3.10.0-alpha4 breaks existing Android apps

[stephengold]

/mnt/virginia/home/sgold/NetBeansProjects/BasicGame-on-Droid/app/src/main/java/mygame/launcher/AndroidLauncher.java:3: error: cannot find symbol
import com.jme3.app.AndroidHarness;
                   ^
  symbol:   class AndroidHarness
  location: package com.jme3.app

The AndroidHarness class was removed from JME between 3.10.0-alpha3 and -alpha4. This breaks existing Android apps that were designed around AndroidHarness.

[riccardobl]

This was briefly discussed on discord and it is likely going to be a documented breaking change in 3.10, since it is part of the effort to modernize and upgrade our backends.

[stephengold]

What's the impediment to preserving backward compatibility?

[riccardobl]

The old android harness does a lot of questionable stuff (like forcing settings etc probably due to the fact that android was not a first a first class citizen in jme and it needed the engine configured in a certain way), and is full of legacy code.

Full backward compatibility would require to keep all those stuff in-place, with a lot of code duplication.

Partial backward compatibility, ie. keeping a AndroidHarness Activity that displays the new fragment fullscreen, is more feasible. But with the way AndroidHarness is designed, it seems to me the only good way to use it is to extend the class, and for that i doubt a partial backward compatibility would be enough.

The updated backend should make jme on android much easier and predictable, so probably worth the breaking change overall.

[stephengold]

What's the overall structure of a JME app on Android using the new back end?
Is there a tutorial that explains how to use the new back end?
An example app might help me get started. Do any open-source apps use the new back end?

[stephengold]

Are there plans to update the jMonkey initializer to make it compatible with JME v3.10.0?

[riccardobl]

Yeah, all that should happen before the beta release.
I have still some work left to do on the backends.
For now, the jme3-android-examples is a good, even if a bit confusing, demonstration of the way a the new harness can be used, but the gist is:

public class MyFragment extends AndroidHarnessFragment {   
    @Override
    protected LegacyApplication createApplication() throws Exception {
        return new MyJmeApplication();
    }
}

then it is just like any other android fragment

[stephengold]

Thank you

[nickidebruyn]

In terms of the AndroidHarness, I am intensely using it in my solution do deploy and build android apps.
Would there be a smoother transition to expect the same functionality and class in future releases of jMe?

[8Keep]

@riccardobl and I are aligned in this, I will try to bring back the old AndroidHarness API surface, but make it deprecated, so users can update to 3.10 and replace the deprecation post upgrade.

#2765

[richardTingle]

I love this approach. Means app states can be passed in to the constructor normally which wasn't possible with the reflection based initialisation