Question

在我的Android应用程序中，我使用mvvm模式跟随架构组件。我的应用程序进行网络调用以显示天气信息。正在从存储库调用调用。该存储库返回对视图模型的响应的居住数据，该调用由我的主要活动观察。

该应用程序正常工作，除了一个条件，每当我断开互联网以测试失败案例时，它会根据需要膨胀错误视图

在错误视图中我有一个重试按钮，这使得方法调用再次观察视图模型（这个方法也是第一次被oncreate（）调用，这有效）

即使在打开互联网并点击侦听observable的重试按钮后，数据也会变为空。

我不知道为什么。请任何人帮忙

REPOSITORY

@Singleton public class ContentRepository {

@Inject AppUtils mAppUtils;
private RESTService mApiService;

@Inject public ContentRepository(RESTService mApiService) {
 this.mApiService = mApiService;
}

 public MutableLiveData<ApiResponse<WeatherModel>> getWeatherListData() {
final MutableLiveData<ApiResponse<WeatherModel>> weatherListData = new                     MutableLiveData<>();
  mApiService.getWeatherList().enqueue(new Callback<WeatherModel>() {
  @Override public void onResponse(Call<WeatherModel> call,                          Response<WeatherModel> response) {
    weatherListData.setValue(new ApiResponse<>(response.body()));
  }

  @Override public void onFailure(Call<WeatherModel> call, Throwable t) {
    weatherListData.setValue(new ApiResponse<>(t));
  }
});
return weatherListData;
}
}

视图模型

public class HomeViewModel extends AndroidViewModel {

private final LiveData<ApiResponse<WeatherModel>> weatherListObservable;

 @Inject public HomeViewModel(Application application, ContentRepository contentRepository) {
super(application);
this.weatherListObservable = contentRepository.getWeatherListData();
}

 public LiveData<ApiResponse<WeatherModel>> getWeatherListObservable() {
return weatherListObservable;
}
}

活动中的观察方法

private void observeViewModel() {
mHomeViewModel = ViewModelProviders.of(this, mViewModelFactory).get(HomeViewModel.class);
mHomeViewModel.getWeatherListObservable().observe(this, weatherModelApiResponse -> {
  if (weatherModelApiResponse.isSuccessful()) {
    mErrorView.setVisibility(View.GONE);
    mBinding.ivLoading.setVisibility(View.GONE);
    try {
      setDataToViews(weatherModelApiResponse.getData());
    } catch (ParseException e) {
      e.printStackTrace();
    }
  } else if (!weatherModelApiResponse.isSuccessful()) {
    mBinding.ivLoading.setVisibility(View.GONE);
    mDialogUtils.showToast(this, weatherModelApiResponse.getError().getMessage());
    mErrorView.setVisibility(View.VISIBLE);
  }
});
}

重新开始活动

@Override public void onClick(View v) {
switch (v.getId()) {
  case R.id.btn_retry:
    mErrorView.setVisibility(View.GONE);
    observeViewModel();
    break;
}
}

第二次观察viewmodel在android中返回null

0 个答案: