The ViewModel hides everything about the backend from the user interface. It provides methods for accessing the UI data, and it returns LiveData so that ... ... <看更多>

You can check live data meal to see if it's empty or null and then trigger with your live data empty like this: In the viewmodel, you create ... ... <看更多>

Fun with LiveData (Android Dev Summit '18). Transformation Setup ... Lots of horrible things happening in this view model, by the way. For starters . ... <看更多>