[Dagger] integration with workers (For Java People)

readme-dagger-java.md

Android Dagger (Java)

This files have been created in 2017 when Google introduced for the first time Android Jetpack Workers.

This implementation show how to use Dagger with Workers

The above usage might been deprecated since now we have Hilt

AndroidWorkerInjection.java

public class AndroidWorkerInjection {

    public static void inject(Worker worker) {
        checkNotNull(worker, "worker");
        Object application = worker.getApplicationContext();
        if (!(application instanceof HasWorkerInjector)) {
            throw new RuntimeException(
                    String.format(
                            "%s does not implement %s",
                            application.getClass().getCanonicalName(),
                            HasWorkerInjector.class.getCanonicalName()));
        }

        AndroidInjector<Worker> workerInjector =
                ((HasWorkerInjector) application).workerInjector();
        checkNotNull(workerInjector, "%s.workerInjector() returned null", application.getClass());
        workerInjector.inject(worker);
    }
}

AndroidWorkerInjectionModule.java

@Module
public abstract class AndroidWorkerInjectionModule {

    @Multibinds
    abstract Map<Class<? extends Worker>, AndroidInjector.Factory<? extends Worker>>
        workerInjectorFactories();
}

AppComponent.java

@Singleton
@Component(modules = {
        AndroidSupportInjectionModule.class,
        AndroidWorkerInjectionModule.class,
        WorkerModule.class})
public interface AppComponent {
    @Component.Builder
    interface Builder {
        @BindsInstance
        Builder application(MyApplication application);
        AppComponent build();
    }
    void inject(MyApplication app);
}

HasWorkerInjector.java

public interface HasWorkerInjector {
    AndroidInjector<Worker> workerInjector();
}

MyApplication.java

public class MyApplication extends MultiDexApplication implements HasWorkerInjector {
    
    @Inject DispatchingAndroidInjector<Worker> workerDispatchingAndroidInjector;

    public AppComponent appComponent;

    @Override
    public void onCreate() {
        super.onCreate();
        MultiDex.install(this);
        appComponent = DaggerAppComponent
                .builder()
                .application(this)
                .build();
        appComponent.inject(this);
      
        //Call the Profile Worker
        OneTimeWorkRequest refreshProfile =
        new OneTimeWorkRequest.Builder(ProfileWorker.class)
                .addTag(ConstantsUtils.TAG_OUTPUT)
                .build();
        WorkManager.getInstance().enqueue(refreshProfile);   
    }

    @Override
    public AndroidInjector<Activity> activityInjector() {
        return dispatchingAndroidInjector;
    }


    @Override
    public AndroidInjector<Worker> workerInjector() {
        return workerDispatchingAndroidInjector;
    }
}

ProfileWorker.java

public class ProfileWorker extends Worker {

    @Inject
    SomeClass clazz;

    @NonNull
    @Override
    public WorkerResult doWork() {
        AndroidWorkerInjection.inject(this);
        // Do work here :
        return WorkerResult.SUCCESS;
    }
}

ProfileWorkerModule.java

@Subcomponent
public interface ProfileWorkerModule extends AndroidInjector<ProfileWorker> {

    @Subcomponent.Builder
    abstract class Builder extends AndroidInjector.Builder<ProfileWorker>{}
}

WorkerKey.java

@Documented
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@MapKey
public @interface WorkerKey {
    Class<? extends Worker> value();
}

WorkerModule.java

@Module(subcomponents = {
        ProfileWorkerModule.class,
        UploadWorkerModule.class
})
public abstract class WorkerModule {

    @Binds
    @IntoMap
    @WorkerKey(ProfileWorker.class)
    abstract AndroidInjector.Factory<? extends Worker> bindProfileWorkerFactory(ProfileWorkerModule.Builder profileWorker);
}

@cbeyls : you can still use this. Dagger is a Java library that has been used on Android. Now they made a much simpler way to do DI using Hilt.

But personally I like Koin much more!!