Android - Fatal Exception AsynckTask # 1

Question

Я следующий код, и я столкнулся с проблемой в задаче doInBakground этот код работал один раз, и он разбился во всех попытках запустить приложение после перезагрузки устройства

public class DBConnection extends AsyncTask<String,Void,String> { 

private Context context ; 
static JSONArray jArray = null; 
String title, location, desc, time; 

public DBConnection(Context context) { 
     this.context = context; 

    } 

public void print(String msg){ 
    Toast.makeText(this.context, msg ,Toast.LENGTH_LONG).show(); 
} 


@Override 
protected String doInBackground(String... params) { 
    // TODO Auto-generated method stub 
    try{ 
     String link="http://10.0.3.2/friendLocation.php"; 

     URL url = new URL(link); 
     URLConnection conn = url.openConnection(); 
     conn.setDoOutput(true); 

     BufferedReader reader = new BufferedReader 
       (new InputStreamReader(conn.getInputStream())); 
     StringBuilder sb = new StringBuilder(); 
     String line = null; 
     // Read Server Response 
     while((line = reader.readLine()) != null){ 
        sb.append(line); 
        break; 
       } 

      return sb.toString(); 

    }catch(Exception e){ 
     return new String("Exception: " + e.getMessage()); 
    } 
} 

@Override 
    protected void onPostExecute(String result) { 

      try{ 
       jArray = new JSONArray(result); 

       sendEvent(); 
       } 
       catch(JSONException e1){ 
       Toast.makeText(this.context, "No Data Found" ,Toast.LENGTH_LONG).show(); 
       } catch (ParseException e1) { 
      e1.printStackTrace(); 
      } 

    } 


public void sendEvent(){ 
    Intent intent = new Intent(this.context, Event.class); 
    this.context.startActivity(intent); 
} 


} 

Может ли кто-нибудь помочь? Спасибо заранее.

Трассировка стека:

03-07 13:26:39.224: D/OpenGLRenderer(1351): Enabling debug mode 0 
03-07 13:26:39.252: I/Choreographer(1351): Skipped 471 frames! The  application may be doing too much work on its main thread. 
03-07 13:26:42.256: W/dalvikvm(1351): threadid=11: thread exiting with uncaught exception (group=0xa4cdfb20) 
03-07 13:26:42.264: E/AndroidRuntime(1351): FATAL EXCEPTION: AsyncTask #1 
03-07 13:26:42.264: E/AndroidRuntime(1351): Process: com.example.calendar, PID: 1351 
03-07 13:26:42.264: E/AndroidRuntime(1351): java.lang.RuntimeException: An  error occured while executing doInBackground() 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at android.os.AsyncTask$3.done(AsyncTask.java:300) 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355) 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at java.util.concurrent.FutureTask.setException(FutureTask.java:222) 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at java.util.concurrent.FutureTask.run(FutureTask.java:242) 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231) 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at java.lang.Thread.run(Thread.java:841) 
03-07 13:26:42.264: E/AndroidRuntime(1351): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare() 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at android.os.Handler.<init>(Handler.java:200) 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at android.os.Handler.<init>(Handler.java:114) 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at android.widget.Toast$TN.<init>(Toast.java:327) 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at android.widget.Toast.<init>(Toast.java:92) 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at android.widget.Toast.makeText(Toast.java:241) 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at com.example.calendar.DBConnection.print(DBConnection.java:29) 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at com.example.calendar.DBConnection.doInBackground(DBConnection.java:34) 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at com.example.calendar.DBConnection.doInBackground(DBConnection.java:1) 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at android.os.AsyncTask$2.call(AsyncTask.java:288) 
03-07 13:26:42.264: E/AndroidRuntime(1351):  at  java.util.concurrent.FutureTask.run(FutureTask.java:237) 
    03-07 13:26:42.264: E/AndroidRuntime(1351):  ... 4 more 

Answer 1

Вы не можете показать Toast из фонового потока. Удалите Toast из вашего метода print(). Если вы используете этот Toast для целей отладки, подумайте о переходе на класс Log для регистрации событий в LogCat или с использованием контрольных точек в вашей среде IDE.