android-livedata

问题 I have some problem in nested fragment in Kotlin. I have nested fragment with ViewModel. After resuming fragment from back button press all observers on viewModel LiveData triggers again although my data does not changed. First i googled and tried for define observer in filed variable and check if it is initialized then do not observer it again: lateinit var observer: Observer fun method(){ if (::observer.isInitialized) return observer = Observer{ ... } viewModel.x_live_data.observe

问题 I want to update a member variable of an object inside my Repository on a LiveData- Object. The problem is, that if I call the getValue() Method, I keep getting an NullPointerException, although the value does exist inside my Room- Library. My question now is, how do I get the value from the LiveData Object without calling the observe() Method? (I am not able to call the observe method inside my repository, cause that method wants me to enter a LifeCycleOwner- reference, which is not present

问题 I want to update a member variable of an object inside my Repository on a LiveData- Object. The problem is, that if I call the getValue() Method, I keep getting an NullPointerException, although the value does exist inside my Room- Library. My question now is, how do I get the value from the LiveData Object without calling the observe() Method? (I am not able to call the observe method inside my repository, cause that method wants me to enter a LifeCycleOwner- reference, which is not present

问题 my manifest <receiver android:name=".ui.receiver.NetworkChangeReceiver" > <intent-filter> <action android:name="android.net.conn.CONNECTIVITY_CHANGE" /> <action android:name="android.net.wifi.WIFI_STATE_CHANGED" /> </intent-filter> </receiver> and NetworkChangeReceiver Class class NetworkChangeReceiver : BroadcastReceiver() { override fun onReceive(context: Context?, intent: Intent?) { val connMgr = context?.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager val

问题 I have a listview in my fragment UI that its elements set depend on status of a value that come from a viewmodel LiveData attribute. I want to create instrumental test for the fragment which englobes 3 scenarios test case related to the value set of that attribute and I don't where to start. My code should kind look like below : class MyViewModel : ViewModel() { var status = MutableLiveData("") } class MyFragment : Fragment() { private lateinit var myViewModel: MyViewModel private lateinit

问题 Google's android architecture components tutorial here has a part that explains how to abstract the logic of getting data over the network. In it, they create an abstract class called NetworkBoundResource using LiveData to create a reactive stream as the basis for all reactive network requests. public abstract class NetworkBoundResource<ResultType, RequestType> { private final AppExecutors appExecutors; private final MediatorLiveData<Resource<ResultType>> result = new MediatorLiveData<>();

问题 I have a Fragment with a TextView that opens a custom DialogFragment with a RecyclerView list in it. I am using an MVVM structure with a ViewModel, Dao, and Repository to populate the RecyclerView list with a POJO item (Currency). Whenever I install or restart the app, there is a delay in the RecyclerView list being populated. It initially shows the DialogFragment with no data in it and from using the debugger, it seems that it only populates once the onChanged method is called for my

问题 I have recently seen a weird issue that is acting as a barrier to my project. Multiple calls to set the live data value does not invoke the observer in the view. It seems that only the last value that was set actually invokes the Observer in the view. Here is the code snippet for a review. MainActivity.kt class MainActivity : AppCompatActivity() { private lateinit var viewModel: MainViewModel override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState)

问题 I have recently seen a weird issue that is acting as a barrier to my project. Multiple calls to set the live data value does not invoke the observer in the view. It seems that only the last value that was set actually invokes the Observer in the view. Here is the code snippet for a review. MainActivity.kt class MainActivity : AppCompatActivity() { private lateinit var viewModel: MainViewModel override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState)

问题 What is a proper way to communicate between the ViewModel and the View , Google architecture components give use LiveData in which the view subscribes to the changes and update itself accordingly, but this communication not suitable for single events, for example show message, show progress, hide progress etc. There are some hacks like SingleLiveEvent in Googles example but it work only for 1 observer. Some developers using EventBus but i think it can quickly get out of control when the