尝试在空对象引用上调用虚拟方法 'void android.arch.lifecycle.MutableLiveData.setValue(java.lang.Object)'

Question

我使用 Android 架构组件并尝试实例化视图模型并从 LiveData 观察数据。但是我收到以下错误：

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;
}

Answer 1

像这样更新你的函数..

public class ActivationRepository {

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

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