I have question about generic types, subtypes and mismatching between those. I have specific structure classes and interface. I'll show you and please explain me why the type mismatch occurs.
Let's say I'm preparing my MVP framework and I have following interfaces and classes:
This is highest abstraction
interface Presenter<in V : AbstractView> {
fun attachView(view: V)
fun detachView()
fun onDestory() {
}
}
The abstract class contains specific methods and implementation of Presenter
abstract class AbstractPresenter<V : AbstractView> : Presenter<V>, LifecycleObserver {
private var viewReference: WeakReference<V?>? = null
protected abstract fun onAttached(view: V)
final override fun attachView(view: V) {
viewReference = WeakReference(view)
onAttached(view)
}
final override fun detachView() {
viewReference?.clear()
viewReference = null
onDetached()
}
protected open fun onDetached() {
}
}
Contract
interface DashboardContract {
interface View : AbstractView {
}
abstract class Presenter : AbstractPresenter<View>(){
}
}
and finally
class DashboardPresenter : DashboardContract.Presenter() {
override fun onAttached(view: DashboardContract.View) {
}
}
In terms of AbstractView it looks simpler. There is just interface AbstractView. In contract DashboardContract.View extends AbstractView interface and my DashboardActivity implement this DashboardContract.View interface.
class DashboardActivity : BaseActivity(), DashboardContract.View { ... }
So when I create DashboardPresenter as a property in my DashboardActivity and create method fun getPresenter() : Presenter<AbstractView> then I got Type mismatch error Why? isn't a subtype of Presenter<AbstractView>?
fun getPresenter() : AbstractPresenter<AbstractView> {
return dashboardPresenter // The type is DashboardPresenter
}
Let's take a looka at the Java code:
I'm watching the Java code from decompile Kotlin. I put it below. This is how the Presenter looks like:
public interface Presenter {
void attachView(#NotNull AbstractView var1);
void detachView();
void onDestory();
#Metadata(...)
public static final class DefaultImpls {
public static void onDestory(Presenter $this) {
}
}
}
I thought that If I use generic class in Kotlin I get the generic class in java too. I was wrong.
The AbstractPresenter gives:
public abstract class AbstractPresenter implements Presenter, LifecycleObserver {
private WeakReference viewReference;
protected abstract void onAttached(#NotNull AbstractView var1);
public final void attachView(#NotNull AbstractView view) {
Intrinsics.checkParameterIsNotNull(view, "view");
this.viewReference = new WeakReference(view);
this.onAttached(view);
}
public final void detachView() {
WeakReference var10000 = this.viewReference;
if(this.viewReference != null) {
var10000.clear();
}
this.viewReference = (WeakReference)null;
this.onDetached();
}
protected void onDetached() {
}
public void onDestory() {
DefaultImpls.onDestory(this);
}
}
Contract
public interface DashboardContract {
#Metadata(...)
public interface View extends AbstractView {
}
#Metadata(...)
public abstract static class Presenter extends AbstractPresenter {
}
}
The DashboardPresetner:
public final class DashboardPresenter extends Presenter {
protected void onAttached(#NotNull View view) {
Intrinsics.checkParameterIsNotNull(view, "view");
}
// $FF: synthetic method
// $FF: bridge method
public void onAttached(AbstractView var1) {
this.onAttached((View)var1);
}
}
You have to change the parent of Presenter in DashboardContractto use AbstractView instead of View:
abstract class Presenter : AbstractPresenter<AbstractView>()
I'm not sure why you're not allowed to use View instead, this might be a flaw
in the recursive type checking of Kotlin. It might be interesting to see what the corresponding java code is and continue investigating from that.
Related
I know it was asked before, but i am currently diving into testing and i have the struggle to unit test presenter in MVP pattern with Mockito
My code setup:
Item class
public class ItemJSON {
#SerializedName("title")
String textHolder;
#SerializedName("id")
int factNumber;
public ItemJSON(String factText, int factNumber) {
this.textHolder = factText;
this.factNumber = factNumber;
}
//getters and setters
}
Contractor:
public interface Contractor {
interface Presenter {
void getPosts();
}
interface View {
//parse data to recyclerview on Succesfull call.
void parseDataToRecyclerView(List<ItemJSON> listCall);
void onResponseFailure(Throwable throwable);
}
interface Interactor {
interface onGetPostsListener {
void onSuccessGetPostCall(List<ItemJSON> listCall);
void onFailure(Throwable t);
}
void getPosts(onGetPostsListener onGetPostsListener);
}
}
API class:
#GET("posts")
Call<List<ItemJSON>> getPost();
Interactor class:
public class InteractorImpl implements Contractor.Interactor{
#Override
public void getPosts(onGetPostsListener onGetPostsListener) {
// NetworkService responsible for seting up Retrofit2
NetworkService.getInstance().getJSONApi().getPost().enqueue(new Callback<List<ItemJSON>> () {
#Override
public void onResponse(#NonNull Call<List<ItemJSON>> call, #NonNull Response<List<ItemJSON>> response) {
Log.d("OPERATION #GET","CALLBACK SUCCESSFUL");
onGetPostsListener.onSuccessGetPostCall (response.body ());
}
#Override
public void onFailure(#NonNull Call<List<ItemJSON>>call, #NonNull Throwable t) {
Log.d("OPERATION #GET","CALLBACK FAILURE");
onGetPostsListener.onFailure (t);
}
});
}
Presenter class:
public class PresenterImpl implements Contractor.Presenter, Contractor.Interactor.onGetPostsListener {
private final Contractor.View view;
private final Contractor.Interactor interactor;
public PresenterImpl (Contractor.View view,Contractor.Interactor interactor){
this.view = view;
this.interactor = interactor;
}
#Override
public void getPosts() {
interactor.getPosts (this);
}
#Override
public void onSuccessGetPostCall(List<ItemJSON> listCall) {
view.parseDataToRecyclerView (listCall);
}
}
So i try to ran some unit test on presenter, but they constanlty fail and i keep getting next error
Wanted but not invoked Actually, there were zero interactions with this mock
Unit test class:
#RunWith (MockitoJUnitRunner.class)
public class ApiMockTest{
#Mock
Contractor.View view;
private PresenterImpl presenter;
#Captor
ArgumentCaptor<List<ItemJSON>> jsons;
#Before
public void setUp() {
MockitoAnnotations.openMocks (this);
presenter = new PresenterImpl (view,new InteractorImpl ());
}
#Test
public void loadPost() {
presenter.getPosts ();
verify(view).parseDataToRecyclerView (jsons.capture ());
Assert.assertEquals (2, jsons.capture ().size ());
}
}
I try to understand what i am doing wrong and how to fix this issue, but as for now i am ran out of ideas. I will aprecciate any help.
Thanks in the adavance
UPD: in all cases in main activity presenter get called in onClick
Main Activity class:
public class MainActivity extends AppCompatActivity implements Contractor.View {
public Contractor.Presenter presenter;
#Override
protected void onCreate(Bundle savedInstanceState) {
presenter = new PresenterImpl (this,new InteractorImpl ());
binding.getButton.setOnClickListener(view ->presenter.getPosts () );
...//code
#Override
public void parseDataToRecyclerView(List<ItemJSON> listCall) {
adapter.updateList(listCall); //diff call to put data into recyclerview adapter
}
}
}
I ran into this situation also, even using the mockk library. The problem is that your method is an interface method. You need to actually call it from a view which has implemented this interface.
I have ViewModel
class MyViewModel extends BaseViewModel{
public void foo(){
// some code or return some boolean
}
}
View Class
class MyView extends View{
private MyViewModel myviewmodel;
public void bindTo(MyViewModel viewModel) {
this.viewModel = viewModel;
context = viewModel.getContext();
validateView();
requestLayout();
}
private validateView(){
//some code
}
}
this bind view method bind with adapter
I want to get call back in Myview class when ever i will validateView will call please suggest me how get call back from Viewmodel method to View in android.
it is best practice to use live data for communicating from viewmodel to your view.
class MyViewModel {
private MutableLiveData<Boolean> state = new MutableLiveData<Boolean>;
public LiveData<Boolean> getState() {
return state;
}
public void foo() {
//bool = value returned of your work
state.setValue(bool);
} }
class Myview extends View {
public void onCreate() {
viewmodel.getState().observe(this, observer); // 'this' is life cycle owner
}
final Observer<Boolean> observer = new Observer<Boolean>() {
#Override
public void onChanged(#Nullable final Boolean state) {
// do your work with returned value
}
}; }
for more details refer to this
Correct Me if i wrong
first you need to make interface class
public interface ViewModelCallback {
void returnCallBack(Boolean mBoolean);
}
then your View class implements that interface class & Override that method
class MyView extends View implements ViewModelCallback
#Override
public void returnCallBack(Boolean mBoolean) {
//here you will retrieve callback
// Do Something
}
Next you just pass a value from your view model
class MyViewModel {
private ViewModelCallback myViewCallBack;
public void foo() {
Boolean yourReturnValue = false;
myViewCallBack.returnCallBack(yourReturnValue);
}
}
I am trying to make an injection using Dagger 2, but it always returns null. I think I am doing all right, but anyway it does not work.
Here is the application class:
public class ApplicationSA extends Application {
private static AppComponent appComponent;
#Override
public void onCreate() {
super.onCreate();
appComponent = DaggerAppComponent.create();
}
public static AppComponent getComponent() {
return appComponent;
}
}
The component interface:
#Component(modules = {
SnoreDetectorClass.class,
AudioRecorderClass.class
})
public interface AppComponent {
void injectsMainFunctionalityActivity(Activity activity);
}
An the main class where I am trying to get the object:
public class MainFunctionalityActivity extends AppCompatActivity {
#Inject
AudioRecorderClass audioRecorderClass;
#Inject
SnoreDetectorClass snoreDetectorClass;
#Override
protected void onCreate(Bundle savedInstanceState) {
ApplicationSA.getComponent().injectsMainFunctionalityActivity(this);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.d("TESTING","audioRecorderClass= "+audioRecorderClass); // always null
Log.d("TESTING","snoreDetectorClass= "+snoreDetectorClass); // always null
...
}
And here are the module classes:
#Module
public class AudioRecorderClass {
public interface AudioRecorderInterface {
void AudioRecorder_hasUpdate(double amplitude_in_dB);
}
public AudioRecorderInterface delegate = null;
#Provides
AudioRecorderClass provideAudioRecorderClass(Activity activity) {
delegate = (AudioRecorderInterface)activity;
return new AudioRecorderClass();
}
...
#Module
public class SnoreDetectorClass {
#Provides
SnoreDetectorClass provideSnoreDetectorClass() {
return new SnoreDetectorClass();
}
...
What am I doing wrong ? Why the objects are always null ?
Ah, I see what is going on here. You cannot inject into a subclass. So in your AppComponent you cannot have
void injectsMainFunctionalityActivity(Activity activity);
you must inject with
void injectsMainFunctionalityActivity(MainFunctionalityActivity activity);
As a side note I would suggest not combining your injector and your model class. Better to have separation of concerns. Keep them separate
You have to specifically tell dagger which activity will be injected here, not use the super class Activity but rather your own implementation of the Activity class :
void injectsMainFunctionalityActivity(Activity activity);
change to:
void injectsMainFunctionalityActivity(MainFunctionalityActivity activity);
I am trying MVP pattern with TDD.
I have the following contract for Model, View And Presenter
Contract Class
interface GithubContract {
interface View {
void displayUsers(List<GurkhaComboDTO> userList);
}
interface Model {
void getUsersAndPromptPresenter(String userName, Presenter presenter);
}
interface Presenter {
void searchUsers(String userName);
void loadUsers(List<GithubUserDTO> userList);
}
}
I am trying to unit test the presenter logic like this :
Test Class
#RunWith(MockitoJUnitRunner.class)
public class GithubPresenterWithMockitoTest {
#Mock
GithubContract.Model mockedModel;
#Test
public void shouldDisplayUsersToScreen() {
//given
final GithubContract.View view = new MockView(); // I have created the mock myself for the view this time.
final GithubContract.Presenter presenter = new GithubPresenter(view, mockedModel);
***********************************************************
// I do not know what to write here
****************************************************
presenter.searchUsers("");
Assert.assertEquals(true, ((MockView) (view)).enoughItems);
}
}
My MockView / VIEW class looks like this :
This is -> Mock class
class MockView implements GithubContract.View {
boolean enoughItems = false;
#Override
public void displayUsers(List<GurkhaComboDTO> userList) {
enoughItems = true;
}
}
My PRESENTER implementation of contract is like this ..
This is -> Real Class
class GithubPresenter implements GithubContract.Presenter {
private GithubContract.View view;
private GithubContract.Model model;
GithubPresenter(GithubContract.View view, GithubContract.Model model) {
this.view = view;
this.model = model;
}
#Override
public void searchUsers(String userName) {
model.getUsersAndPromptPresenter(userName, this);
}
#Override
public void loadUsers(List<GithubUserDTO> data) {
if (data != null) {
if (!data.isEmpty()) {
view.displayUsers(users);
}
}
}
I have the MODEL class Implementation like this :
This is -> Real Class
public class GithubModel implements Model {
#Inject
GithubAPIService apiService;
private Call<GithubUserListDTO> userListCall;
private Context context;
GithubModel(Context context) {
this.context = context;
apiService = Util.getAPIService(); // I am using dagger, retrofit and okhttp3 with GSON to get Objects directly from network call
}
#Override
public void getUsersAndPromptPresenter(final String userName, final GithubContract.Presenter presenter) {
userListCall = apiService.searchGitHubUsers(userName);
if(Util.isInternetConnected(context)) {
userListCall.enqueue(new Callback<GithubUserListDTO>() {
#Override
public void onResponse(Call<GithubUserListDTO> call, Response<GithubUserListDTO> response) {
try {
presenter.loadUsers(response.body().getList());
} catch (Exception ignored) {
Util.log(ignored.getMessage());
}
}
#Override
public void onFailure(Call<GithubUserListDTO> call, Throwable t) {
}
});
}else {
Util.log("No Internet");
}
}
}
Now the real problem part:
I was successfully able to test the presenter with the mock of GithubContract.Model myself, But I want to use Mockito to mock the Model but as my getUsersAndPromptPresenter() method is abstract, returns void, takes parameters and calls back to presenter from an Inner class inside the method.
How can I mock my Model? If I need to bring some change in architecture in order to be able to make it testable, then please suggest it.
You shouldn't pass presenter to Model, Model and Presenter shouldn't be tightly coupled because it prevents model classes from being reusable. Instead provide succesfull and error callbacks(or a composite object that contains both these callbacks). And then you will be able to capture that callback with mockito and call the required one. Also it's very common today to use RxJava, it makes it easier to mock Model classes.
And here is a general good practice: you should avoid to use And/Or words in method names because it indicates that the method is doing more than one thing which is bad
I want to be able to inject an object, and pass a parameter to its initializer method.
Is this possible?
public class MyObject
{
#Inject
public MyObject(int anInteger)
{
//do something
}
}
public class MyActivity extends RoboActivity
{
#Inject (anInteger = 5) MyObject myObject;
// I want to be able to pass an object to be used when calling the
// initializer method
}
You should be able to do it with bindConstant() and annotating it accordingly. See, for example, How do I inject configuration parameters?
public class MyModule extends AbstractModule
{
#Override
protected void configure()
{
bind(Integer.class).
annotatedWith(Names.named("my.object.an.integer")).
toInstance(500);
}
#Provides
#Named("an.integer.5")
public MyObject myObject5()
{
return createMyObject(5);
}
#Provides
#Named("an.integer.100")
public MyObject providesMyObject100()
{
return createMyObject(100);
}
private MyObject createMyObject(int anInteger)
{
MyObject result = new MyObject(anInteger);
// if there are any other fields/setters annotated with #Inject
requestInjection(result);
return result;
}
}
public class MyObject
{
public MyObject(int anInteger)
{
System.out.println("anInteger = " + anInteger);
}
}
public class User
{
#Inject
#Named("an.integer.5")
private field MyObject five;
#Inject
#Named("an.integer.100")
private field MyObject hundred;
}