Android ListView not Populating in fragment

Question

I am trying to query parse for every entry in a Class and add it to an array list to display on a ListView. I am attempting to do this on a fragment. But I am not getting any items showing in the list, in the log I can see 4 items have been retrieved which is correct, but they are not displaying. Any suggestions I am using the following code:

 import android.os.Bundle;
 import android.support.v4.app.Fragment;
 import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ArrayAdapter;
 import android.widget.ListView;

 import com.parse.FindCallback;
 import com.parse.ParseException;
 import com.parse.ParseObject;
 import com.parse.ParseQuery;

 import java.util.ArrayList;
 import java.util.List;


  /**
   * A simple {@link Fragment} subclass.
  */
 public class InventoryDisplayFragment extends Fragment {

ArrayList<String> inventoryItems;
ArrayAdapter arrayAdapter;

public InventoryDisplayFragment() {
    // Required empty public constructor


}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

     inventoryItems = new ArrayList<String>();
    arrayAdapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, inventoryItems);

    final View rootView = inflater.inflate(R.layout.fragment_inventory_display, container, false);
    final ListView productsList = (ListView) rootView.findViewById(R.id.itemlistView);

    ParseQuery<ParseObject> query = ParseQuery.getQuery("Inventory");
    query.findInBackground(new FindCallback<ParseObject>() {
        @Override
        public void done(List<ParseObject> stockItemList, ParseException e) {
            if(e == null){
                if(stockItemList.size() > 0){



                    for(ParseObject unit : stockItemList){

                    inventoryItems.add(unit.get("productName").toString());
                        Log.d("unit", "retrieved: " + stockItemList.size());

                    }


                    productsList.setAdapter(arrayAdapter);

                }

            } else {

                Log.d("unit", "Error: " + e.getMessage());
            }
        }
    });


    // Inflate the layout for this fragment
    return inflater.inflate(R.layout.fragment_inventory_display, container, false);



}

}

Answer 1

Actually you need to return the rootView, you are inflating the view again and returning it, so it is not visible.

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

 inventoryItems = new ArrayList<String>();
arrayAdapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, inventoryItems);

final View rootView = inflater.inflate(R.layout.fragment_inventory_display, container, false);
final ListView productsList = (ListView) rootView.findViewById(R.id.itemlistView);

ParseQuery<ParseObject> query = ParseQuery.getQuery("Inventory");
query.findInBackground(new FindCallback<ParseObject>() {
    @Override
    public void done(List<ParseObject> stockItemList, ParseException e) {
        if(e == null){
            if(stockItemList.size() > 0){



                for(ParseObject unit : stockItemList){

                inventoryItems.add(unit.get("productName").toString());
                    Log.d("unit", "retrieved: " + stockItemList.size());

                }


                productsList.setAdapter(arrayAdapter);

            }

        } else {

            Log.d("unit", "Error: " + e.getMessage());
        }
    }
});


// Inflate the layout for this fragment
return rootview;

}

Answer 2

You are trying to display things on a ListView that might have not been inflated yet. If the call to Parse is faster than inflation you will potentially see a NullPointerException . Move the Parse code to onViewCreated() .

Also, you are passing an empty List to the ArrayAdapter and then you are adding items to the List . You need to call notifyDatasetChanged() .

Answer 3

why are you inflating your view again just return rootVIew in your oncreate method. Also you may instantiate adapter

for(ParseObject unit : stockItemList){
   inventoryItems.add(unit.get("productName").toString());
   Log.d("unit", "retrieved: " + stockItemList.size());
}
arrayAdapter = new ArrayAdapter<String>(getActivity(), 
    android.R.layout.simple_list_item_1, inventoryItems);

handler.postAtFrontofQueue(new Runnable(){
    productsList.setAdapter(arrayAdapter);
});

where in instantiating handler in your oncreate method.

handler = new Handler()

Answer 4

Try setting the adapter on main thread .

  getActivity().runOnUiThread (new Runnable .... etc )

do a notifyDataSetChanged() can also work .