MutableLiveData值未反映在View类中

问题描述

我正在通过数据绑定实现MVVM模式。问题在于MutableLiveData值未反映在View类中。我的视图课如下：

public class SettingsFragment extends Fragment {
SettingsViewModel settingsViewModel;
public View onCreateView(@NonNull LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState) {

    SettingsRepository repository = new SettingsRepository(getContext());
    SettingsFactory factory = new SettingsFactory(repository);

    FragmentSettingsBinding binding = DataBindingUtil.inflate(inflater,R.layout.fragment_settings,container,false);
    settingsViewModel = new ViewModelProvider(this,factory).get(SettingsViewModel.class);

    binding.setViewModel(settingsViewModel);



    return binding.getRoot();
}

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    settingsViewModel.getFeedbackResponse().observe(getActivity(),response -> {
        Log.e("inside",response.getMessage());

    });
}}

我正在发布一个Log Inside视图类，但是它从未被调用。

我的 viewModel 类如下：

public class SettingsViewModel extends ViewModel {

public static String SWITCH_KEY = "SWITCH_KEY";
SettingsRepository repository;
MutableLiveData<Feedback> feedbackMutableLiveData;

public SettingsViewModel(SettingsRepository repository) {
    this.repository = repository;
    feedbackMutableLiveData = new MutableLiveData<>();
}

//show feedback form
public void onFeedbackClicked(View view) {

    AppUtil.showFeedbackDialog(view.getContext(),new AppUtil.FeedbackListener() {
        @Override
        public void onSubmitFeedback(FeedbackBody feedbackBody) {
            Log.e("inside","response");
            feedbackMutableLiveData = repository.sendFeedback(feedbackBody);

        }
    });
}


public LiveData<Feedback> getFeedbackResponse() {
    return feedbackMutableLiveData;
}}

我的存储库类别是：

public class SettingsRepository extends SafeApiRequest {

    MyApi myApi;
    Context context;
    public SettingsRepository(Context context) {
        SetupRetrofit setupRetrofit = new SetupRetrofit(context);
        this.myApi = setupRetrofit.createService(MyApi.class);
    }

    public MutableLiveData<Feedback> sendFeedback(FeedbackBody feedbackBody) {
        return callRetrofitObjectResponse(context,myApi.sendFeedback("feedback/store",feedbackBody));
    }

}

SafeAPiRequest 类为：

public class SafeApiRequest {
 
    public static <T> MutableLiveData<T> callRetrofitObjectResponse(Context context,Call<T> call) {
        MutableLiveData<T> responseObject = new MutableLiveData<>();
        Log.e("inside",call.request().url() + "------");

        call.enqueue(new Callback<T>() {
            @Override
            public void onResponse(Call<T> call,Response<T> response) {
                Log.e("inside","successfull");
                responseObject.setValue(response.body());
            }

            @Override
            public void onFailure(Call<T> call,Throwable t) {
              
            }
        });

        return responseObject;
    }

}

当用户单击反馈按钮时，将调用onFeedbackClicked方法。在此方法内部，一旦用户单击“提交”按钮，就会调用覆盖方法onSubmitFeedback，其中feedbackMutableLiveData被分配给api调用，该API返回的值是mutablelivedata。但是主要的问题是它的值没有反映在视图类中。我尝试在viewmodel类的构造函数中删除其值的初始化，但是在执行此操作时，它会在我们观察的位置给出NullPointerException。

当我尝试在 view 类中获取feedbackMutableLiveData的值时，这种情况下可能的解决方案是什么。

解决方法

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