AndroidViewModel has no zero argument constructor. How to solve this?

Question

I've searched for my problem nearly whole the Internet and couldn't find the answer, which I need. Yes. My question is not unique, but there was no answer, which could help me. So I decided to ask it myself.

Now about the problem:

public class AuthActivityViewModel extends AndroidViewModel {

    Repository repository;
    private LiveData<List<User>> users;
    private LiveData<User> user;

    public AuthActivityViewModel(@NonNull Application application) {
        super(application);

        repository = new Repository(application);
    }

    public LiveData<List<User>> getUsers() {
        users = repository.getUsers();
        return users;
    }

    public LiveData<User> getUser(int userId) {
        user = repository.getUser(userId);
        return user;
    }

    public void addNewUser(User user) {
        repository.insertUser(user);
    }

    public void updateUser(User user) {
        repository.updateUser(user);
    }

    public void deleteUser(User user) {
        repository.deleteUser(user);
    }
}

............................................

public class AuthActivity extends AppCompatActivity implements AuthInteractionListener {

    private FragmentManager fragmentManager;
    private final ConnectionBroadcastReceiver connectionBroadcastReceiver = new ConnectionBroadcastReceiver();

    private int limitOfOnWindowFocusChangedOperationForAuthActivity = 0;
    private boolean isActivityRecreated;

    AuthActivityViewModel authActivityViewModel;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_auth);

        isActivityRecreated = true;
        IntentFilter connectionIntentFilter = new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
        registerReceiver(connectionBroadcastReceiver, connectionIntentFilter);

        authActivityViewModel = new ViewModelProvider(this).get(AuthActivityViewModel.class);
    }
    ...
}

.............

Error:

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.findthepikachuupgradeversion2/com.example.android.findthepikachuupgradeversion3.view.AuthActivity}: java.lang.RuntimeException: Cannot create an instance of class com.example.android.findthepikachuupgradeversion3.viewmodel.AuthActivityViewModel
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3307)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3446)
    at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
    at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
    at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2043)
    at android.os.Handler.dispatchMessage(Handler.java:107)
    at android.os.Looper.loop(Looper.java:224)
    at android.app.ActivityThread.main(ActivityThread.java:7548)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)
 Caused by: java.lang.RuntimeException: Cannot create an instance of class com.example.android.findthepikachuupgradeversion3.viewmodel.AuthActivityViewModel
    at androidx.lifecycle.ViewModelProvider$NewInstanceFactory.create(ViewModelProvider.java:221)
    at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:187)
    at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:150)
    at com.example.android.findthepikachuupgradeversion3.view.AuthActivity.onCreate(AuthActivity.java:44)
    at android.app.Activity.performCreate(Activity.java:7893)
    at android.app.Activity.performCreate(Activity.java:7880)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1307)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3282)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3446) 
    at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) 
    at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
    at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2043) 
    at android.os.Handler.dispatchMessage(Handler.java:107) 
    at android.os.Looper.loop(Looper.java:224) 
    at android.app.ActivityThread.main(ActivityThread.java:7548) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950) 
 Caused by: java.lang.InstantiationException: java.lang.Class<com.example.android.findthepikachuupgradeversion3.viewmodel.AuthActivityViewModel> has no zero argument constructor
    at java.lang.Class.newInstance(Native Method)
    at androidx.lifecycle.ViewModelProvider$NewInstanceFactory.create(ViewModelProvider.java:219)
    at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:187) 
    at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:150) 
    at com.example.android.findthepikachuupgradeversion3.view.AuthActivity.onCreate(AuthActivity.java:44) 
    at android.app.Activity.performCreate(Activity.java:7893) 
    at android.app.Activity.performCreate(Activity.java:7880) 
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1307) 
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3282) 
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3446) 
    at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) 
    at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
    at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2043) 
    at android.os.Handler.dispatchMessage(Handler.java:107) 
    at android.os.Looper.loop(Looper.java:224) 
    at android.app.ActivityThread.main(ActivityThread.java:7548) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)

I tried to add a constructor with no arguments in class AuthActivityViewModel, but got this error

There is no default constructor available in androidx.lifecycle.AndroidViewModel

Advices like
- https://stackoverflow.com/a/54462438/14048134
- Make sure your view model class constructor is public.
- Make sure you have added the dependency in your gradle file for lifecycle
are not actual. Why? Cause they were already as they should be, but I have the error which must not be. As the problem exists, there must be something that I didn't count.

Here is some part of the gradle file:

def lifecycle_version = "2.2.0" implementation "androidx.lifecycle:lifecycle-viewmodel:$lifecycle_version"

implementation "androidx.lifecycle:lifecycle-livedata:$lifecycle_version"

annotationProcessor "androidx.lifecycle:lifecycle-compiler:$lifecycle_version"

def room_version = "2.2.5"

implementation "androidx.room:room-runtime:$room_version"

annotationProcessor "androidx.room:room-compiler:$room_version"

How can I solve this problem?

when this Exception is raised, every time you launch your app? — Zain, Nov 14 '20 at 14:27
Can you add this `implementation 'androidx.lifecycle:lifecycle-extensions$lifecycle_version`.. logically won't change, but just in case — Zain, Nov 14 '20 at 14:33
`LiveData` is one of the libraries that is included in `extensions`, but it also include other libraries, I am doubt that missing any of them can cause this exception, let me check if can find documentation on this. — Zain, Nov 14 '20 at 14:49

Zain · Accepted Answer · 2020-11-16T16:09:40.147

4

Add the below dependency to gradle app module level.

implementation 'androidx.lifecycle:lifecycle-extensions:$lifecycle_version

Extensions include many libraries including LiveData, So, by adding it, you can get rid of:

implementation 'androidx.lifecycle:lifecycle-livedata:$lifecycle_version

But it appears lifecycle-extensions has been deprecated. Is there another dependency that solves this issue?

That is right it's been deprecated as of version:2.2.0.

lifecycle-extensions Artifact Deprecation: With the above deprecation of ViewModelProviders.of(), this release marks the deprecation of the last API in lifecycle-extensions and this artifact should now be considered deprecated in its entirety. We strongly recommend depending on the specific Lifecycle artifacts you need (such as lifecycle-service if you’re using LifecycleService and lifecycle-process if you’re using ProcessLifecycleOwner) rather than lifecycle-extensions as there will not be a future 2.3.0 release of lifecycle-extensions.

As quoted by documentation, you can instead use the specific Lifecycle artifacts: And as we discussed in comments the specific lifecycler aritifacts that works was:

implementation "android.arch.lifecycle:runtime:$lifecycle_version

And also keep the other lifecycler dependency artifacts of yours.

edited Nov 16 '20 at 16:09

answered Nov 14 '20 at 14:49

Zain

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Only please replace "implementation 'androidx.lifecycle:lifecycle-livedata$lifecycle_version" with " implementation 'androidx.lifecycle:lifecycle-livedata:$lifecycle_version", I mean, you're missed the symbol ":". This I want for the other users, not for me. – Ruben Kubalyan Nov 14 '20 at 14:59
@RubenKubalyan can you add `implementation "android.arch.lifecycle:runtime:$lifecycle_version"` instead of `extensions and see.. keep the the same dependencies of yours – Zain Nov 14 '20 at 15:04
1

This solves my issue as well! But it appears lifecycle-extensions [has been deprecated](https://developer.android.com/jetpack/androidx/releases/lifecycle#declaring_dependencies). Is there another dependency that solves this issue? – cshadowstar Nov 15 '20 at 16:01
1

@cshadowstar thanks for raising this.. it was really interesting to me .. I just updated the answer.. question please: does android studio warn you of the deprecation or you got it from documentation... I still can use it and no warnings as of AS 4.0.2 – Zain Nov 16 '20 at 16:11
Thank you for doing that! I also don't get any warnings under AS 4.0.1 , I had got this from the documentation when I was trying to figure out why specifically this solution solved my issue. All the best :) – cshadowstar Nov 16 '20 at 17:24

AndroidViewModel has no zero argument constructor. How to solve this?

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