Attempt to invoke virtual method 'void android.arch.lifecycle.MutableLiveData.setValue(java.lang.Object)' on a null object reference

Question

I use Android architecture components and tried to instantiate viewmodel and Observe data from LiveData. But im getting the following error :

ActivationFragment.clas:

@OnClick(R.id.btn_activation)
public void onEvaluateClick(Button v) {
    maActivationCode = etActivation.getText().toString();
    mActiationViewModel.getsatusCode(maActivationCode).observe(this, new Observer<Boolean>() {
        @Override
        public void onChanged(@Nullable Boolean aBoolean) {
        } 
    });
}

ActivationViewModel class:

public class ActivationViewModel  extends ViewModel{

public ActivationRepository activationRepository;

public ActivationViewModel(ActivationRepository activationRepository) {
    this.activationRepository = activationRepository;
}

public LiveData<Boolean> getsatusCode(String activationCode) {
    return (LiveData<Boolean>)  activationRepository.getStatusCode(activationCode);
}

}

ActivationRepository class:

public class ActivationRepository {

public MutableLiveData<Boolean> status;

public MutableLiveData<Boolean> getStatusCode(String activationCode) {
    status.setValue(Boolean.valueOf(false));
    return status;
}

Solution

Update your function like this..

public class ActivationRepository {

public MutableLiveData<Boolean> status = new MutableLiveData<>();

 public MutableLiveData<Boolean> getStatusCode(String activationCode) {
    status.postValue(Boolean.valueOf(false));
    return status;
}

Comments

[Nikolas Bozic]

Omg, what a lame mistake, It works as this , thanks a lot

[Santanu Sur]

update ..the answer.. if it worked.. btw how r you ? i dint get time..could nt look at your git project.. :(

[Nikolas Bozic]

Y i will check as correct, I am fine, how r u, I fixed that project, so no worries:)

[woodii]

the problem was not postValue() which is prefered in general (because it runs not on the mainthread in comparison to setValue()). You just forgot to initialize your status object with new MutableLiveData<>(); A somewhat misleading error message ;)