我想從webservices解析json,但我得到了空指針異常。但是如果我在瀏覽器中點擊url,那麼我得到的結果,但在代碼中它返回null。解析JSON時獲取NullPointer異常
這裏是我的網址: - http://www.expensekeeper.in/webservice/FetchBillCall.php?userid=7
這裏是我的代碼: -
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new LongOperation().execute("");
}
private class LongOperation extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... params) {
String url = "http://www.expensekeeper.in/webservice/FetchBillCall.php?userid=7";
JSONParser jsonParser = new JSONParser();
JSONObject jsonObject = jsonParser.getJSONFromUrl(url);
try {
//JSONArray jsonArray = jsonObject.getJSONArray("");
dueDate = jsonObject.getString("duedate");
description = jsonObject.getString("description");
status = jsonObject.getString("status");
remarks = jsonObject.getString("remarks");
} catch (JSONException e) {
e.printStackTrace();
}
return "Executed";
}
@Override
protected void onPostExecute(String result) {
Toast.makeText(MainActivity.this, dueDate+description+status+remarks, Toast.LENGTH_LONG).show();
}
}
這裏是我jsonParser類: -
public JSONObject getJSONFromUrl(String str) {
HttpURLConnection conn = null;
StringBuilder jsonResults = new StringBuilder();
try {
URL url = new URL(str);
conn = (HttpURLConnection) url.openConnection();
InputStreamReader in = new InputStreamReader(conn.getInputStream());
// Load the results into a StringBuilder
int read;
char[] buff = new char[1024];
while ((read = in.read(buff)) != -1) {
jsonResults.append(buff, 0, read);
}
json = jsonResults.toString();
} catch (MalformedURLException e) {
Log.e(LOG_TAG, "Error processing Places API URL", e);
} catch (IOException e) {
Log.e(LOG_TAG, "Error connecting to Places API", e);
} finally {
if (conn != null) {
conn.disconnect();
}
}
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
return jObj;
}
這裏是我的堆棧跟蹤: -
04-10 17:15:16.425: E/AndroidRuntime(1388): Caused by: java.lang.NullPointerException
04-10 17:15:16.425: E/AndroidRuntime(1388): at com.example.jsonsample.MainActivity$LongOperation.doInBackground(MainActivity.java:40)
04-10 17:15:16.425: E/AndroidRuntime(1388): at com.example.jsonsample.MainActivity$LongOperation.doInBackground(MainActivity.java:1)
我不明白我的代碼出了什麼問題。爲什麼我從服務器獲得空值。
請給我任何參考。
在此先感謝
哪裏'(MainActivity .java:40)'指向?對'dueDate = jsonObject.getString(「duedate」);'的 – asloob 2013-04-10 17:20:11
。 – 2013-04-10 17:22:53