Error while receiving json from Android Studio objects

Question

Good afternoon guys, I’m having trouble getting an array of objects and show in Listview on android. In case the class that is giving error is this:

public class HTTPCarregaLista extends AsyncTask<Void, Void, List<Documento>> {

private final String filial;

public HTTPCarregaLista(String filial) {
    this.filial = filial;
}

@Override
protected List<Documento> doInBackground(Void... Void) {

    List<Documento> docs = new ArrayList<Documento>();

    StringBuilder resposta = new StringBuilder();

    try {
        URL url = new URL("http://www.meuwebservice.com" + this.filial);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("GET");
        connection.setRequestProperty("Content-type", "application/json");
        connection.setRequestProperty("Accept", "application/json");
        connection.setDoOutput(true);
        connection.setConnectTimeout(5000);
        connection.connect();

        Scanner scanner = new Scanner(url.openStream());
        while(scanner.hasNext()){
            resposta.append(scanner.nextLine());
        }

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

    return Collections.singletonList(new Gson().fromJson(resposta.toString(), Documento.class));

}

In case the line:

return Collections.singletonList(new Gson().fromJson(resposta.toString(), Documento.class));

Fire this Exception Fire:

com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2 path $

My Class Document:

public class Documento implements Serializable {
private long Cd_Filial;
private String Cd_Cod_Doc;
private String Dt_Movimento;
private String Cd_Cod_Produto;
private String Cd_Localizacao;
private String Nr_Documento;
private String Qtd_Recebida;
private String Qtd_Aceita;
private String Qtd_Vendida;
private String Qtd_Perda;
private String Qtd_Devolver;
private String Qtd_Devolvida;

@Override
public String toString(){
    return "Filial: " + getCd_Filial()
            + "\nCódigo: " + getCd_Cod_Doc()
            + "\nLocalização: " + getCd_Localizacao()
            + "\nData: " + getDt_Movimento();

}

}

And this is the return of my webservice:

[
 {"Cd_Filial":"1","Dt_Movimento":"01/01/2019 00:00:00",
 "Cd_Cod_Doc":"01","Cd_Cod_Produto":"01",
 "Cd_Localizacao":"01","Nr_Documento":"01","Qtd_Recebida":"10,000",
 "Qtd_Aceita":"0,000","Qtd_Vendida":"0,000","Qtd_Perda":"0,000",
 "Qtd_Devolver":"0,000","Qtd_Devolvida":"0,000"}
]

Can anyone say what I am doing wrong or give any hint regarding the problem? I thank from now on anyone who can help.

Answer 1

Note that in the error it is telling you where the problem is, an Object is expected, but it is receiving an array in json.

Do it this way:

Gson mGson = new Gson();
mDocumento = Arrays.asList(mGson.fromJson(response.body().getAsJsonArray(), Documento[].class));