Is there any way to have one and only one instance of each activity?

Question

I\'m finding that in my application, the user can get quite \'nested\' in the various activities that are opened while the user is using the application.

For example

Answer 1

I wanted to have only one Instance of MainActivity, but when I add:

launchMode="singleInstance"

to my manifest a white screen appears before all of my app activities, so I removed singleInstance code from manifest. I added two public static variable of my MainActivity to MainActivity Class:

public static MainActivity mainActivity_instance = null;
public static MainActivity mainActivity_OldInstance = null;

then I added the following code to onCreate():

 if(mainActivity_instance != null)//if true, it means there was an instance of mainActivity before and it had to be closed.
        mainActivity_OldInstance = mainActivity_instance;
    mainActivity_instance = this;
 if(mainActivity_OldInstance != null)
        mainActivity_OldInstance.finish();

As you see, I finished previous instance of MainActivity just as the new Instance created!