Calling startActivity() from outside of an Activity context requires the FLAG_ACTIVITY_NEW_TASK flag. Is this really what you want?

從一個Activity中要通過intent調出另一個Activity的話，需要使用 FLAG_ACTIVITY_NEW_TASK 
否則的話，會有force close： 
03-01 18:49:37.888 E/AndroidRuntime( 2706): FATAL EXCEPTION: main 
03-01 18:49:37.888 E/AndroidRuntime( 2706): android.util.AndroidRuntimeException: Calling startActivity() from outside of an Activity  context requires the FLAG_ACTIVITY_NEW_TASK flag. Is this really what you want? 

FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS: 

如果調出的Activtivity只是一個功能片段，並沒有實際的意義，也沒有必要出現在長按Home鍵調出最近使用過的程序類表中，那麼使用FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS 

Intent intent = new Intent(this, WaitingFallBackDialog.class); 
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS); 
startActivity(intent);