Null pointer Exception on UseContex class while using 'printToast()' method of UseContex class.UseContex class extends the mainActivity.If i print toast in MainActivity than it doe's not contain null pointer on context object but same thing don in UseContex than it show null pointer exception.
@Singleton @Component(modules = {AppModule.class})
public interface AppComponent {
void inject(DaggerApplication daggerApplication);
void inject(MainActivity mainActivity);
}
@Module
public class AppModule {
private final DaggerApplication application;
public AppModule(DaggerApplication application) {
this.application = application;
}
@Singleton
@Provides
Context providesApplicationContext(){
return application;
}
@Singleton
@Provides
UseContex provideUsecontex(){
return new UseContex();
}
}
public class UseContex extends MainActivity{
public void printToast(){
Log.e("User dao impl","Hello user dao");
Toast.makeText(context, "helo", Toast.LENGTH_SHORT).show();
}
}
public class MainActivity extends AppCompatActivity {
@Inject
UseContex useContex;
@Inject
public Context context;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
((DaggerApplication)getApplication()).getAppComponent().inject(this);
useContex.printToast();
}
}
public class DaggerApplication extends Application {
AppComponent appComponent;
@Override
public void onCreate() {
super.onCreate();
appComponent = DaggerAppComponent.builder().appModule(new
AppModule(this)).build();
appComponent.inject(this);
}
public AppComponent getAppComponent(){return appComponent;}
}
Dagger is not injecting your UseContex subclass because AppComponent does not @provide a UseContex. AppComponent is only @providing a MainActivity and you're passing in a UseContex as its polymorphic base class and hoping that that works. Instead, @provide a UseContex in your AppComponent and Dagger will inject your base class fields.