Android 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:

[java] view plain copy

1. protected void onPostExecute(Object result) {     
2.     if (!isFinishing()) {     
3.         showDialog(MY_DIALOG_ID);     
4.     }     
5. }    

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。 

[java] view plain copy

1. public class DialogTestActivity extends Activity {     
2.     @Override    
3.     public void onCreate(Bundle savedInstanceState) {     
4.         super.onCreate(savedInstanceState);     
5.         setContentView(R.layout.main);     
6.         new Task().execute();     
7.     
8.     }     
9.     
10.     private class Task extends AsyncTask<Void, Void, Void> {     
11.     
12.         @Override    
13.         protected Void doInBackground(Void... params) {     
14.             try {     
15.                 Thread.sleep(5000);     
16.             } catch (InterruptedException e) {     
17.                 e.printStackTrace();     
18.             }     
19.             return null;     
20.         }     
21.     
22.         @Override    
23.         protected void onPostExecute(Void result) {     
24.             super.onPostExecute(result);     
25.             //if (!isFinishing()) {     
26.                 //try {     
27.                     createAlertDialog().show();     
28.                 //} catch (Exception e) {     
29.                 //}     
30.             //}     
31.         }     
32.     
33.     }     
34.     
35.     private AlertDialog createAlertDialog() {     
36.         return new AlertDialog.Builder(DialogTestActivity.this).setTitle("fadfasdf")     
37.                 .setPositiveButton("OK", new DialogInterface.OnClickListener() {     
38.                     public void onClick(DialogInterface dialog, int whichButton) {     
39.     
40.                     }     
41.                 }).setNegativeButton("Cancel", new DialogInterface.OnClickListener() {     
42.                     public void onClick(DialogInterface dialog, int whichButton) {     
43.     
44.                     }     
45.                 }).create();     
46.     }     
47. }