View Model keeps creating instance of Live Data

Question

I created the instance of View Model in onCreate method of an activity.

    ticketViewModel = ViewModelProviders.of(this).get(TicketViewModel.cl         


        

Answer 1

If you are willing to do some changes, i think we can handle it in much cleaner way

LiveData is meant to be used to contain a property value of a view

---

In ViewModel

public class TicketViewModel extends AndroidViewModel implements IServiceResponse {

    private MutableLiveData showLoadingAnimationLiveData = new MutableLiveData();

    public LiveData getShowLoadingAnimationLiveData(){
        return showLoadingAnimationLiveData;
    }

    public void addTicket(String id){

        JsonObject jsonObject= new JsonObject();
        jsonObject.addProperty("id",  id);

        NetworkUtility networkUtility= new NetworkUtility(this, ADD_TICKET);
        networkUtility.hitService(URL, jsonObject, RequestMethods.POST);
        showLoadingAnimationLiveData.setValue(true);
    }


    @Override
    public void onServiceResponse(String response, String callType){
        if(serviceTag.equalsIgnoreCase(ADD_TICKET)){    
            showLoadingAnimationLiveData.setValue(false);
        }
    }

}

---

In 'onCreate' of your Activity/Fragment

ticketViewModel.getShowLoadingAnimationLiveData().observe(this,showLoadingAnimation->{
    if(showLoadingAnimation != null && showLoadingAnimation){
        startLoadingAnimation();
    }else{
        dismissLoadingAnimation();
    }
})

---

The main concept is to divide the responsibilities, Activity/Fragment doesn't need to know which process is going on, they only need to know what are the current properties/state of there child views.

We need to maintain a LiveData in ViewModels for each changing property/state depending on Views. ViewModel needs to handle the view states depending on whats happening.

Only responsibility the Activity/Fragment has about a process is to trigger it and forget and ViewModel needs handle everything(like informing Repositories to do the work and changing View Properties).

In your Case, 'addTicket' is a process about which Activity/Fragment doesn't need to know about there status. The only responsibility of Activity/Fragment about that process is to trigger it.

ViewModel is one who needs to analyze the state of process(in-progress/success/failed) and give appropriate values to the LiveDatas to inform the respective Views