CODEWITHSUNDEEP
javaandroidandroid-livedataandroid-architecture-components
user9266642
user9266642

Reputation:

Delete all liveData and Observer on Spinner selected

Scenario I have Spinner and RecyclerView. The spinner has three different options VIP Users ,New Users , High Score Users. In myViewModel,

private liveData<ArrayList<User>> userList;
public void init(int position){
switch (position){
  case 0: 
    userList = myRepo.getInstance().getVipUser();
  break;

  case 1:
  userList = myRepo.getInstance().getNewUser();
 break;

 case 2:
 userList = myRepo.getInstance().getHScoreUser();
 break;
 }}

 public LiveData<ArrayList<User>> getUserList(){return userList;}

And in myFragment,

spinner.setOnItemSelectedListener(this);

 public void onItemSelected(AdapterView<?> parent, View view, int pos,long id) {
myViewModel.getUserList().removeObserver(getViewLifeCycleOwner ());
myViewModel.init(pos);

myViewModel.getUserList().observe(getViewLifeCycleOwner(), 
 userList->{
      //Attach userList to RecyclerView
          }
 }

Everything went fine. But When I select another options on Spinner. Example when I change VIP user to High Score User, livdata observe old data too. If user1,2,3 are VIP users and user4,5 are high score users, all 5 user are displaying in High score users instead of showing user4,5 only.

So I want to delete previous data from livedata when Spinner Selection change. Is there some way to accomplish this?

Upvotes: 0

Views: 130

Answers (1)

Mariusz Brona
Mariusz Brona

Reputation: 1609

what I would use is switchMap in livedata. So basically I would have something like this:

MutableLiveData userTypeLiveData = MutableLiveData<Int>;
LiveData userLiveData = Transformations.switchMap(userTypeLiveData, userType ->

    myRepo.getInstance().getUsersByType(userType);
)

void selectUser(int userType) {
     this.userTypeLiveData.setValue(userType);
}

And I would add switch in Repository class

Upvotes: 1

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