片段中的ViewModel + LiveData，从ItemDetailFragment导航回去时如何保留ListItemFragment的数据

Question

At the bottom in the onCreateView of ListItemFragment, i make a network call to get all items. like this:

viewmodel.getAllItems()

Then, observe the data to populate items to the RecyclerView. I'm using Navigation Architecture Component to navigate to ItemDetailFragment when User click on each Item. The problem is, when i hit back button, ListItemFragment's onCreateView call again, then viewmodel.getAllItems() also call again. So, what i want is prevent call getAllItems() again, and keep current position of RecyclerView.

Answer 1

YourItemType yourItems; //define this as global field

In onCreateView;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle 
  if(yourItems == null){
     yourItems = viewmodel.getAllItems();
  }
}