【发布时间】：2022-01-12 16:56:38
【问题描述】：
大家好，我在片段中遇到问题，从第二个片段更改为第三个片段后，片段中出现空指针异常：在第一次 onCreateView 上它工作正常，但是当我更改它时，我得到空指针异常。我试过 getContext(),getActivity(),requireContext() 但我总是得到这个异常。谢谢 java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法“java.lang.Object android.content.Context.getSystemService(java.lang.String)”
public class GetListaVozila extends AsyncTask<ArrayList<String>, Void, Void> {
protected void onPreExecute() {
/****** NOTE: You can call UI Element here. *****/
// progressDialog = getDialogProgressBar().show();
// progressDialog.setCancelable(false);
}
// Call after onPreExecute method
protected Void doInBackground(ArrayList<String>... urls) {
try {
System.out.println("pozvanooo1");
URL url = new URL("http://example/app/lista_vozila_novo.php");
URLConnection conn = url.openConnection();
HttpURLConnection httpConn = (HttpURLConnection) conn;
httpConn.setAllowUserInteraction(false);
httpConn.setInstanceFollowRedirects(true);
httpConn.setRequestMethod("POST");
httpConn.setDoInput(true);
httpConn.setDoOutput(true);
Uri.Builder builder = new Uri.Builder()
.appendQueryParameter("key", key);
String query = builder.build().getEncodedQuery();
httpConn.connect();
OutputStream os = httpConn.getOutputStream();
BufferedWriter writer = new BufferedWriter(
new OutputStreamWriter(os, "UTF-8"));
writer.write(query);
writer.flush();
writer.close();
os.close();
InputStream is = httpConn.getInputStream();
parsedString = convertinputStreamToString(is);
System.out.println("pozvanooo parsedstring" + parsedString + " - " + key);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
protected void onPostExecute(Void unused) {
Gson gson = new Gson();
Type type = new TypeToken<List<PozicijaVozila>>() {
}.getType();
listaVozila = gson.fromJson(parsedString, type);
values = new ArrayList<String>();
// ArrayList<PozicijaVozila> array_sort = new ArrayList<PozicijaVozila>(listaVozila);
for (PozicijaVozila p : listaVozila) {
values.add(p.getIme());
}
it = new ArrayList<PozicijaVozila>(listaVozila);
// for (int i = 0; i < it.size(); i++) {
// values.add(it.get(i).getIme());
// }
I got exception here: adapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_activated_1, android.R.id.text1, values);
editTextNaziv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
final Dialog dialog = new Dialog(requireContext());
dialog.setContentView(R.layout.vozila_listview);
dialog.setTitle(requireContext().getResources().getString(R.string.izaberite_vozilo));
listView = (ListView) dialog.findViewById(R.id.list);
dialog.show();
adapter.notifyDataSetChanged();
listView.setAdapter(adapter);
listView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
listView.setItemChecked(selectedIndex, false);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
int itemPosition = position;
selectedIndex = position;
String itemValue = (String) listView
.getItemAtPosition(position);
currentSelectedView = view;
editTextNaziv.setText(itemValue);
// Show Alert
view.setBackgroundColor(Color.parseColor("#F8C304"));
dialog.cancel();
}
});
}
});
// progressDialog.dismiss();
// if (selectedIndex == 0 && values.size() > 0) {
// editTextNaziv.setText(values.get(0));
// }
}
}
【问题讨论】：
标签： android