Feedback about the feedback #1

wojtekno · 2020-07-20T11:21:56Z

I got feedback from the reviewer, but

I'm not sure how to understand some of it,
not sure if I implemented the changes correctly

Remove Location from viewModel

wojtekno · 2020-07-20T11:23:40Z

That's the feedback I got.
it is written to the subbmited_solution state of code.
The post below I've highlighted a few points most relevant for me.

Application works and looks fine, but doesn't have a wow effect.
The project meets most of the expectations. The functionalities are here; however, there's little Kotlin code, no tests, and no architecture.
Most of the tasks which could block the main thread works on background thread.
The project structure is ok, but configuration could be more optimized. There's no tool used to help separate concerns.
There is no mess in the project, but there are some places which could be cleaned/improved before submitting the solution. Many lines of code can be simplified.
Most views don't have the logic inside, they are readable, with some exceptions. Business logic is coupled to Android SDK classes.
You write good Java code, but some parts could be implemented in more efficient way.
I assume that you found Event class on the web, perhaps in this article: https://medium.com/androiddevelopers/livedata-with-snackbar-navigation-and-other-events-the-singleliveevent-case-ac2622673150
I would like to see how you write Kotlin code instead.
You know most of basic Android SDK things, use Android components properly, but some things could be organized in more efficient way.
Almost all XMLs are well structured. Layouts are mostly well defined and reusable.
The project doesn't contain any tests.
The project contains common libraries, however some of the SDK classes or external libraries could be replaced with better ones. Unfortunately you didn't use any library from our stack.
In MainFragment, you have such code:
if (someBool) { someField = true } else { someField = false }
It’s clearer to just someField = someBool.
You tend to use getContext() which may lead to NullPointerException. The requireContext() method would provide a better insight into what happened in such case.
There are multiple constructs where inside some LiveData observer you have a single-branched conditional instruction. This code would greatly benefit from filter() method known from libraries like RxJava.
You implement SensorEventListener in MainFragment which couples code.
There’s no clear separation of architecture layer. You made a domain package, but inside are Android SDK dependencies.
You use ViewModel where most of the logic dwells, but it’s strongly coupled to Android Data Binding, so I can’t take it as an MVVM.

wojtekno · 2020-07-22T11:51:25Z

I have a problem with a proper understanding of these below four points.
I implemented some solutions, but I would like to make sure and understand better what I did wrong the first attempt.

Business logic is coupled to Android SDK classes.
The project contains common libraries, however some of the SDK classes or external libraries could be replaced with better ones.
There’s no clear separation of architecture layer. You made a domain package, but inside are Android SDK dependencies.
You use ViewModel where most of the logic dwells, but it’s strongly coupled to Android Data Binding, so I can’t take it as an MVVM.

wojtekno · 2020-07-22T11:55:37Z

app/src/main/java/com/nowak/wjw/simplecompass/data/location/LocationApiHandler.java

 import timber.log.Timber;

+//todo There’s no clear separation of architecture layer. You made a `domain` package, but inside are Android SDK dependencies.
 public class LocationApiHandler extends LocationCallback {


I use this class as my data source. Is it OK from the architecture point of view?

wojtekno · 2020-07-22T11:59:46Z

app/src/main/java/com/nowak/wjw/simplecompass/domain/GetDestinationBearingUseCase.java

@@ -0,0 +1,43 @@
+package com.nowak.wjw.simplecompass.domain;
+
+import android.location.Location;


Reviewer comment - "There’s no clear separation of architecture layer. You made a domain package, but inside are Android SDK dependencies."
I don't understand why Location cannot be here.
I need to take it and process it.

I can understand that it shouldn't be in viewModel or fragment,- but here? - why not?

Osoba która robiła ci review zwraca ci uwagę na to że warstwa domeny posiada zależności stricte z androida.
Generalnie z tego co widzę to próbujesz użyć wszystkiego na co zwrócisz uwagę na internecie, a brakuję ci wiedzy i doświadczenia żeby to wszystko spiąć w logiczną całość. Nawet radziłbym używać mniej złożonej architektury a starać się oddzielić warstwę prezentacji,danych i logiki.

wojtekno · 2020-07-22T12:02:12Z

app/src/main/java/com/nowak/wjw/simplecompass/ui/main/CompassStateEnum.java

-package com.nowak.wjw.simplecompass;
+package com.nowak.wjw.simplecompass.ui.main;

 public enum CompassStateEnum {


where is the place for that enum? what package?

wojtekno · 2020-07-22T12:04:59Z

app/src/main/java/com/nowak/wjw/simplecompass/ui/main/MainFragment.java

    private ActivityResultLauncher<String> requestPermissionLauncher =
            registerForActivityResult(new ActivityResultContracts.RequestPermission(), isGranted -> {


Is this the right place for that launcher? Please confirm or explain otherwise.

wojtekno · 2020-07-22T12:07:11Z

app/src/main/java/com/nowak/wjw/simplecompass/ui/main/MainFragment.java

+        mViewModel.needScreenOrientation.observe(getViewLifecycleOwner(), isNeeded -> {
+            if (isNeeded) {
+                int mScreenRotation = requireActivity().getWindowManager().getDefaultDisplay().getRotation();
+                mViewModel.provideScreenRotation(mScreenRotation);


what would be a better way to do this?
putting it inside onResume didn't work cause when you flip your phone by 180degrees there is no onCreate triggered.

wojtekno · 2020-07-22T12:10:36Z

app/src/main/java/com/nowak/wjw/simplecompass/ui/main/MainFragment.java

-                isRequestingLocationUpdates = true;
-                if (!foundLastLocation) configureLocation();
-                findButtonClicked();
+                btnClickAllowed();


I would like to deal with the buttonClicked directly in ViewModel, but I cannot figure out how to do that.
VM registers the click and need to check if permission granted.
If yes that's awesome, easy.
But if not, he needs to notify fragment about that ,and later if permission granted, the vm.buttonClicked has to be called once again with appropriate params - I don't know how to handle it

wojtekno · 2020-07-22T12:11:32Z

app/src/main/java/com/nowak/wjw/simplecompass/ui/main/MainViewModel.java

+import com.nowak.wjw.simplecompass.domain.StartStopSensorListenerUseCase;

 import timber.log.Timber;



Reviewers comment - "You use ViewModel where most of the logic dwells, but it’s strongly coupled to Android Data Binding, so I can’t take it as an MVVM."

I don't understand that

holakmateusz · 2020-07-22T14:38:38Z

app/src/main/java/com/nowak/wjw/simplecompass/Event.kt

@@ -1,24 +0,0 @@
-package com.nowak.wjw.simplecompass
-
-open class Event<out T>(private val content: T) {


Pisałeś sam tę klasę czy skądś brałeś ? Czemu nie piszesz w kotlinie tak w ogóle ?

https://medium.com/androiddevelopers/livedata-with-snackbar-navigation-and-other-events-the-singleliveevent-case-ac2622673150
stwierdziłem, że opanuje pewne rzeczy najpierw w Javie (javaRx, dagger itp) a później będę się uczył kotlina.
Ale zaczłąem już się uczyć, bo po ogłoszeniach na pracę, widze , że bez kotlina to ciężko

holakmateusz · 2020-07-23T14:40:14Z

chcesz teraz pogadać ? czw., 23 lip 2020 o 16:36 Wojtek (Voytech) <[email protected]> napisał(a):

…

***@***.**** commented on this pull request. ------------------------------ In app/src/main/java/com/nowak/wjw/simplecompass/Event.kt <#1 (comment)>: > @@ -1,24 +0,0 @@ -package com.nowak.wjw.simplecompass - -open class Event<out T>(private val content: T) { https://medium.com/androiddevelopers/livedata-with-snackbar-navigation-and-other-events-the-singleliveevent-case-ac2622673150 stwierdziłem, że opanuje pewne rzeczy najpierw w Javie (javaRx, dagger itp) a później będę się uczył kotlina. Ale zaczłąem już się uczyć, bo po ogłoszeniach na pracę, widze , że bez kotlina to ciężko — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#1 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AEN2TVKQMANMZIDBCZKLEGLR5BDITANCNFSM4PCGJ2JA> .

-- *Holak Mateusz*

holakmateusz

zrobiłem ci review

app/src/main/java/com/nowak/wjw/simplecompass/data/Compass.java

holakmateusz · 2020-07-31T17:00:32Z

app/src/main/java/com/nowak/wjw/simplecompass/data/Compass.java

+        // calculate th rotation matrix
+        SensorManager.getRotationMatrixFromVector(rMat, event.values);
+        int lAzimuth = (int) (Math.toDegrees(SensorManager.getOrientation(rMat, orientation)[0]) + 360) % 360;
+        return lAzimuth;


return w 1 linii

app/src/main/java/com/nowak/wjw/simplecompass/data/LocationCoordinates.kt

app/src/main/java/com/nowak/wjw/simplecompass/data/location/LocationApiHandler.java

app/src/main/java/com/nowak/wjw/simplecompass/ui/main/MainFragment.java

holakmateusz · 2020-07-31T17:33:41Z

app/src/main/java/com/nowak/wjw/simplecompass/ui/main/MainViewModel.java

    public LiveData<Boolean> hideKeyBoard;
+    public LiveData<Boolean> showLocationError;
+    private MutableLiveData<Boolean> mShouldProvideRationale = new MutableLiveData<>(false);
+    public LiveData<Event<Boolean>> shouldProvideRationale = Transformations.map(mShouldProvideRationale, should -> new Event(should));


pytasz, czy sugerujesz?
jak dla mnie to lambda jest ;P

można to uproscic

nie jest to dla mnie widoczne na pierwszy rzut oka, zastanowie sie i dam znać

chodzi mi o to że można zrobić odwołanie do elementu klasy, u ciebie by to było Event::new

holakmateusz · 2020-07-31T17:35:19Z

app/src/main/java/com/nowak/wjw/simplecompass/ui/main/MainViewModel.java

-    private MutableLiveData<Boolean> mStartLocationUpdates = new MutableLiveData<>(false);
+    private MutableLiveData<Integer> mScreenOrientation = new MutableLiveData<>(0);
+    private LiveData<Integer> mAzimuth;
+    private MutableLiveData<LocationCoordinates> mDestinationCoordinates = new MutableLiveData<>();


generalnie mam wrażenie że tego nie wiesz ale możę się mylę: mutableLiveData jest ukrywana po to żeby nikt z zewnątrz jej nie modyfikował - wystawiamy liveData jako immutableData które można obserwować. PRzez to że wszędzie używasz dataBinding używasz liveData co jest w sumie spoko.

intencjonalnie pola MutableLiveData są prywatne, a wszystko co udostępniam, udostępniam jako LiveDate - właśnie, żeby nie można było przy tym grzebać.

holakmateusz · 2020-07-31T17:36:18Z

app/src/main/java/com/nowak/wjw/simplecompass/ui/main/MainViewModel.java

+    public LiveData<Event<Boolean>> requestLocationPermission = Transformations.map(mRequestLocationPermission, request -> new Event<>(request));
+
+
+    public MainViewModel(GetAzimuthUseCase getAzimuthUseCase, StartStopSensorListenerUseCase startStopSensorListenerUseCase, InitiateLastLocationUseCase initiateLastLocationUseCase, RequestAndStopLocationUpdatesUseCase requestAndStopLocationUpdatesUseCase, GetDestinationBearingUseCase getDestinationBearingUseCase) {


ten konstruktor jest tragicznie długi, samo formatowanie jużby pomogło.

co do tego konstruktora to mam pytanie - czy inicjalizować te zmienne w konstruktorze, czy lepiej utworzyć metody które będą je ekspozycjonować, np

public LiveData getDestArrowRotation(){
return Transformations.switchMap(mDestinationBearing, b -> {
Timber.d("destArrowRotation");
if (b == null) return null;
return Transformations.map(needleRotation, r -> {
Timber.d("needleRotation");
return r + b;
});
});

tylko, że wtedy za każdym razem kiedy wywołany tę metodę to będziemy na nowo wywoływać ten kod, a tak to tylko raz go wywołujemy - plus Transformacje go wywołują, ale to i tak by się działo...

po to masz blok inicjalizujący init żeby takie startowe operacje wykonać w momencie użycia viewModelu.

holakmateusz

1 uwaga

holakmateusz · 2020-07-31T19:40:19Z

app/src/main/java/com/nowak/wjw/simplecompass/Event.kt

+class Event<out T>(private val content: T) {
+
+    var hasBeenHandled = false
+        private set // Allow external read but not write


property jako private i setter wtedy będzie zbędny

tak w ogole ta klasa dla mnie ma mały sens, funkcjonalnie ją rozumiem ale jest bez sensu napisana. JAk bym coś kopiowal to juz jakies dobre rozwiazania a nie jakis kod pisany na kolanie przez kogos.

no ja jeszcze nie do końca potrafie odróżnić jedno od drugiego LOL

holakmateusz · 2020-07-31T19:40:33Z

app/src/main/java/com/nowak/wjw/simplecompass/Event.kt

+        } else {
+            hasBeenHandled = true
+            content
+        }


when (hasBeenHandled) { true -> null false -> { hasBeenHandled = true content } }

wojtekno added 3 commits July 13, 2020 12:40

Decouple MainFragment from SensonrEventListener, create SensorHandler

5d096a4

Create GetAzimuthUseCase and Compass classes

0152a01

Create Location related useCases

fa5eb9a

Remove Location from viewModel

wojtekno commented Jul 22, 2020

View reviewed changes

holakmateusz reviewed Jul 22, 2020

View reviewed changes

wojtekno added 2 commits July 31, 2020 18:13

Remove permission logic from Fragment

1fe6392

Implement JavaRx in Compass

a9297f1

holakmateusz reviewed Jul 31, 2020

View reviewed changes

		@@ -0,0 +1,43 @@
		package com.nowak.wjw.simplecompass.domain;

		import android.location.Location;

		private ActivityResultLauncher<String> requestPermissionLauncher =
		registerForActivityResult(new ActivityResultContracts.RequestPermission(), isGranted -> {

		import com.nowak.wjw.simplecompass.domain.StartStopSensorListenerUseCase;

		import timber.log.Timber;

		@@ -1,24 +0,0 @@
		package com.nowak.wjw.simplecompass

		open class Event<out T>(private val content: T) {

		public LiveData<Event<Boolean>> requestLocationPermission = Transformations.map(mRequestLocationPermission, request -> new Event<>(request));


		public MainViewModel(GetAzimuthUseCase getAzimuthUseCase, StartStopSensorListenerUseCase startStopSensorListenerUseCase, InitiateLastLocationUseCase initiateLastLocationUseCase, RequestAndStopLocationUpdatesUseCase requestAndStopLocationUpdatesUseCase, GetDestinationBearingUseCase getDestinationBearingUseCase) {

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wojtekno commented Jul 20, 2020

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wojtekno commented Jul 22, 2020

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holakmateusz commented Jul 23, 2020 via email

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wojtekno commented Jul 20, 2020 •

edited

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