Same Instance of an arrayAdapter in Two ListView doesnot work

Question

I have two fragments in my Activity. Both of these fragments have unique listView, these fragments have methods that get values from database, One fragment shows used data and the other shows added data so I use the same Model. Also these fragments use two diffrence instance of the same arrayAdapter class which extends ArrayAdapter<>.

Class FragmentPartTaken extends Fragment

 //Instance Variables
 ListView listPartTaken;
 AdapterPartsIntakenOutMinimized adapter;
 private ArrayList<ModelPartIntakenOuttake> modelPartOuttakes;
 //onCreateView 
 listPartTaken = view.findViewById(R.id.list_part_taken);
 modelPartOuttakes = new ArrayList<>();
 adapter = new AdapterPartsIntakenOutMinimized(modelPartOuttakes,getContext());

Class FragmentPartAdded extends Fragment

 //Instance Variables
 ListView listPartAdded;
 AdapterPartsIntakenOutMinimized adapter;
 private ArrayList<ModelPartIntakenOuttake> modelPartAdded;
 //onCreateView
 listPartAdded = view.findViewById(R.id.list_part_added);
 modelPartAdded = new ArrayList<>();
 adapter = new AdapterPartsIntakenOutMinimized(modelPartAdded,getContext());

When the Activity is Launched, the list in the first Fragment selected(Displayed) is the one that is populated with data, and the other list is left blanks. If I change the order of position of these Fragments it does the same, the list in the first fragment get populated but not the second.

The arrayAdapter Override a single public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {} method. My question is do I need to have each Fragment with its own Adapter class and Model. So as all can be populated at once when the activity is launched.

Edit:

public class AdapterPartsIntakenOut extends ArrayAdapter<ModelPartIntakenOuttake> {
private ArrayList<ModelPartIntakenOuttake> dataSet;
Context mContext;
public AdapterPartsIntakenOut(ArrayList<ModelPartIntakenOuttake> data, Context context) {
 super(context, R.layout.raw_intake_outake_parts, data);
 this.dataSet = data;
 this.mContext=context;
}
private static class ViewHolder {
 TextView textAction;
 TextView textDate;
}
@NonNull
@Override
public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
 ModelPartIntakenOuttake modelPartIntakenOuttake = getItem(position);
 AdapterPartsIntakenOut.ViewHolder viewHolder; // view lookup cache stored in tag
 final View result;
 if (convertView == null) {
 viewHolder = new AdapterPartsIntakenOut.ViewHolder();
 LayoutInflater inflater = LayoutInflater.from(getContext());
 convertView = inflater.inflate(R.layout.raw_intake_outake_parts, parent, false);
 viewHolder.textAction = (TextView) convertView.findViewById(R.id.txt_action_intake_outtake);
 viewHolder.textDate = convertView.findViewById(R.id.txt_date_intake_outtake);
 result=convertView;
 convertView.setTag(viewHolder);
 } else {
 viewHolder = (AdapterPartsIntakenOut.ViewHolder) convertView.getTag();
 result=convertView;
 }
 viewHolder.textAction.setText(modelPartIntakenOuttake.getActionType());
 viewHolder.textDate.setText(modelPartIntakenOuttake.getOnDate());
 return convertView;
}
}

Edit: I am using volley library to populate the adapters in both fragment

 private void getPartAdded(){
 getActivity().runOnUiThread(mRunnable);
 String partsTakenURL = "....";
 RequestQueue requestQueue = Volley.newRequestQueue(getContext());
 JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(Request.Method.GET, partsTakenURL, null,
 new Response.Listener<JSONArray>() {
 @Override
 public void onResponse(JSONArray response) {
 for (int i = 0; i < response.length(); i++) {
 try { 
 String actionType = response.getJSONObject(i).getString("action_type");
 String onDate = response.getJSONObject(i).getString("on_date");
 modelPartAdded.add(new ModelPartIntakenOuttake(actionType,onDate));
 } catch (JSONException e) {
 e.printStackTrace();
 }
 }
 adapter.notifyDataSetChanged();
 }
 }, new Response.ErrorListener() {
 @Override
 public void onErrorResponse(VolleyError error) {
 }
 });
 requestQueue.add(jsonArrayRequest);
 listPartAdded.setAdapter(adapter);
}
Runnable mRunnable = new Runnable() {
 public void run() {
 modelPartAdded.clear();
 adapter.notifyDataSetChanged();
 }

Also on another class

 private void getPartOutTaken() {
 getActivity().runOnUiThread(mRunnable);
 String partsTakenURL = "...";
 RequestQueue requestQueue = Volley.newRequestQueue(getContext());
 JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(Request.Method.GET, partsTakenURL, null,
 new Response.Listener<JSONArray>() {
 @Override
 public void onResponse(JSONArray response) {
 for (int i = 0; i < response.length(); i++) {
 try {
 String actionType = response.getJSONObject(i).getString("action_type"); 
 String onDate = response.getJSONObject(i).getString("on_date");
 modelPartOuttakes.add(new ModelPartIntakenOuttake(actionType,onDate));
 } catch (JSONException e) {
 e.printStackTrace();
 }
 }
 adapter.notifyDataSetChanged();
 }
 }, new Response.ErrorListener() {
 @Override
 public void onErrorResponse(VolleyError error) {
 }
 });
 requestQueue.add(jsonArrayRequest);
 listPartTaken.setAdapter(adapter);
}
Runnable mRunnable = new Runnable() {
 public void run() {
 modelPartOuttakes.clear();
 adapter.notifyDataSetChanged();
 }
};;

• dominicoder: You left out the key piece of code - the adapter logic that actually loads data.
• Gabriel Rogath: @dominicoder just added the adapter class.Thanks
• dominicoder: You still haven't shown what actually adds elements to the adapter. Your sample creates two empty ArrayLists to populate each adapter. Where do you actually add items to the adapters?
• Gabriel Rogath: @dominicoder, I have just added methods that populate both adapter with volley Library
• dominicoder: I don't see anything immediately obvious from your posted code, but it's also very difficult to get a full sense of what is happening with so many snippets out of context. Debug your code and try to narrow down the issue: developer.android.com/studio/debug

Answer 1

You can use the same adapter and model class again and again. You are probably doing something wrong while populating your array lists.

• Community: Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.