Inject classes into workmanager with dagger2 (java)

Question

the trouble is that I can't to inject classes with dagger2 into worker (WorkManager) with java.

I've tried to understand the explanation of it here: https://proandroiddev.com/dagger-2-setup-with-workmanager-a-complete-step-by-step-guild-bb9f474bde37 And I don't know why - but in my case, it is won't work.

public class SimpleWorker extends androidx.work.Worker {

private String TAG = "SimpleWorker";

SomeModel someModel; // this is injected model

public SimpleWorker(@NonNull Context context, @NonNull WorkerParameters 
    workerParams) {
    super(context, workerParams);
}

@NonNull
@Override
public Result doWork() {
    Log.d(TAG, someModel.toString()); // but here always null
    return Result.success(); }
}

I wanted it works well!

YES - it is a repeat of my question WorkManager Java Android Dagger2 but it closed by moderators and I did not have time to answer it. I really want to save some time for other people. ps. Pls - don't delete it.

Answer 1

And there is the answer for people like me:

Here it is Worker class:

import android.content.Context;
import android.support.annotation.NonNull;
import android.util.Log;

import androidx.work.ListenableWorker;
import androidx.work.WorkerParameters;

import javax.inject.Inject;
import javax.inject.Provider;

import com.sampleapp.model.Model;

public class SimpleWorker extends androidx.work.Worker {

//dagger (what we want to Inject into worker) U CAN ADD WHATEVER NEEDED
private Model model;

//not dagger (just some fields)
private String someField;
private final String TAG = getClass().getSimpleName();

private SimpleWorker(@NonNull Context context,
                     @NonNull WorkerParameters workerParams,
                     Model model) {
    super(context, workerParams);
    this.model = model;

    someField = "just some work";
}

@NonNull
@Override
public ListenableWorker.Result doWork() {
    Log.d(TAG, "Worker starts");
    Log.d(TAG, model.getClass().getSimpleName() + " doing some work");
    Log.d(TAG, "Job done!");
    return ListenableWorker.Result.success();
}

public static class Factory implements ChildWorkerFactory {

    private final Provider<Model> modelProvider;

    @Inject
    public Factory(Provider<Model> modelProvider) {
        this.modelProvider = modelProvider;
    }

    @Override
    public ListenableWorker create(Context context, WorkerParameters workerParameters) {
        return new SimpleWorker(context,
                workerParameters,
                modelProvider.get());
    }
}
}

Interface is:

public interface ChildWorkerFactory {
ListenableWorker create(Context appContext, WorkerParameters workerParameters);
}

WorkerFactory:

import android.content.Context;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;

import java.util.Map;

import javax.inject.Inject;
import javax.inject.Provider;

import androidx.work.ListenableWorker;
import androidx.work.WorkerFactory;
import androidx.work.WorkerParameters;

import com.sampleapp.model.Model;
import com.sampleapp.model.CollectionsUtil;
public class SimpleWorkerFactory extends WorkerFactory {

private final Map<Class<? extends ListenableWorker>, Provider<ChildWorkerFactory>> workersFactories;

@Inject
public SimpleWorkerFactory(Map<Class<? extends ListenableWorker>, Provider<ChildWorkerFactory>> workersFactories) {
    this.workersFactories = workersFactories;
}

@Nullable
@Override
public ListenableWorker createWorker(@NonNull Context appContext, @NonNull String workerClassName, @NonNull WorkerParameters workerParameters) {
    Provider<ChildWorkerFactory> factoryProvider = CollectionsUtil.getWorkerFactoryProviderByKey(workersFactories, workerClassName);
    return factoryProvider.get().create(appContext, workerParameters);
}
}

CollectionUtils:

/**
 *
 * @param map workers
 * @param key workers name (class name)
 * @return
 */
public static Provider<ChildWorkerFactory> getWorkerFactoryProviderByKey(Map<Class<? extends ListenableWorker>, Provider<ChildWorkerFactory>> map, String key) {
    for (Map.Entry<Class<? extends ListenableWorker>, Provider<ChildWorkerFactory>> entry : map.entrySet()) {
        if (Objects.equals(key, entry.getKey().getName())) {
            return entry.getValue();
        }
    }
    return null;
}

Worker binding:

import dagger.Binds;
import dagger.Module;
import dagger.multibindings.IntoMap;

@Module
public interface WorkerBindingModule {
    @Binds
    @IntoMap
    @WorkerKey(SimpleWorker.class)
    ChildWorkerFactory bindHelloWorldWorker(SimpleWorker.Factory factory);
}

WorkerKey annotation:

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import androidx.work.ListenableWorker;
import dagger.MapKey;

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

Part of Application class:

private static AppComponent component;

private void configureWorkManager() {
    UpdaterWorkerFactory factory = component.factory();
    Configuration config = new Configuration.Builder()
            .setWorkerFactory(factory)
            .build();

    WorkManager.initialize(this, config);
}

Part of AppComponent interface:

@Singleton
@Component(modules = {AppModule.class, WorkerBindingModule.class})
public interface AppComponent {
    // Some other injects here
    SimpleWorkerFactory factory();
}

And part of manifest (inside of Application):

<provider
        android:name="androidx.work.impl.WorkManagerInitializer"
        android:authorities="${applicationId}.workmanager-init"
        android:exported="false"
        tools:node="remove"/>

What was in gradle:

// (Java only)
implementation ("android.arch.work:work-runtime:1.0.1")

ps. And IF it will get some conflicts with firebase

api 'com.google.guava:guava:27.1-android'

Notice: In my case Model was injected throw Interface. like:

public class ModelImplementation implements Model {
private ModelImplementation() {
    App.getComponent().inject(this);
}
}

In the same AppComponent!

to use this amazing feature just use something like (in Activity for example):

PeriodicWorkRequest periodicWorkRequest = new PeriodicWorkRequest.Builder(SimpleWorker.class, 
Const.WORKER_PERIOD, TimeUnit.MINUTES).build();
    WorkManager.getInstance().enqueue(periodicWorkRequest);

pps. Const.WORKER_PERIOD - a period in minutes (min 15)

targetSDK is 27