Dagger: Dagger Application injection NPE

[luispereira]

I'm trying to inject some objects on application, in order to access them whenever I want.
So, on my application I'm doing something like this:

private static AppComponent mApplicationComponent;

@Override
    public void onCreate() {
        …
       mApplicationComponent = DaggerAppComponent.builder()
                .appModule(new AppModule(this, new ModuleSpref(this))
                .build();
   }

 public static AppComponent getInstance() {
        return mApplicationComponent;
    }

However, according to google crash log of my production app, the application has a NullPointException when trying to access anything from getInstance(). On my application this happens on a service which is only called via a receiver. Additionally, this also happens on another receiver.

 MyApplication.getInstance().context(); //Null Point Exception :(

Here is my ApplicationComponent:

@Component(modules = AppModule.class)
@Singleton
public interface AppComponent {
    void inject(Context context);

    //Exposed to sub-graphs.
    Context context();
    ModuleSpref getSpref();
}

I tried many times to replicate, but so far without success, despite the google crash saying otherwise.
Am I doing something wrong here?
As far as I know, for services/receivers to be initialised in android, the application must first be initialised, so getInstance() should not return null right?

[ronshapiro]

Take a look at https://google.github.io/dagger/api/latest/dagger/android/DaggerApplication.html, which handles this scenario where sometimes a contentprovider.oncreate() is called before the application.oncreate()

[luispereira]

I can't see the link (404) for me.

[luispereira]

Also, getInstance() is only called on onReceiver() of broadcast or on startCommand() of service

[tbroyer]

Ron probably got his markdown mixed up and meant DaggerApplication

[luispereira]

Thanks, so if I undestrood correctly, injecting my objects on a DaggerApplication class will prevent this injection before application.oncreate() right?
Also, is there any exemple with DaggerApplication?

[luispereira]

I'm actually trying to do something about this,

public MyApplication extends DaggerApplication implements AndroidInjector<MyApplication>

When I notice that AndroidInjector only has, broadcast, service, activity, fragment or contentprovider.

So, how should I proceed when overriding the method applicationInjector on application?

  @Override
    protected AndroidInjector<? extends DaggerApplication> applicationInjector() {
        return this;
    }

    @Override
    public void inject(MyApplication myApplication) {
        //this does not exist, so how can I create a AndroidInjector for application? or am I missing somthing?
        AndroidInjector<MyApplication> applicationInjector = ((HasApplicatiomInjector) myApplication).applicationInjector();
        applicationInjector.inject(this);
    }

Since I'm only injecting this to access it from everywhere, activities, services and broadcasts.

[matpag]

I'm stucked at the same point, i'm pretty new to Dagger 2 and there is no documentation on how to use the new DaggerApplication class (every tutorial online is somehow not updated)

[luispereira]

As a side note, this NPE on injected instance happens a lot on services from startCommand() and on samsung devices such as Galaxy S8, S7 and S6

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        MyApplication.getInstance().context(); //just to text if no npe is given

        (...) 

        return START_REDELIVER_INTENT;
    }

[ronshapiro]

Github isn't the best forum for this - please use StackOverflow with the dagger-2 tag instead, as that is a better forum for questions.

[juliahexen]

@luispereira Did you find any solution for your problem? Same here :/

[luispereira]

Actually I found a work around for this which implies something like this on your application class:

public class MyApplication extends Application {
    private static MyApplication sInstance;
    private AppComponent applicationComponent;

    public MyApplication() {
        sInstance = this;
    } 

    public static AppComponent getInstance() {
        return sInstance.getAppComponent();
    }

    private AppComponent getAppComponent() {
        if (applicationComponent == null) {
            //initialise the dagger stuff here
        }
        return applicationComponent;
    }
}

Basically, if by any instance, the dagger app component builder returns null, it will force to initialise again. I know this is far from a perfect solution, but it works.

PS: I had multiple reports of different projects which the application was started after services/brodcasts and even activities on Samsung devices. I'm still investigating the issue, but I seen that Samsung starts a content provider for every application, maybe triggering this kind of behaviour. Although, with the above solution this kind of NPE no longer happened

[juliahexen]

Thank you very much, I will try it :)

[dnsknr]

I am facing this issue as well and I have no idea how to work around it.

Caused by: java.lang.RuntimeException: 
  at dagger.android.AndroidInjection.inject (AndroidInjection.java:48)
  at dagger.android.support.DaggerAppCompatActivity.onCreate (DaggerAppCompatActivity.java:43)
  at com.package.MainActivity.onCreate (MainActivity.java:83)
  at android.app.Activity.performCreate (Activity.java:6912)
  at android.app.Instrumentation.callActivityOnCreate (Instrumentation.java:1126)
  at android.app.ActivityThread.performLaunchActivity (ActivityThread.java:2900)

This happens only on Android 7.0, mainly on Samsung devices, some Huawai and Motorola devices and a few Xperia devices. I am unable to reproduce it since I do not have any of the affected devices at hand.

It seems this is caused by the application not (yet) being set for the activity, meaning activity's onCreate is called before the activity is actually attached to the application.

Here the affected Dagger code:

https://github.com/google/dagger/blob/e8d7cd4c29c1316c5bb1cf0737d4f29111fcb1c8/java/dagger/android/support/DaggerAppCompatActivity.java#L42-L45

https://github.com/google/dagger/blob/e8d7cd4c29c1316c5bb1cf0737d4f29111fcb1c8/java/dagger/android/AndroidInjection.java#L43-L52

activity.getApplication() returns null, and so the RuntimeException is thrown.

Anyone any suggestions?

[Zhuinden]

Oh this is probably the same problem as what Mortar fixes with

Application app = activity.getApplication();
if(app == null) {
     app = (Application)activity.getApplicationContext();
}

[ronshapiro]

@Zhuinden is this what you're referring too: https://github.com/square/mortar/commit/bf74e3e0ad00713c3123b957a61f82bd73b578b5?

Is there any reason to not just call (Application) activity.getApplicationContext() here then and not worry about the null-check?

/cc @rjrjr @loganj

[JakeWharton]

No

On Tue, Oct 17, 2017, 12:12 PM Ron Shapiro [e-mail] wrote:

@Zhuinden https://github.com/zhuinden is this what you're referring
too: square/mortar@bf74e3e
https://github.com/square/mortar/commit/bf74e3e0ad00713c3123b957a61f82bd73b578b5
?

Is there any reason to not just call (Application)
activity.getApplicationContext() here then and not worry about the
null-check?

/cc @rjrjr https://github.com/rjrjr @loganj https://github.com/loganj

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[dnsknr]

Hi everyone,

I rolled out an update a few hours ago with the change @Zhuinden proposed based on Dagger's DaggerAppCompatActivity and the AndroidInjection class:

public abstract class MyDaggerAppCompatActivity extends AppCompatActivity implements HasFragmentInjector, HasSupportFragmentInjector {

    @Inject DispatchingAndroidInjector<Fragment> supportFragmentInjector;
    @Inject DispatchingAndroidInjector<android.app.Fragment> frameworkFragmentInjector;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        inject();
        super.onCreate(savedInstanceState);
    }

    @Override
    public AndroidInjector<Fragment> supportFragmentInjector() {
        return supportFragmentInjector;
    }

    @Override
    public AndroidInjector<android.app.Fragment> fragmentInjector() {
        return frameworkFragmentInjector;
    }

    private void inject() {
        Application application = getApplication();
        if(application == null) {
            application = (Application) getApplicationContext();
        }

        if (!(application instanceof HasActivityInjector)) {
            throw new RuntimeException(String.format("%s does not implement %s", application.getClass().getCanonicalName(), HasActivityInjector.class.getCanonicalName()));
        }

        AndroidInjector<Activity> activityInjector = ((HasActivityInjector) application).activityInjector();
        checkNotNull(activityInjector, "%s.activityInjector() returned null", application.getClass().getCanonicalName());

        activityInjector.inject(this);
    }

}

Still getting the RuntimeException, now thrown by my code above. So looks like that either there is an application but the wrong one or even the application context is null. Cannot imagine how any of both scenarios would work actually...

[dnsknr]

I tested using getApplicationContext() instead of getApplication() in all Dagger 2 components I am using (DaggerAppCompatActivity, DaggerIntentService, DaggerFragment) and I can confirm that it does not make any difference. This version is now rolled out to over 300k users and the exception rate is no different to the original version based on unchanged Dagger 2.12 code.

See also https://stackoverflow.com/questions/46784685/runtimeexception-with-dagger-2-on-android-7-0-and-samsung-devices where I posted some code where I tried to get more understanding of this error without any luck.

[tbroyer]

See also https://github.com/google/dagger/issues/891

[dnsknr]

I solved the issue for myself by not using anymore the DaggerApplication but an Application independent solution described here: https://stackoverflow.com/a/46925736/8788319

Not sure if this is an option for Dagger 2 but I did not find another way to resolve the crashes under Android 7.0 otherwise.

[abhiroopnray]

Hope you had added application class name in the Android Manifest file. Without it, the app will work but the dagger component will be null.

[ronshapiro]

I'm still pretty dumbfounded at what is happening here. I wish I had a better suggestion at what we should do.

[pablobaxter]

One interesting thing to point out is that Android doesn't always run any of the ContentProvider classes or the Application class listed in the manifest. https://developer.android.com/guide/topics/data/autobackup#ImplementingBackupAgent

Specifically...

I've tested to see if Services and BroadcastReceivers still ran, and they do. This was causing multiple issues for me with Fabric, Firebase, and Dagger. I figured I'd share my findings here as I referenced this issue to try to fix my Dagger problem.

I'm in the process of disabling this auto backup (setting allowBackup="false" in the AndroidManifest) for the app I work on to validate my fix. I'll post my findings if it fixes my Dagger issue.

[camsteffen]

@pablobaxter Any update?

[pablobaxter]

@pablobaxter Any update?

@camsteffen Thank you for reminding me! Also sorry... I never did update my result on this thread as promised.

So disabling the backup worked for me. I am no longer seeing my Dagger crash, which in my case was a ClassCastException due to getApplication() not being an instance of DaggerApp, even though I extend it. This also solved one of the other issues I had, which would only ever happen if my extended Application class never ran.

I filed a ticket about this with Firebase (https://github.com/firebase/firebase-android-sdk/issues/1456), as this was the main library starting Services and BroadcastReceivers while the app was in this restricted mode. However, this is most likely an Android OS issue. It looks like whenever the app crashes in this restricted mode (in my case due to Firebase starting up), the next launch app (user initiated or otherwise) restarts the app in this restricted mode, which caused a crash, and so on.

Hope this helps!

[camsteffen]

@pablobaxter Thanks for the update! It looks like your firebase bug report is attracting some more needed attention so I will follow that, even though I don't use firebase myself. I wonder if disabling backup would prevent this issue in all cases.

[Chang-Eric]

Closing this as I don't think there is much that can be done on the Dagger side. This feels like an Android bug that you can ever be called without the Application specified in the manifest.

[camsteffen]

Given the Android docs quoted and the SO solution mentioned, would it make sense for Dagger to provide a solution to work without overriding Application?

[pablobaxter]

As an FYI, I did file a bug with the Android team regarding the backup agent. https://issuetracker.google.com/u/1/issues/160946170

[Chang-Eric]

@camsteffen if I understand the SO solution, it is just moving the component to a static variable? This would work for the production app, but keeping your DI graph in static state tends to cause problems for things like tests.

[Zhuinden]

@camsteffen if I understand the SO solution, it is just moving the component to a static variable? This would work for the production app, but keeping your DI graph in static state tends to cause problems for things like tests.

That's never bothered anyone using Koin, which works exactly the same way.