android-viewmodel

问题 I'm using a navigation-component in my application and also using shared ViewModel between multiple fragments that are in the same graph. Now I want to instantiate the ViewModel with this graph scope with this. As you know, in fragments we should inject objects ( ViewModel,..etc ) in onAttach: but when I want to do this (injecting ViewModel with a graph scope in onAttach ), this error occurs: IllegalStateException: NavController is not available before onCreate() Do you how can I do this? 回答1

问题 I'm using a navigation-component in my application and also using shared ViewModel between multiple fragments that are in the same graph. Now I want to instantiate the ViewModel with this graph scope with this. As you know, in fragments we should inject objects ( ViewModel,..etc ) in onAttach: but when I want to do this (injecting ViewModel with a graph scope in onAttach ), this error occurs: IllegalStateException: NavController is not available before onCreate() Do you how can I do this? 回答1

问题 As I understand when we call this code in fragments, we will have a viewmodel instance from activity ViewModelStore: viewModel = ViewModelProviders.of(activity!!).get(SharedViewModel::class.java) When fragments will end their lifecycle, the instance of this viewmodel will exist in ViewModelStore until the destruction of activity. ViewModelStore has a clear() method, but it clears all viewmodels in it. Is there some way to clear specific ViewModel? Another solution is to scope ViewModel to

问题 As I understand when we call this code in fragments, we will have a viewmodel instance from activity ViewModelStore: viewModel = ViewModelProviders.of(activity!!).get(SharedViewModel::class.java) When fragments will end their lifecycle, the instance of this viewmodel will exist in ViewModelStore until the destruction of activity. ViewModelStore has a clear() method, but it clears all viewmodels in it. Is there some way to clear specific ViewModel? Another solution is to scope ViewModel to

问题 With android Paging library it is really easy to load data from Database in chunks and ViewModel provides automatic UI update and data survival. All these frameworks modules help us create a great app in android platform. A typical android app has to show a list of items and allows user to search that list. And this what I want to achieve with my app. So I have done an implementation by reading many documentations, tutorials and even stackoverflow answers. But I am not so sure whether I am

问题 I'm building a location app where I display background locations from a Room database in my MainActivity. I can get a ViewModel by calling locationViewModel = ViewModelProviders.of(this).get(LocationViewModel.class); locationViewModel.getLocations().observe(this, this); Periodic background locations should be saved to the Room database when I receive location updates via a BroadCastReceiver. They should be saved by calling locationViewModel.getLocations().setValue() public class

问题 I'm building a location app where I display background locations from a Room database in my MainActivity. I can get a ViewModel by calling locationViewModel = ViewModelProviders.of(this).get(LocationViewModel.class); locationViewModel.getLocations().observe(this, this); Periodic background locations should be saved to the Room database when I receive location updates via a BroadCastReceiver. They should be saved by calling locationViewModel.getLocations().setValue() public class

问题 I am working on an app that queries the github api to get a list of user and i'm following the recommended android architecture component guide. Once the data is fetched from the network, I store it locally using Room DB and then display it on the UI using ViewModel that observes on the LiveData object (this works fine). However, I want to be able to have a button which when clicked would trigger a refresh action and perform a network request to get new data from the API if and only if there

问题 I am working on an app that queries the github api to get a list of user and i'm following the recommended android architecture component guide. Once the data is fetched from the network, I store it locally using Room DB and then display it on the UI using ViewModel that observes on the LiveData object (this works fine). However, I want to be able to have a button which when clicked would trigger a refresh action and perform a network request to get new data from the API if and only if there

问题 I'm using the navigation component, I want a view model to be shared between a few fragments but they should be cleared when I leave the fragments (hence not scoping them to the activity) I'm trying to take the one activity many fragments approach. I have managed to achieve this using multiple nav hosts and scoping the fragments to it using getParentFragment but this just leads to more issues having to wrap fragments in other parent fragments, losing the back button working seamlessly and