I have a Listview that gets data from a BD MySql . the problem is when the table of the DB is empty and enter the activity where is the Listview , the application stops working where it is empty, some idea to implement a default text or dialogue when it is without data.
Asynctask filling the Listview
public class AsyncRefrescar extends AsyncTask<String, String, String> {
ProgressDialog pdLoading = new ProgressDialog(EnviarPregunta.this);
HttpURLConnection conn;
URL url = null;
@Override
protected void onPreExecute() {
super.onPreExecute();
pdLoading.setMessage("\tCargando preguntas...");
pdLoading.setCancelable(false);
pdLoading.show();
}
@Override
protected String doInBackground(String... params) {
try {
url = new URL("http://bdauditorio.esy.es/Verpregunta/mostrarpre.php");
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return e.toString();
}
try {
conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(READ_TIMEOUT);
conn.setConnectTimeout(CONNECTION_TIMEOUT);
conn.setRequestMethod("GET");
conn.setDoOutput(true);
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
return e1.toString();
}
try {
int response_code = conn.getResponseCode();
if (response_code == HttpURLConnection.HTTP_OK) {
InputStream input = conn.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(input));
StringBuilder result = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
result.append(line);
}
return (result.toString());
} else {
return ("unsuccessful");
}
} catch (IOException e) {
e.printStackTrace();
return e.toString();
} finally {
conn.disconnect();
}
}
@Override
protected void onPostExecute(String result) {
pdLoading.dismiss();
if (result.equals("unsuccessful")) {
final AlertDialog.Builder alertaDeError = new AlertDialog.Builder(EnviarPregunta.this);
alertaDeError.setTitle("Error");
alertaDeError.setMessage("Ups, no se han podido cargar las preguntas. Intentelo de nuevo.");
alertaDeError.setPositiveButton("Aceptar", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
alertaDeError.create();
alertaDeError.show();
} else {
//Existen Datos
List<String> preguntas = new ArrayList<String>();
//Parsea la respuesta obtenida por el Asynctask
JSONArray jsonArray = null;
try {
jsonArray = new JSONArray(result);
} catch (JSONException e) {
e.printStackTrace();
}
assert jsonArray != null;
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject preguntaDatos = null;
try {
preguntaDatos = jsonArray.getJSONObject(i);
} catch (JSONException e) {
e.printStackTrace();
}
String pregunta = null;
try {
assert preguntaDatos != null;
pregunta = preguntaDatos.getString("pregunta");
} catch (JSONException e) {
e.printStackTrace();
}
preguntas.add(pregunta);
}
//crear el Adapter.
ArrayAdapter<String> adapter = new ArrayAdapter<String>(EnviarPregunta.this,
android.R.layout.simple_list_item_1, preguntas);
//Asignas el Adapter a tu ListView para mostrar los datos.
mostrarr.setAdapter(adapter);
///
}
}
}