Android(安卓)后台线程弹对话框导致程序崩溃(is not valid; is your activity running)

异常：android.view.WindowManager$BadTokenException: Unable to add window — token android.os.BinderProxy@438e7108 is not valid; is your activity running?

因为使用了AsyncTask 异步线程在线程完成以后的onPostExecute方法里面弹出窗口。

这个时候如果用户在onPostExecute调用之间按了返回按钮,activity已经onDestory了，
那么就会报出android.view.WindowManager$BadTokenException: Unable to add window -- token android.os.BinderProxy@4479b390 is not valid; is your activity running?

解决方法一在弹出窗口之前用Activity的isFinishing判断一下Activity是否还存在:

protected void onPostExecute(Object result) {       if (!isFinishing()) {           showDialog(MY_DIALOG_ID);       }   }

解决方法二在show的时候捕获一下异常

以下是测试验证
运行这个小程序默数4的时候按返回如果不加异常捕获或者判断isFinish的话会崩溃。

public class DialogTestActivity extends Activity {       @Override      public void onCreate(Bundle savedInstanceState) {           super.onCreate(savedInstanceState);           setContentView(R.layout.main);           new Task().execute();         }         private class Task extends AsyncTask<Void, Void, Void> {             @Override          protected Void doInBackground(Void... params) {               try {                   Thread.sleep(5000);               } catch (InterruptedException e) {                   e.printStackTrace();               }               return null;           }             @Override          protected void onPostExecute(Void result) {               super.onPostExecute(result);               //if (!isFinishing()) {                   //try {                       createAlertDialog().show();                   //} catch (Exception e) {                   //}               //}           }         }         private AlertDialog createAlertDialog() {           return new AlertDialog.Builder(DialogTestActivity.this).setTitle("fadfasdf")                   .setPositiveButton("OK", new DialogInterface.OnClickListener() {                       public void onClick(DialogInterface dialog, int whichButton) {                         }                   }).setNegativeButton("Cancel", new DialogInterface.OnClickListener() {                       public void onClick(DialogInterface dialog, int whichButton) {                         }                   }).create();       }   }

转自:http://dingbuoyi.iteye.com/blog/1555030#comments

更多:http://dimitar.me/android-displaying-dialogs-from-background-threads/

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