android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an appli

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。

[java] view plain copy print ?

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

private Context mcontext; @Override protected void onCreate(Bundle savedInstanceState) {mcontext = getApplicationContext(); System.out.println("mcontext=" + mcontext); }

[java] view plain copy print ?

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(); 

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

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。

[java] view plain copy print ?

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();