异步任务中进度对话框出现异常。

Question

我正在开发一款Android应用程序，其中我使用了异步任务。在post execute方法中，当我关闭进度对话框时，会出现一个异常，并且应用程序会强制关闭。

异常信息如下：

    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)

代码如下：

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();
  }
}

日志输出：

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)

- Bansal_Sneha

---

请发布logcat输出？ - Analizer

“dialog”对象在哪里实例化？是在show_PDialog(MainActivity.this)内部吗？ - Ramprasad

@Analizer，我按照您的要求做了，令人惊讶的是这次没有出现异常，进度条也消失了。首先非常感谢您，能否告诉我原因是什么...为什么会这样？ - Sneha Bansal

@Ram 是的，show_PDialog(MainActivity.this)在onPreExecute()中被调用。 - Sneha Bansal

@分析器进度对话框出现在设备屏幕上...它没有消失。 - Sneha Bansal

Answer 1

可能当任务结束并在其onPostExecute上运行时，创建它的活动（并从中获取上下文）已经在到达onPostExecute时被销毁了。您可以保留它，或者在某个地方创建一个progressDialog实例，每次需要对话框时都可以使用，在activity的onDestroy()方法中取消它（以防发生此类情况）。

- Analizer