Не могу решить эту ошибку LogCat, чтобы получить представление списка
Я пытаюсь получить список, отправив запрос на сервер. Для этого я использую asynctask, чтобы справиться с этим. Код выглядит так. Даже после стольких экспериментов в сети я получаю ошибки logcat следующим образом.
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.AlarmManager;
import android.app.ListActivity;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
public class AndroidJSONParsingActivity extends ListActivity {
public static String url = "http://ensignweb.com/sandbox/app/comment11.php";
// JSON Node names
protected static final String TAG_PRODUCTS = "products";
protected static final String TAG_CID = "cid";
public static final String TAG_NAME = "name";
// contacts JSONArray
JSONArray products = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
new Message().execute(url);
startService(new Intent(this, UpdateService.class));
Intent intent = new Intent(this,UpdateService.class);
PendingIntent pIntent = PendingIntent.getService(this, 0, intent, 0);
AlarmManager alarm = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
alarm.setRepeating(AlarmManager.RTC_WAKEUP, System.currentTimeMillis(), 30000, pIntent);
}
@Override
protected void onStart() {
// TODO Auto-generated method stub
super.onStart();
}
//Belongs to update service
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
// stopService(new Intent(this, UpdateService.class));
}
class Message extends AsyncTask<String, Integer, ArrayList<HashMap<String, String>> > {
ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();
@Override
protected ArrayList<HashMap<String, String>> doInBackground(String... params) {
// Creating JSON Parser instance
JSONParser jParser = new JSONParser();
// getting JSON string from URL
JSONObject json = jParser.getJSONFromUrl(params[0]);
try {
// Getting Array of Contacts
products = json.getJSONArray(TAG_PRODUCTS);
// looping through All Contacts
for(int i = products.length()-1; i >=0; i--){
JSONObject c = products.getJSONObject(i);
// Storing each json item in variable
String cid = c.getString(TAG_CID);
String name = c.getString(TAG_NAME);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_CID, cid);
map.put(TAG_NAME, name);
// adding HashList to ArrayList
mylist.add(map);
Log.d("value", mylist.toString());
}
} catch (JSONException e) {
e.printStackTrace();
}
return mylist;
}
@Override
protected void onPostExecute(ArrayList<HashMap<String, String>> result) {
ListAdapter adapter = new SimpleAdapter(AndroidJSONParsingActivity.this, result , R.layout.list_item,new String[] { TAG_NAME,}, new int[] {
R.id.name});
AndroidJSONParsingActivity.this.setListAdapter(adapter);// If Activity extends ListActivity
final ListView lv = getListView();
lv.setTextFilterEnabled(true);
}
}
}
JSONParser.java
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;
import android.util.Log;
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public JSONObject getJSONFromUrl(String url) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}
LogCat показывает это сообщение
01-11 11:46:34.331: E/Buffer Error(483): Error converting result java.io.IOException: Attempted read on closed stream.
01-11 11:46:34.331: E/JSON Parser(483): Error parsing data org.json.JSONException: End of input at character 0 of
01-11 11:46:34.331: W/dalvikvm(483): threadid=7: thread exiting with uncaught exception (group=0x4001d800)
01-11 11:46:34.342: E/AndroidRuntime(483): FATAL EXCEPTION: AsyncTask #1
01-11 11:46:34.342: E/AndroidRuntime(483): java.lang.RuntimeException: An error occured while executing doInBackground()
01-11 11:46:34.342: E/AndroidRuntime(483): at android.os.AsyncTask$3.done(AsyncTask.java:200)
01-11 11:46:34.342: E/AndroidRuntime(483): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
01-11 11:46:34.342: E/AndroidRuntime(483): at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
01-11 11:46:34.342: E/AndroidRuntime(483): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
01-11 11:46:34.342: E/AndroidRuntime(483): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
01-11 11:46:34.342: E/AndroidRuntime(483): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
01-11 11:46:34.342: E/AndroidRuntime(483): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
01-11 11:46:34.342: E/AndroidRuntime(483): at java.lang.Thread.run(Thread.java:1096)
01-11 11:46:34.342: E/AndroidRuntime(483): Caused by: java.lang.NullPointerException
01-11 11:46:34.342: E/AndroidRuntime(483): at com.androidhive.jsonparsing.AndroidJSONParsingActivity$Message.doInBackground(AndroidJSONParsingActivity.java:95)
01-11 11:46:34.342: E/AndroidRuntime(483): at com.androidhive.jsonparsing.AndroidJSONParsingActivity$Message.doInBackground(AndroidJSONParsingActivity.java:1)
01-11 11:46:34.342: E/AndroidRuntime(483): at android.os.AsyncTask$2.call(AsyncTask.java:185)
01-11 11:46:34.342: E/AndroidRuntime(483): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
01-11 11:46:34.342: E/AndroidRuntime(483): ... 4 more
log.d "строка json" показывает вот так
01-11 12:43:29.891: D/json string(629): {"success":1,"products":[{"cid":"1","name":"bernard"},{"cid":"2","name":"Vijay"},{"cid":"3","name":"vikas_admin"},{"cid":"4","name":"vikas_admin"},{"cid":"5","name":"vikas_admin"},{"cid":"6","name":"vikas_admin"},{"cid":"7","name":"Vikas B L"},{"cid":"8","name":"chanakyavikas"},{"cid":"9","name":"vikram"},{"cid":"10","name":"Vidya"},{"cid":"11","name":"bernard"},{"cid":"12","name":"Thenewone"},{"cid":"13","name":"another"},{"cid":"14","name":"1245"},{"cid":"15","name":"kljdf.d,samfas"},{"cid":"16","name":"this"},{"cid":"17","name":"l;asdkfjalskjf"},{"cid":"18","name":"just got refreshed "},{"cid":"19","name":"not working"},{"cid":"20","name":"Checking"},{"cid":"21","name":"trying again"},{"cid":"22","name":"checking after few minutes"},{"cid":"23","name":"checking after many minutes"},{"cid":"24","name":"this one after 40 mintues"},{"cid":"25","name":"Let me try it once again. Even after this, it must run"},{"cid":"26","name":"Coming to track"},{"cid":"27","name":"let me check after 40 minutes"},{"cid":"28","name":"Ok. Let me give some time"},{"cid":"29","name":"let me check after lunch"},{"cid":"30","name":"checking after more than 2 hours"},{"cid":"31","name":"Now trying without icon. Lets see how it will gonna work"},{"cid":"32","name":"mic checking"},{"cid":"33","name":"check check check"},{"cid":"34","name":"check check again"},{"cid":"35","name":"Back to work"},{"cid":"36","name":"trying long long long time after"},{"cid":"37","name":"bye byeeeeeeeeeee"},{"cid":"38","name":"how is it going"},{"cid":"39","name":"Good morning Ensign"},{"cid":"40","name":"Trying AlarmManager"},{"cid":"41","name":"alarm! alarm! alarm!"},{"cid":"42","name":"Its been more than 30minutes"},{"cid":"43","name":"Let me see in the mobile about its working"},{"cid":"44","name":"How is it going"},{"cid":"45","name":"How is it going after many hours"},{"cid":"46","name":"huga huga huga"},{"cid":"47","name":"bye bye"},{"cid":"48","name":"It is now 7.47"},{"cid":"49","name":"Good morning Ensign"},{"cid":"50","name":"Once again good morning"},{"cid":"51","name":"Inside the office"},{"cid":"52","name":"Not working again"},{"cid":"53","name":"asdlkfjalsjfdl"},{"cid":"54","name":"Trying again and again"},{"cid":"55","name":"akl;sdjf;las"},{"cid":"56","name":"alarm! alarm! alarm!"},{"cid":"57","name":"adding boot complete"},{"cid":"58","name":"We are three now"},{"cid":"59","name":"check check again again"},{"cid":"60","name":"How is working now"},{"cid":"61","name":"Date is 10\/01\/2013"},{"cid":"62","name":"Now working fine"},{"cid":"63","name":"Had a good lunch"},{"cid":"64","name":"I'm with Mr. Johan "},{"cid":"65","name":"Let me check if booting works or not."},{"cid":"66","name":"checking after rebooting"},{"cid":"67","name":"Nop! rebooting not working"}]}
3 ответа
Использование
dialog=ProgressDialog.show(AndroidJSONParsingActivity.this,
"Processing", "Please be patient");
вместо
dialog.show(getApplicationContext(), "Processing", "Please be patient");
показывать ProgressDialog от AsyncTask
Трассировка стека говорит о том, что вы пытаетесь прочитать данные из закрытого потока. Похоже, вы пытаетесь прочитать ответ из Интернета после того, как вы уже закрыли поток. Дважды проверьте это при чтении Json из Интернета.
Также вы получаете нулевой указатель. Чтобы найти их, вы должны иметь возможность проходить код построчно в отладчике (используйте условные точки останова, если в цикле for иначе было бы адски отлаживать). С первого взгляда я рискну догадаться, что это следующая строка, которая убивает тебя
products = json.getJSONArray(TAG_PRODUCTS);
Я предполагаю это, потому что, если данные не вернутся из сети, тогда объект json будет нулевым.
надеюсь, это поможет еще вопросы, дайте мне знать
Использование this вместо getApplicationContext в onPreExecute метод для отображения предупреждения