android.view.WindowManager$BadTokenException: Unable to add window -- token nul

原博客地址：http://aijiawang-126-com.javaeye.com/blog/662336

在Activity中newSpinner是我把mContext传入，但是出了android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application这个错误，参考了达人的文章终于搞定。

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1. private?Context?mcontext;??
2. ????@Override??
3. ????protected?void?onCreate(Bundle?savedInstanceState)?{mcontext?=?getApplicationContext();??
4. ????????System.out.println("mcontext="?+?mcontext);??
5. ????}??

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1. new?AlertDialog.Builder(mcontext)??
2. ????????????.setIcon(android.R.drawable.ic_dialog_alert)??
3. ????????????.setTitle("Warnning")??
4. ????????????.setMessage(??
5. ????????????????????"You?forget?to?write?the?message.?Do?you?want?to?fill?out?it???")??
6. ????????????.setPositiveButton("Yes",?positiveListener).setNegativeButton(??
7. ????????????????????"No",?negativeListener).create().show();??

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导致报这个错是在于new AlertDialog.Builder(mcontext)，虽然这里的参数是AlertDialog.Builder(Context context)但我们不能使用getApplicationContext()获得的Context,而必须使用Activity,因为只有一个Activity才能添加一个窗体。?

解决方法：将new AlertDialog.Builder(Context context)中的参数用Activity.this（Activity是你的Activity的名称）来填充就可以正确的创建一个Dialog了。

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1. new?AlertDialog.Builder(MyActivity.this)??
2. ????????????????.setIcon(android.R.drawable.ic_dialog_alert)??
3. ????????????????.setTitle("Warnning")??
4. ????????????????.setMessage(??
5. ????????????????????????"You?forget?to?write?the?message.?Do?you?want?to?fill?out?it???")??
6. ????????????????.setPositiveButton("Yes",?positiveListener).setNegativeButton(??
7. ????????????????????????"No",?negativeListener).create().show(); ?

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