android - asynctask で例外が発生する進行状況ダイアログ ボックス

Question

私は、進行状況ダイアログボックスを閉じるときに例外が発生し、アプリケーションが強制的に閉じられるときに、非同期タスクとポスト実行メソッドを使用するアンドロイドアプリケーションを開発しています。

来る例外は次のとおりです。

    04-24 09:41:54.661: E/AndroidRuntime(1727): java.lang.IllegalArgumentException: View not attached to window manager
    04-24 09:41:54.661: E/AndroidRuntime(1727):     at android.view.WindowManagerImpl.findViewLocked(WindowManagerImpl.java:355)

コード：

data_insertion = new AsyncTask<Void, Void, Void>() {
  @Override
  protected void onPreExecute() {
    // TODO Auto-generated method stub             
    CommonUtility.show_PDialog(MainActivity.this);
    super.onPreExecute();
  }
  @Override
  protected void onPostExecute(Void result) {
    // TODO Auto-generated method stub
    //setting alaram for refresh api 
    CommonUtility.close_PDialog(); //*getting exception on this line* 
    Intent setalaram = new Intent(MainActivity.this, SetAlaram.class);
    startService(setalaram);
    Intent i = new Intent(MainActivity.this, PlayListActivity.class);
    startActivity(i);
    MainActivity.this.finish();
    super.onPostExecute(result);
    finish();
  }
  @Override
  protected Void doInBackground(Void...params) {
    // TODO Auto-generated method stub
    //some code 
  }
  return null;
}
}.execute(null, null, null); 

//and here is my close method for dilogue
public static void close_PDialog() {
  if (dialog != null && dialog.isShowing()) {
    dialog.dismiss();
  }
}

ログ出力:

04-24 09:41:54.661: E/AndroidRuntime(1727): FATAL EXCEPTION: main
04-24 09:41:54.661: E/AndroidRuntime(1727): java.lang.IllegalArgumentException: View not attached to window manager
04-24 09:41:54.661: E/AndroidRuntime(1727):     at android.view.WindowManagerImpl.findViewLocked(WindowManagerImpl.java:355)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at android.view.WindowManagerImpl.removeView(WindowManagerImpl.java:200)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at android.view.Window$LocalWindowManager.removeView(Window.java:432)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at android.app.Dialog.dismissDialog(Dialog.java:278)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at android.app.Dialog.access$000(Dialog.java:71)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at android.app.Dialog$1.run(Dialog.java:111)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at android.app.Dialog.dismiss(Dialog.java:268)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at commonUtilities.CommonUtility.close_PDialog(CommonUtility.java:233)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at com.walkover.filesharing.MainActivity$1.onPostExecute(MainActivity.java:55)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at com.walkover.filesharing.MainActivity$1.onPostExecute(MainActivity.java:1)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at android.os.AsyncTask.finish(AsyncTask.java:417)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at android.os.AsyncTask.access$300(AsyncTask.java:127)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at android.os.Handler.dispatchMessage(Handler.java:99)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at android.os.Looper.loop(Looper.java:130)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at android.app.ActivityThread.main(ActivityThread.java:3683)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at java.lang.reflect.Method.invokeNative(Native Method)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at java.lang.reflect.Method.invoke(Method.java:507)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
04-24 09:41:54.661: E/AndroidRuntime(1727):     at dalvik.system.NativeStart.main(Native Method)