List data from an android API

arrayList.add((Coins) lCoins);

generating the following exception:

java.lang.RuntimeException: An error occured while executing doInBackground()

Until this line lCoins = new Gson().fromJson(resposta.toString(), new TypeToken<List<Coins>>(){}.getType() ); the data is recovered perfectly, however when trying to play it in the list for the user the error is presented. Below the classes in question

public class MainActivity extends AppCompatActivity {
//ATRIBUTOS
private ArrayAdapter adapter;
private ListView listView;
private ArrayList<Coins> arrayList;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //********* CONFIGURANDO A LISTAGEM DAS MOEDAS **********/
    listView = (ListView) findViewById(R.id.lv_coins);

    arrayList = new ArrayList<>();
    adapter = new CoinsAdapter(MainActivity.this, arrayList);
    listView.setAdapter(adapter);

    //********* FIM CONFIGURANDO A LISTAGEM DAS MOEDAS **********/
}

@Override
protected void onStart() {
    super.onStart();
    try{
        Coins coins = new HTTPService(arrayList)
                .execute()
                .get();

    } catch (InterruptedException e) {
        e.printStackTrace();
    } catch (ExecutionException e) {
        e.printStackTrace();
    }
}
}

Adapter:

public class CoinsAdapter extends ArrayAdapter<Coins> {
//ATRIBUTOS
private Context context;
private ArrayList<Coins> arrayList;

public CoinsAdapter(@NonNull Context c, ArrayList<Coins> objects) {
    super(c, 0,objects);
    this.context = c;
    this.arrayList = objects;

}

@NonNull
@Override
public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
    View view = null;

    //VALIDANDO E CRIANDO A LISTA DE MOEDAS
    if (arrayList != null){
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(context.LAYOUT_INFLATER_SERVICE);

        //montando a view a partir do xml
        view = inflater.inflate(R.layout.list_main, parent, false);

        //RECUPERANDO OS COMPONENTES PARA EXIBICAO
        TextView tvRank = view.findViewById(R.id.tv_rank);
        TextView tvCoin = view.findViewById(R.id.tv_coin);
        TextView tvPreco = view.findViewById(R.id.tv_preco);
        TextView tvMarket = view.findViewById(R.id.tv_market);
        TextView tvVol = view.findViewById(R.id.tv_vol);
        TextView tv1hr = view.findViewById(R.id.tv_1h);
        TextView tv24hr = view.findViewById(R.id.tv_24h);
        TextView tv7d = view.findViewById(R.id.tv_7d);

        //GRAVANDO OS DADOS DE ACORDOD COM A CLASSE MODELO
        Coins coins = arrayList.get(position);
        tvRank.setText(coins.getRank());
        tvCoin.setText(coins.getName());
        tvPreco.setText(coins.getPrice_usd());
        tvMarket.setText(coins.getMarket_cap_usd());
        tvVol.setText(coins.getVolume_usd_24h());
        tv1hr.setText(coins.getPercent_change_1h());
        tv24hr.setText(coins.getPercent_change_24h());
        tv7d.setText(coins.getPercent_change_7d());

    }
    return view;
}
}

the class that requests with webservice:

public class HTTPService extends AsyncTask<Void, Void, Coins> {
//ATRIBUTOS
private ArrayAdapter adapter;
private ListView listView;
private List<Coins>  lCoins;
private ArrayList<Coins> arrayList;

public HTTPService(ArrayList<Coins> coins) {
    this.arrayList = coins;

}


@Override
protected Coins doInBackground(Void... voids) {
    StringBuilder resposta = new StringBuilder();

    try{
        //URL QUE SERÁ CONSUMIDA
        URL url = new URL("https://api.coinmarketcap.com/v1/ticker/?limit=10");

        //---- ABRINDO A CONEXÃO ---
        HttpURLConnection conexao = (HttpURLConnection) url.openConnection();
        conexao.setRequestMethod("GET");
        conexao.setRequestProperty("Content-type","application/json");
        conexao.setRequestProperty("Accept", "application/json");
        conexao.setDoOutput(true);
        conexao.setConnectTimeout(5000);
        conexao.connect();

        //----- LENDO AS INFORMAÇÕES -------
        Scanner scanner = new Scanner(url.openStream());
        arrayList.clear();

        while (scanner.hasNext()){
            resposta.append(scanner.next());
        }

    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

            //CONVERTENDO O RETORNO PARA A CLASSE MODELO
    lCoins = new Gson().fromJson(resposta.toString(), new TypeToken<List<Coins>>(){}.getType() );
    //arrayList.add((Coins) lCoins);

    return lCoins.size() > 0 ? lCoins.get(0) : null;

}

@Override
protected void onPostExecute(Coins coins) {
    super.onPostExecute(coins);

    for (int i = 0; i <= lCoins.size(); i++){
        arrayList.add(lCoins.get(i));
    }
}

@Override
protected void onProgressUpdate(Void... values) {
    super.onProgressUpdate(values);
}

}

I made some changes and it worked, first I changed the return using the example that you had suggested to me in a previous post: return lCoins.size() > 0 ? lCoins.get(0) : null; I then put the for to retrieve the result and list line by line in onpostexecute and it worked! Many thanks!