androidx - what is the replacement for lifeCycler-extensions

Question

In a android library it is using

Implementation("androidx.lifecycle:lifecycle-extensions:2.2.0") {
        exclude group: "android.arch.lifecycle", module: "runtime"
    }

this is the usage:

// in library:
class AppLifecycleObserver implements LifecycleObserver {

    protected Context mAppContext;
    protected Callback mCb;

    AppLifecycleObserver(@NonNull Context appContext, @NonNull Callback cb) {
        mAppContext = appContext;
        mCb = cb;
    }

    public void register() {
        ProcessLifecycleOwner.get().getLifecycle().addObserver(this);
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_START)
    public void onStart() {
        mCb.doSomething();
    }
}

// in the app who uses this library will call the AppLifecycleObserver::register():
        mLifecycleObserver = new AppLifecycleObserver(context, callback);
        mLifecycleObserver.register();

question 1: it is said

The APIs in lifecycle-extensions have been deprecated. Instead, add dependencies for the specific Lifecycle artifacts you need.

what is the replacement for lifecycle-extensions?

question 2: lifecycle release note that Behavior Changes:

LifecycleRegistry now verifies that its methods are called on main thread. It was always a requirement for lifecycles of activities, fragments etc. An addition of observers from non-main threads resulted in hard to catch crashes in runtime. 

The ProcessLifecycleOwner.get().getLifecycle().addObserver(this) will cause rash if not running in main thread. How to allow the call in any thread but not crash (dont know how the library user app will make the call in what thread)? Note: we dont own a LifecycleRegistry here.

question from:https://stackoverflow.com/questions/65850618/what-is-the-replacement-for-lifecycler-extensions

Answer 1

seems this works:

1. lifecycle-process
2. just check and make sure it runs in main thread:

if (Thread.currentThread() != Looper.getMainLooper().getThread()) {
   Handler mainLoopHandler = new Handler(Looper.getMainLooper());
   Runnable myRunnable = new Runnable() {
            @Override
            public void run() {
                getLifeCycle().addObserver(AppLifecycleObserver.this);
            }
        };
        mainLoopHandler.post(myRunnable);
}