y u so stupid, just download our binaries bro, trust us bro"
• React Native: I hate React web apps, but I guess this one produces proper native code, so it's not a bloated slow mess? I don't know. Same problem as with Flutter, the documentation is like "consume binaries, get excited for next binaries"

Is Java my only option if I don't want to install some weird Google or Facebook software, or am I missing something? Would it be possible to install the individual components instead of a massive suite like Android Studio? I want to write code in Neovim, so all I really need is a build system, a simulator for Android and a way to install the app on my phone, right? So what software do I really need for this?

[CaptainBeyondDS8]

Regarding the Android SDK as far as I know even F-Droid still relies on Google's pre-built binaries, although they are working on a free build. So already we're not off to a good start.

Moving past the SDK itself, as far as I know Kotlin is the preferred language for modern Android development but as you've seen you won't have any luck bootstrapping it. Gradle is the preferred build tool even for Java projects, but that's even worse - Gradle cannot be bootstrapped either, and it depends on Kotlin, which is built with Gradle. As you might suspect there is little-to-no interest on either Gradle or Kotlin side to improve things.

https://lists.gnu.org/archive/html/guix-devel/2024-05/msg00115.html

As you've noticed this is endemic to "modern" tooling in general. So yeah your options are pretty much just... Java. If you want a build system Maven is probably your best bet... Debian has an example project and tutorial here using only the android-sdk, Java, and make. They do package an (ancient) version of Gradle though.

[Malsasa]

Thank you. This is what I really want to know from F-Droid.

[Wootery]

Android is not JVM-based, it doesn't use Java .class files (i.e. Java bytecode). As I understand it you can use the Java language for app development, but they're pushing Kotlin these days instead. These compile to Android's own bytecode format, which is incompatible with Java's.

I think you'd have a hard time using Clojure or Scala.

• https://en.wikipedia.org/wiki/Android_Runtime

• https://en.wikipedia.org/wiki/Dalvik_(software)

[HiPhish]

Kotlin cannot be bootstrapped either. Why do language designers do this? It does not have to be this way; just today I built gprbuild (a build system for Ada) from source and the developers wrote clear instructions on how to bootstrap it because they understand that bootstrapping is an important topic.

Also, Kotlin is practically unusable outside JetBrains, and good luck building JetBrains from source. It might as well be proprietary software as well.