我是android新手，我在AsyncTask中获取JSON格式的数据，我有一些TextView和RadioButton。我在AsyncTask中获得的数据我希望TextView显示相同的数据。在doInBackground（）方法中我正确地获取数据，但是当我在postExecute（）中访问数据时，我没有获取数据。
这是我的代码。 请帮助我..
String que,ans1, ans2, ans3, ans4, ans5, correct_ans, explainat;
在AsyncTask中
private class NetCheck extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
nDialog = new ProgressDialog(SectionTestActivity.this);
nDialog.setMessage("Loading..");
nDialog.setTitle("Please Wait");
nDialog.setIndeterminate(false);
nDialog.setCancelable(true);
nDialog.show();
}
@Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
Log.e("Post exec calleld", "dfds");
nDialog.dismiss();
Log.e("Post Exeec Ques",""+que);
sectionName.setText("" + section_category);
question.setText("" + que.toString());
rb_1.setText("" + ans1.toString());
rb_2.setText("" + ans2);
rb_3.setText("" + ans3);
rb_4.setText("" + ans4);
rb_5.setText("" + ans5);
}
@Override
protected Void doInBackground(Void... params) {
// TODO Auto-generated method stub
try {
cd = new ConnectionDetector(getApplicationContext());
if (!cd.isConnectingToInternet()) {
Handler handler = new Handler(Looper.getMainLooper());
handler.post(
new Runnable() {
@Override
public void run() {
AlertDialog alertDialog = new AlertDialog.Builder(
SectionTestActivity.this).create();
alertDialog.setMessage("Error connecting to internet.");
alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
}
});
alertDialog.show();
}
}
);
}
HttpClient httpClient = new DefaultHttpClient();
HttpPost httpRequest = new HttpPost(
"http://url");
httpRequest.setHeader("Content-Type", "application/json");
SharedPreferences preff = getSharedPreferences(
"MyPref", MODE_PRIVATE);
String userid = preff.getString("id", null);
Log.e("Student id", "" + userid);
JSONObject json = new JSONObject();
json.put("section_id", section_id);
json.put("userid", userid);
Log.e("JSON Object", json.toString());
StringEntity se = new StringEntity(json.toString());
se.setContentEncoding("UTF-8");
se.setContentType("application/json");
httpRequest.setEntity(se);
HttpResponse httpRes = httpClient.execute(httpRequest);
java.io.InputStream inputStream = httpRes.getEntity()
.getContent();
InputStreamReader inputStreamReader = new InputStreamReader(
inputStream);
BufferedReader reader = new BufferedReader(inputStreamReader);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
inputStream.close();
strServerResponse = sb.toString();
Log.e("Server Response", "" + strServerResponse.toString());
if (strServerResponse != null) {
try {
Log.e("if block execute", "df");
JSONArray arr = new JSONArray(strServerResponse);
JSONObject jsonObj = arr.getJSONObject(0);
pojo = new Pojo();
for (int i = 0; i < arr.length(); i++) {
JSONObject jobj2 = arr.getJSONObject(i);
que = jobj2.optString("title").trim();
qid = jobj2.optString("id").trim();
//qid=questionid;
ans1 = jobj2.optString("ans_a");
ans2 = jobj2.optString("ans_b");
ans3 = jobj2.optString("ans_c");
ans4 = jobj2.optString("ans_d");
ans5 = jobj2.optString("ans_e");
correct_ans = jobj2.optString("right_ans");
explainat = jobj2.optString("explanation");
Log .e("Que", ""+que);
Log .e("QueID", ""+qid);
Log .e("Ans2", ""+ans2);
Log .e("Ans3", ""+ans3);
Log .e("Ans4", ""+ans4);
Log .e("Ans5", ""+ans5);
Log .e("Ans1", ""+ans1);
Log .e("Correct anss", ""+correct_ans);
Log .e("Explll", ""+explainat);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler",
"Couldn't get any data from the url");
}
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
}
这是JSON
[{"id":"1","title":"Rahul bought a bike for Rs 24000 and sold it for 28000. What is his profit?","description":"","ans_a":"16.66%","ans_b":"20%","ans_c":"25%","ans_d":"30%","ans_e":"","right_ans":"A","explanation":"Sdcsdf sdf skdfj lsdfjlsdfj sdkjfn ;fgad"},{"rowid":93}]
我这里没有收到数据。
答案 0 :(得分：1)
如果你想在postexecute方法中获得结果，那么将doinBackground方法的返回类型更改为String，
这里添加了骨架示例..
private class NetCheck extends AsyncTask<Void, Void,String>
{
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected String doInBackground(Void... params) {
return "your result string";
}
@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
}
}
答案 1 :(得分：0)
那是因为你正在循环到数组而在第二个对象你没有Que和其他记录的params因此如果你必须从第一个对象改变中获取数据，它们将从optString返回空字符串“”
JSONObject jobj2 = arr.getJSONObject(0);而不是for循环