Intent setting the role of flag

1, Intent.flag_activity_reorder_to_front

The sign in intent indicates that if the activity has been activated, it will not generate new activity, but simply add the activity instance to the top of the stack.

New Intent (Reorderfour.  this, reordertwo. class);
Intent.addflags (Intent.flag_activity_reorder_to_front);
StartActivity (Intent);

2, Flag_activity_no_history

If set, the new activity will no longer be retained in the history stack. Once the user has left it, the activity is closed. This can also be done by setting the Nohistory attribute.

done!

Intent setting the role of flag