Develop Reference

Android Java Dagger Inject Problems

My AppComponent
#Singleton
#Component(modules = {SplashModule.class})
public interface AppComponent {
void inject(SplashActivity splashActivity);//this is inject activity
}
Splash Module
#Module
public class SplashModule {
#Provides
#Singleton
static SplashInteract provideSplashInteract(){
return new SplashInteract();//instance interact
};
#Provides
#Singleton
SplashPresenter provideSplashPresenter(SplashInteract splashInteract){
return new SplashPresenter(splashInteract);//instance SplashPresenter
};
}
Splash Presenter
public class SplashPresenter implements ISplashContract.Presenter {
ISplashContract.View mView;
SplashInteract splashInteract;
public SplashPresenter(SplashInteract splashInteract) {
this.splashInteract =splashInteract;
}
public void bindView(ISplashContract.View mView) {
this.mView = mView;
}
#Override
public void attach() {
this.mView.startAnimation();//start splash animation
}
#Override
public void start(Activity activity) {
this.splashInteract.SplashScreenAnimation(activity);// add interact methods
}
}
Splash Activity
public class SplashActivity extends AppCompatActivity implements ISplashContract.View{
#Inject SplashPresenter splashPresenter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_splash);
getAppComponent().inject(this);//call BaseApp DaggerAppComponent
splashPresenter.attach();
splashPresenter.bindView(this);
}
#Override
public void startAnimation() {
this.splashPresenter.start(this);
}
}
Base App
public class BaseApp extends Application {
private static AppComponent appComponent;
#Override
public void onCreate() {
super.onCreate();
setUp();
}
private void setUp() {
appComponent = DaggerAppComponent.builder().build();//Call Component in BaseApp
}
public static AppComponent getAppComponent() {
return appComponent;
}
}
Hi Everyone
I am writing a project, I want to use dagger, but I am inexperienced at this. This code gives a NullPointerException error. I could not find what I am doing wrong.
I need help and I will be glad if those who know better than the dagger guide me

In your case, dagger will not know how to provide splashPresenter, either do a constructor Injection or define in the module how SplashPresenter should be created, and remove SpashPresenter from the Component. The module approach should be like so,
#Module
public class SplashModule {
ISplashContract.View mView;
public SplashModule(ISplashContract.View mView) {
this.mView = mView;//add SplashModule view
}
#Provides
#Singleton
public ISplashContract.View provideSplashPresenter(){
return mView;//set this view
}
#Provides
static SplashInteract provideSplashInteract(){
return new SplashInteract();//instance interact
};
#Provides
SplashPresenter provideSplashPresenter(ISplashContract.View mView, SplashInteract splashInteract){
return new SplashPresenter(mView, splashInteract);//instance SplashPresenter
};
}
And remove inject annotations from SplashPresenter and you will also have to change the signature for its constructor. You can optionally remove Singleton annotation from the code, if the presenter is not supposed to be singleton.
Updates based on comments
public class SplashModule {
#Provides
static SplashInteract provideSplashInteract(){
return new SplashInteract();//instance interact
};
#Provides
SplashPresenter provideSplashPresenter(SplashInteract splashInteract){
return new SplashPresenter(splashInteract);//instance SplashPresenter
};
}
public class SplashPresenter implements ISplashContract.Presenter {
ISplashContract.View mView;
SplashInteract splashInteract;
public SplashPresenter(SplashInteract splashInteract) {
this.splashInteract = splashInteract;
}
public void bindView(ISplashContract.View mView) {
this.mView = mView;
}
#Override
public void attach() {
this.mView.startAnimation();//start splash animation
}
#Override
public void start(Activity activity) {
this.splashInteract.SplashScreenAnimation(activity);// add interact methods
}
}
public class SplashActivity extends AppCompatActivity implements ISplashContract.View{
#Inject SplashPresenter splashPresenter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_splash);
getAppComponent().inject(this);//call BaseApp DaggerAppComponent
splashPresenter.bind("the view you want to bind")
splashPresenter.attach();
}
#Override
public void startAnimation() {
this.splashPresenter.start(this);
}
}```

Make sure that you declare your BaseApp in AndroidManifest :
<application
android:name=".fullPathTo.BaseApp"
...

dagger2 field is not injected

I have an application (module + component) where
#Singleton
#Component(modules = AppModule.class)
public interface AppComponent {
void inject(App app);
Serializer getSerializer();
ListOfCallingLists getListOfCallingLists();
Context getContext();
App getApp();
}
And
#Module
public class AppModule {
private final App app;
public AppModule(App app) {
this.app = app;
}
#Provides
Serializer provideSerializer() {
return new BinarySerializer();
}
#Provides
Context provideContext() {
return app;
}
#Provides
App provideApp() {
return app;
}
}
And
#Singleton
public class ListOfCallingLists implements Serializable {
...
#Inject
public ListOfCallingLists(Context context,
Serializer serializer) {
this.serializer = serializer;
...
}
}
And App is the application, I registered it in manifest:
public class App extends Application {
private AppComponent appComponent;
public static App get(Context context) {
return (App) context.getApplicationContext();
}
#Override
public void onCreate() {
super.onCreate();
if (appComponent == null)
appComponent = DaggerAppComponent.builder()
.appModule(new AppModule(this))
.build();
appComponent.inject(this);
}
public AppComponent getComponent() {
return appComponent;
}
}
And finally the activity:
public class CallListsActivity extends AppCompatActivity {
#Inject
ListOfCallingLists list;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
...
}
#Override
public void onPostCreate(#Nullable Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// list here is null why?
}
}

In your AppComponent you need to add:
void inject(CallListsActivity callListActivity);
And in your CallListsActivity's onCreate() you need to tell how is your CallListsActivity injected.
For example, build your AppComponent and inject the activity, or you can use the new android injector: https://google.github.io/dagger/android.html

Android Dagger 2 and clean architecture implementation, scope errors

I'm trying to figure how to deal with dependency injection with dagger 2 and clean architecture in Android. What i want to achieve is when i click a button, a message will be saved to Firebase Database. And show success message to user. When i build my project i'm getting this error:
Error:(10, 1) error: com.example.mvpsample.home.HomeComponent
(unscoped) may not reference scoped bindings: #Provides #Singleton
com.google.firebase.database.FirebaseDatabase
com.example.mvpsample.data.DataModule.provideFirebaseDatabase()
Here my app class:
public class MyApp extends Application {
private static MyApp app;
private HomeComponent homeComponent;
private AuthenticationComponent authenticationComponent;
#Inject
Presenter presenter;
#Override
public void onCreate() {
super.onCreate();
app = this;
homeComponent = DaggerHomeComponent
.builder()
.homeModule(new HomeModule(presenter.getView()))
.build();
}
public HomeComponent getHomeComponent() {
return homeComponent;
}
public static MyApp app() {
return app;
}
}
HomeActivity
public class HomeActivity extends AppCompatActivity implements BaseContract.View {
#Inject
public Presenter presenter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ButterKnife.bind(this);
MyApp
.app()
.getHomeComponent()
.inject(this);
}
#OnClick(R.id.tvHello)
public void clickTvHello() {
presenter.writeStringToDatabase("Hi");
}
#Override
public void showSuccessMessage() {
Toast.makeText(this, "Success", Toast.LENGTH_SHORT).show();
}
}
HomeModule
#Module
public class HomeModule {
private final BaseContract.View View;
#Inject
public HomeModule(BaseContract.View View) {
this.View = View;
}
#Provides
public BaseContract.View provideView() {
return View;
}
}
HomeComponent
#Component(modules = {HomeModule.class, DataModule.class})
public interface HomeComponent {
void inject(HomeActivity homeActivity);
}
DataModule
#Module
public class DataModule {
#Provides
#Singleton
public FirebaseDatabase provideFirebaseDatabase() {
return FirebaseDatabase.getInstance();
}
}
BaseContract
public interface BaseContract {
interface View {
void showSuccessMessage();
}
interface Presenter {
View getView();
void writeStringToDatabase(String string);
}
}
Presenter
public class Presenter implements BaseContract.Presenter {
private final BaseContract.View View;
#Inject
FirebaseDatabase firebaseDatabase;
#Inject
public Presenter(BaseContract.View View) {
this.View = View;
}
#Override
public BaseContract.View getView() {
return View;
}
#Override
public void writeStringToDatabase(String string) {
firebaseDatabase.getReference()
.child("messages")
.push()
.child("value")
.setValue(string).addOnSuccessListener(new OnSuccessListener<Void>() {
#Override
public void onSuccess(Void aVoid) {
getView().showSuccessMessage();
}
});
}
}
I followed sample projects and tutorials but did not understand what i'm doing wrong here. Not looking for working project but i want to learn what is best practice of this and how to manage and use modules and components.

The problem is that your HomeComponent is not scoped while your DataModule provides a scoped dependency (i.e the FirebaseDatabase dependency).
A non-scoped component cannot rely on scoped provider. You either have to remove the #Singleton on your provideFirebaseDatabase() provider or add #Singleton on your HomeComponent.

Unit testing while using Dagger 2 (Robolectric and Mockito)

I'm trying to write some tests for fragments which have fields annotated with #Inject. For example, a chunk of my app looks like this:
Module:
#Module
public class PdfFactoryModule {
#Provides #Singleton
PdfFactory providePdfFactory() {
return PdfFactory.getPdfFactory();
}
}
Component:
#Singleton
#Component(modules = PdfFactoryModule.class)
public interface CorePdfComponent {
void inject(PagerFragment pagerFragment);
}
Application:
public class CorePdfApplication extends Application {
#NonNull
private CorePdfComponent component;
#Override
public void onCreate() {
super.onCreate();
component = DaggerCorePdfComponent.builder().build();
}
#NonNull
public CorePdfComponent getComponent() {
return component;
}
}
PagerFragment:
public class PagerFragment extends Fragment {
#Inject PdfFactory pdfFactory;
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Dagger 2
((CorePdfApplication) getActivity().getApplication()).getComponent().inject(this);
}
(Note that these are only snippets of my whole code, I'm showing only the essentials for this particular dependency to keep it clear.)
I was trying to do a test like this:
Fake Module:
#Module
public class FakePdfFactoryModule extends PdfFactoryModule {
#Override
PdfFactory providePdfFactory() {
return Mockito.mock(PdfFactory.class);
}
}
Fake Component:
#Singleton
#Component(modules = FakePdfFactoryModule.class)
public interface FakeCorePdfComponent extends CorePdfComponent {
void inject(PagerFragmentTest pagerFragmentTest);
}
Fake Application:
public class FakeCorePdfApplication extends CorePdfApplication {
#NonNull
private FakeCorePdfComponent component;
#Override
public void onCreate() {
super.onCreate();
component = DaggerFakeCorePdfComponent.builder().build();
}
#NonNull
public FakeCorePdfComponent getComponent() {
return component;
}
}
Test:
#RunWith(RobolectricTestRunner.class)
#Config(constants = BuildConfig.class, sdk = 21, application = FakeCorePdfApplication.class)
public class PagerFragmentTest {
PagerFragment pagerFragment;
#Before
public void setup() {
pagerFragment = new PagerFragment();
startVisibleFragment(pagerFragment);
}
#Test
public void exists() throws Exception {
assertNotNull(pagerFragment);
}
But the DaggerFakeCorePdfComponent doesn't generate. I may have messed up big time because I never tested with dependency injection. What am I doing wrong?

My advice - "Do not use dagger in tests".
Just change your code to next:
public class FakeCorePdfApplication extends CorePdfApplication {
#NonNull
private CorePdfComponent component = mock(CorePdfComponent.class);
#Override
public void onCreate() {
super.onCreate();
}
#NonNull
public CorePdfComponent getComponent() {
return component;
}
}
And:
#RunWith(RobolectricTestRunner.class)
#Config(constants = BuildConfig.class, sdk = 21, application = FakeCorePdfApplication.class)
public class PagerFragmentTest {
PagerFragment pagerFragment;
#Before
public void setup() {
pagerFragment = new PagerFragment();
CorePdfComponent component = ((CorePdfApplication)RuntimeEnvironment.application).getComponent();
doAnswer( new Answer() {
Object answer(InvocationOnMock invocation) {
fragment. pdfFactory = mock(PdfFactory.class);
return null;
}
}).when(component).inject(pageFragment);
startVisibleFragment(pagerFragment);
}
#Test
public void exists() throws Exception {
assertNotNull(pagerFragment);
}
}

You may try:
androidTestApt "com.google.dagger:dagger-compiler:<version>"
I was having similar problem, it worked for me.

Understanding Dagger 2 for Android development

Here's my code, which I based on some old tutorial found on the internet. There really should be some examples on the main site of Dagger 2, I found it really difficult to understand how to implement all this.
It's really a lot of work to get such a simple app to run. I have two questions:
Do I have to call DaggerLoggerComponent in every class I want to get some components like my Logger class?
Also how can I make the scope of the Logger class a singleton? Right now every button click creates a new logger instance.
Probably I dont understand some underlying concepts, I've only used dependency injection in Spring before and all of this seems strange to me.
public class MainActivity extends AppCompatActivity {
private Button button;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
init();
}
private void init(){
button = (Button)findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
LoggerComponent component = DaggerLoggerComponent.builder().loggerModule(new LoggerModule()).build();
component.getLogger().log("Hello!",MainActivity.this);
}
});
}
}
public class Logger {
private static int i = 0;
public Logger(){
i++;
}
public static int getI() {
return i;
}
public void log(String text, Context context){
Toast.makeText(context,text+" "+i,Toast.LENGTH_SHORT).show();
}
}
#Singleton
#Component(modules={LoggerModule.class})
public interface LoggerComponent {
Logger getLogger();
}
#Module
public class LoggerModule {
#Provides
#Singleton
Logger provideLogger(){
return new Logger();
}
}

The answer is
public class MainActivity extends AppCompatActivity {
#OnClick(R.id.button) //ButterKnife
public void onClickButton() {
logger.log("Hello!");
}
#Inject
Logger logger;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Injector.INSTANCE.getApplicationComponent().inject(this);
ButterKnife.bind(this);
}
#Override
protected void onDestroy() {
ButterKnife.unbind(this);
super.onDestroy();
}
}
public class Logger {
private static int i = 0;
private CustomApplication customApplication;
public Logger(CustomApplication application) {
this.customApplication = application;
i++;
}
public static int getI() {
return i;
}
public void log(String text){
Toast.makeText(customApplication, text + " " + i,Toast.LENGTH_SHORT).show();
}
}
public interface LoggerComponent {
Logger logger();
}
#Module
public class ApplicationModule {
private CustomApplication customApplication;
public ApplicationModule(CustomApplication customApplication) {
this.customApplication = customApplication;
}
#Provides
public CustomApplication customApplication() {
return customApplication;
}
}
#Module
public class LoggerModule {
#Provides
#Singleton
Logger provideLogger(){
return new Logger();
}
}
#Singleton
#Component(modules={LoggerModule.class, ApplicationModule.class})
public interface ApplicationComponent extends LoggerComponent {
CustomApplication customApplication();
void inject(MainActivity mainActivity);
}
public class CustomApplication extends Application {
#Override
public void onCreate() {
super.onCreate();
Injector.INSTANCE.initializeApplicationComponent(this);
}
}
public enum Injector {
INSTANCE;
private ApplicationComponent applicationComponent;
public ApplicationComponent getApplicationComponent() {
return applicationComponent;
}
void initializeApplicationComponent(CustomApplication customApplication) {
this.applicationComponent = DaggerApplicationComponent.builder()
.applicationModule(new ApplicationModule(customApplication))
.build();
}
}
This is currently our Dagger2 architecture.
EDIT: This is from our actual code for Retrofit stuff from our application we're making:
public interface RecordingService {
ScheduledRecordsXML getScheduledRecords(long userId)
throws ServerErrorException;
}
public class RecordingServiceImpl
implements RecordingService {
private static final String TAG = RecordingServiceImpl.class.getSimpleName();
private RetrofitRecordingService retrofitRecordingService;
public RecordingServiceImpl(RetrofitRecordingService retrofitRecordingService) {
this.retrofitRecordingService = retrofitRecordingService;
}
#Override
public ScheduledRecordsXML getScheduledRecords(long userId)
throws ServerErrorException {
try {
return retrofitRecordingService.getScheduledPrograms(String.valueOf(userId));
} catch(RetrofitError retrofitError) {
Log.e(TAG, "Error occurred in downloading XML file.", retrofitError);
throw new ServerErrorException(retrofitError);
}
}
}
#Module
public class NetworkClientModule {
#Provides
#Singleton
public OkHttpClient okHttpClient() {
OkHttpClient okHttpClient = new OkHttpClient();
okHttpClient.interceptors().add(new HeaderInterceptor());
return okHttpClient;
}
}
#Module(includes = {NetworkClientModule.class})
public class ServiceModule {
#Provides
#Singleton
public RecordingService recordingService(OkHttpClient okHttpClient, Persister persister, AppConfig appConfig) {
return new RecordingServiceImpl(
new RestAdapter.Builder().setEndpoint(appConfig.getServerEndpoint())
.setConverter(new SimpleXMLConverter(persister))
.setClient(new OkClient(okHttpClient))
.setLogLevel(RestAdapter.LogLevel.NONE)
.build()
.create(RetrofitRecordingService.class));
}
//...
}
public interface RetrofitRecordingService {
#GET("/getScheduledPrograms")
ScheduledRecordsXML getScheduledPrograms(#Query("UserID") String userId);
}
public interface ServiceComponent {
RecordingService RecordingService();
//...
}
public interface AppDomainComponent
extends InteractorComponent, ServiceComponent, ManagerComponent, ParserComponent {
}
#Singleton
#Component(modules = {
//...
InteractorModule.class,
ManagerModule.class,
ServiceModule.class,
ParserModule.class
//...
})
public interface ApplicationComponent
extends AppContextComponent, AppDataComponent, AppDomainComponent, AppUtilsComponent, AppPresentationComponent {
void inject(DashboardActivity dashboardActivity);
//...
}

Do I have to call DaggerLoggerComponent in every class I want to get some components like my Logger class?
Yes for all classes that created by the system like Application, Activity and Service. but for you own classes, you don't need that. just annotate you constructor with #inject and dagger will provide your dependencies.
Also how can I make the scope of the Logger class a singleton? Right
now every button click creates a new logger instance.
Your setup for singleton is correct. but you have to initialize the component one time after the activity is created (onCreate) in order to let dagger to inject all fields. Also you can utilize lazy injection feature if you don't need the Logger object right away.
#Inject
Logger logger;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
LoggerComponent component = DaggerLoggerComponent.builder().loggerModule(new LoggerModule()).build();
component.inject(this);
init();
}
Then you can access your object without take the reference from the component:
private void init(){
button = (Button)findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
logger.log("Hello!",MainActivity.this);
}
});
}
In summary:
You have to initialize the component in all classes that use field injections.
UPDATE:
To do the actual injection, you have to declare inject() method into your component and dagger will automatically implement it. This method will take care of provide any object annotated with #Inject.