如何使用FirebaseListAdapter <String> 在服务中？

Question

I have a Service class in my app and I have to use FirebaseListAdapter<String> in it.

Here's MyService.java file:

    public class MyService extends Service {

    DatabaseReference firebaseDatabaseRef;
    String followedBy;

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();

        firebaseDatabaseRef = FirebaseDatabase.getInstance().getReferenceFromUrl("https://***-***.firebaseio.com/");

        Toast.makeText(getBaseContext(), "Service started", Toast.LENGTH_SHORT).show();

        FirebaseListAdapter<String> adapter = new FirebaseListAdapter<String>(this,
                String.class, android.R.layout.simple_expandable_list_item_1, firebaseDatabaseRef) {
            @Override
            protected void populateView(View v, String model, int position) {
                followedBy = model.substring(30);
            }
        };
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {

        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Toast.makeText(getBaseContext(), "Service stopped", Toast.LENGTH_SHORT).show();
    }
}

but it can't be compiled as I'm getting this error:

Error:(133, 47) error: no suitable constructor found for FirebaseListAdapter(MyService,Class<String>,int,DatabaseReference)
constructor FirebaseListAdapter.FirebaseListAdapter(Activity,Class<String>,int,Query) is not applicable
(argument mismatch; MyService cannot be converted to Activity)
constructor FirebaseListAdapter.FirebaseListAdapter(Activity,Class<String>,int,DatabaseReference) is not applicable
(argument mismatch; MyService cannot be converted to Activity)

What am I supposed to put in place of this in the FirebaseListAdapter<String> to compile and run my code successfully?

Please let me know.

Answer 1

Activities are the app components that provide the user interface. The documentation for Service explains:

A Service is an application component that can perform long-running operations in the background, and it does not provide a user interface

FirebaseListAdapter supports the display of data from a Firebase database. It is used in an Activity . It cannot be used in a Service . There is no need to use it in a Service , because Services have no user interface (other than an optional Notification).

Answer 2

Please provide your Firebase initialization and Query ref.

Are you using FirebaseListAdapter inside a fragment ?.

this refers to the context of the activity. If you are having the FirebaseListAdapter inside Fragment, then use getActivity() instead of this

Please check the below code I have used. In this, I have initialized the FirebaseListAdapter in Activity.

DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("users");
Query qRef = ref.orderByChild("username");
FirebaseListAdapter<User> firebaseAdapter = new FirebaseListAdapter<User>(this,User.class,R.layout.list_item,qRef) {
            @Override
            protected void populateView(View v, User model, int position) {
                Log.i("MainAct","Populating View");
                TextView textView = (TextView) v.findViewById(R.id.list_item_text);
                textView.setText(model.getUsername());

            }
        };

Answer 3

It looks like the FirebaseRecyclerAdapter doesn't require a context to initialize, so you should be able to do:

FirebaseListAdapter<String> adapter = new FirebaseListAdapter<String>(
            String.class, android.R.layout.simple_expandable_list_item_1, firebaseDatabaseRef) {
   ...

See the code .