Trouble with logic flow for filtering search method on CS50 Pokedex - cs50

Question

The app compiles fine but initially it shows nothing in the list. When I use the search bar, it doesn't display my filtered information and when I get rid of search, the entire list is finally display. Any help would be really appreciated, this is my first time ever coding in Java.
Here is my adapter code.
public class PokedexAdapter extends RecyclerView.Adapter<PokedexAdapter.PokedexViewHolder> implements Filterable {
public static class PokedexViewHolder extends RecyclerView.ViewHolder {
public LinearLayout containerView;
public TextView textView;
PokedexViewHolder(View view) {
super(view);
containerView = view.findViewById(R.id.pokedex_row);
textView = view.findViewById(R.id.pokedex_row_text_view);
containerView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Pokemon current = (Pokemon) containerView.getTag();
Intent intent = new Intent(v.getContext(), PokemonActivity.class);
intent.putExtra("name", current.getName());
intent.putExtra("url", current.getUrl());
v.getContext().startActivity(intent);
}
});
}
}
private List<Pokemon> pokemon = new ArrayList<>();
private RequestQueue requestQueue;
private List<Pokemon> filteredPokemon = new ArrayList<>();
PokedexAdapter(Context context) {
requestQueue = Volley.newRequestQueue(context);
loadPokemon();
}
public void loadPokemon() {
String url = "https://pokeapi.co/api/v2/pokemon?limit=365";
JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, url, null, new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
try {
JSONArray results = response.getJSONArray("results");
for (int i = 0; i < results.length(); i++) {
JSONObject result = results.getJSONObject(i);
String name = result.getString("name");
pokemon.add(new Pokemon(
name.substring(0, 1).toUpperCase() + name.substring(1),
result.getString("url")
));
}
notifyDataSetChanged();
} catch (JSONException e) {
Log.e("cs50", "Json error", e);
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Log.e("cs50", "Pokemon list error");
}
});
requestQueue.add(request);
}
#NonNull
#Override
public PokedexViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.pokedex_row, parent, false);
return new PokedexViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull PokedexViewHolder viewholder, int position){
Pokemon results = pokemon.get(position);
viewholder.textView.setText(results.getName());
viewholder.containerView.setTag(results);
}
#Override
public int getItemCount() {
return filteredPokemon.size();
}
#Override
public Filter getFilter() {
return new PokemonFilter();
}
private class PokemonFilter extends Filter {
#Override
protected FilterResults performFiltering(CharSequence constraint) {
// implement your search here
FilterResults results = new FilterResults();
if (constraint == null || constraint.length() == 0) {
//No filter implemented return whole list
results.values = pokemon;
results.count = pokemon.size();
}
else {
List<Pokemon> filtered = new ArrayList<>();
for (Pokemon pokemon : filtered) {
if (pokemon.getName().toUpperCase().startsWith(constraint.toString())) {
filtered.add(pokemon);
}
}
results.values = filtered;
results.count = filtered.size();
}
return results;
}
#Override
protected void publishResults(CharSequence constraint, FilterResults results) {
filteredPokemon = (List<Pokemon>) results.values;
notifyDataSetChanged();
}
}
}
I really am not sure what is going on and given my knowledge of the subject, you could really help with understanding the logic better. Please let me know if there is any other information you would like from me about the code.

Answer 1

You might have already solved it and finished the Android tracks but this was the only thing I changed and it seemed to work after that.
for (Pokemon pokemon : pokemon) {
if (pokemon.getName().toUpperCase().startsWith(constraint.toString().toUpperCase()) {
filtered.add(pokemon);
}
}