How to detect when an Android app goes to the background and come back to the foreground

Question

I am trying to write an app that does something specific when it is brought back to the foreground after some amount of time. Is there a way to detect when an app is sent to

Answer 1

Correct Answer here

Create class with name MyApp like below:

public class MyApp implements Application.ActivityLifecycleCallbacks, ComponentCallbacks2 {

    private Context context;
    public void setContext(Context context)
    {
        this.context = context;
    }

    private boolean isInBackground = false;

    @Override
    public void onTrimMemory(final int level) {
        if (level == ComponentCallbacks2.TRIM_MEMORY_UI_HIDDEN) {


            isInBackground = true;
            Log.d("status = ","we are out");
        }
    }


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

    }

    @Override
    public void onActivityStarted(Activity activity) {

    }

    @Override
    public void onActivityResumed(Activity activity) {

        if(isInBackground){

            isInBackground = false;
            Log.d("status = ","we are in");
        }

    }

    @Override
    public void onActivityPaused(Activity activity) {

    }

    @Override
    public void onActivityStopped(Activity activity) {

    }

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

    }

    @Override
    public void onActivityDestroyed(Activity activity) {

    }

    @Override
    public void onConfigurationChanged(Configuration configuration) {

    }

    @Override
    public void onLowMemory() {

    }
}

Then, everywhere you want (better first activity launched in app), add the code below:

MyApp myApp = new MyApp();
registerComponentCallbacks(myApp);
getApplication().registerActivityLifecycleCallbacks(myApp);

Done! Now when the app is in the background, we get log status : we are out and when we go in app, we get log status : we are out