Android - Use the Activity callback in a standard java class

Issue

I'm developing an .aar library and I really need to interact with the lifecycle of an activity (so the callback onCreate(), on onResume(), etc...) in a standard java class. I tried a lot of things but nothing works. Is there a way I can do that?

Solution

From my understanding you need some thing like this,

import android.app.Activity;
import android.app.Application;
import android.os.Bundle;

/**
 * @Krish
 */

public class LifeCycleObserver {

    private LifeCycleObserver() {}

    private static LifeCycleObserver sLifeCycleObserver;

    public static LifeCycleObserver getInstance()
    {
        if (sLifeCycleObserver == null)
        {
            sLifeCycleObserver = new LifeCycleObserver();
        }

        return sLifeCycleObserver;
    }


    public static void init(Application application)
    {
        application.registerActivityLifecycleCallbacks(sLifeCycleObserver.lifecycleCallbacks);
    }


    private Application.ActivityLifecycleCallbacks lifecycleCallbacks = new Application.ActivityLifecycleCallbacks() {

        @Override
        public void onActivityCreated(Activity activity, Bundle savedInstanceState) {

        }

        @Override
        public void onActivityStarted(Activity activity) {

        }

        @Override
        public void onActivityResumed(Activity activity) {

        }

        @Override
        public void onActivityPaused(Activity activity) {

        }

        @Override
        public void onActivityStopped(Activity activity) {

        }

        @Override
        public void onActivitySaveInstanceState(Activity activity, Bundle outState) {

        }

        @Override
        public void onActivityDestroyed(Activity activity) {

        }
    };

}

and use it like this in Application class,

import android.app.Application;

/**
 * Created by krish
 */

public class MyApplication extends Application {

    @Override
    public void onCreate() {
        super.onCreate();
        LifeCycleObserver.init(this);
    }
}

Answered By - Krish