Converting JSON to android arraylist

Question

Good afternoon! I’m trying to consume an API on android but I’m having difficulty because in the JSON file it brings a category, I tried to add the variable "acronym" but it did not work; the JSON returned in the variable answer is this: That one "brl": {, is where I believe the information I’m not advising to put on the list!

{"brl":{"name":"Real","txWithdrawalFee":9,"MinWithdrawal":30,"txWithdrawalPercentageFee":0.0025,"minConf":1,"minDeposit":0,"txDepositFee":0,"txDepositPercentageFee":0,"minAmountTrade":1,"decimal":8,"decimal_withdrawal":8,"active":1,"dev_active":1,"under_maintenance":0,"order":"010","is_withdrawal_active":1,"is_deposit_active":1},"btc":{"name":"Bitcoin","txWithdrawalMinFee":0.0001,"txWithdrawalFee":0.0001,"MinWithdrawal":0.004,"txWithdrawalPercentageFee":0,"minConf":1,"minDeposit":0,"txDepositFee":0,"txDepositPercentageFee":0,"minAmountTrade":0.0001,"decimal":8,"decimal_withdrawal":8,"active":1,"dev_active":1,"under_maintenance":0,"order":"020","is_withdrawal_active":1,

Follow the variables of my model class:

public class Currencies {
//ATRIBUTOS
private String sigla;
private String name;
private String txWithdrawalFee; //taxa de retirada
private String txWithdrawalPercentageFee; //percentual da taxa de retirada
private String minConf;
private String minAmountTrade; //quantidade minima para trade
private String decimal;
private String active;

below comes the getter and setters methods.

And that’s the class that makes the connection

public class HTTPService extends AsyncTask<Void, Void, Currencies> {
//ATRIBUTOS
private ArrayAdapter adapter;
private ListView listView;
private Context context;
private List<Currencies> currenciesList;
private ArrayList<Currencies> currenciesArrayList;
private ProgressBar load;
private int task;
private String call;

private static final String URL_CURRENCIES = "https://braziliex.com/api/v1/public/currencies";

public HTTPService(ArrayList<Currencies> mCurrencies, Context c, int param){
    this.currenciesArrayList = mCurrencies;
    this.context = c;
    this.task = param;
}

@Override
protected Currencies doInBackground(Void... voids) {
    //reposta da chamada da API da Braziliex
    StringBuilder resposta = new StringBuilder();

    //bloco que tenta executar a chamada da API
    try{
        //verificando qual será a chamada
        switch (task){
            case 1:
                call = URL_CURRENCIES;
                break;
        }

        //fazendo a chamada da API
        URL url = new URL("https://braziliex.com/api/v1/public/currencies");

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

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

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


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

    //O ERRO ACONTECE NESSA LINHA, AO PASSAR PARA A LISTA
    currenciesList = new Gson().fromJson(resposta.toString(), new TypeToken<List<Currencies>>(){}.getType());

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

}

When executing, in the line where I marked that the error happens it presents the following exception:

Caused by: com.google.gson.Jsonsyntaxexception: java.lang.Illegalstateexception: Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column 2 path $

The return on the site of braziliex:

Thank you!

Answer 1

Is that actually the returned JSON is not a list, it is an object with 2 objects inside, btc and ltc. So instead of converting JSON into a list, you need to identify the object ltc and convert, then identify the object btc and convert also.

JSONObject respostaJsonObject = new JSONObject(resposta.toString());

JSONObject ltcJsonObject = respostaJsonObject.getJSONObject("ltc"); //Pegando apenas o  
//objeto ltc dentro do json, você pode manusear a classe JSONObject ou fazer 
//como eu fiz abaixo

Currencies ltc = new Gson().fromJson(ltcJsonObject.toString(), Currencies.class);

Currencies btc = new Gson().fromJson(
      respostaJsonObject.getJSONObject("btc").toString(),
      Currencies.class
);