How does android:noHistory=“true” work?

Question

Lets say I have a base activity with a menu, when I click on menu item A, it goes to activity A. I open the menu again, and go to B. From B I go back to A, and back and four

Answer 1

android:noHistory=“true” works :-

Let suppose you have opened "your app".

You are on homepage Activity now,

After it you go to the another(second) activity.Here from second activity you press the home button of mobile device or open the some other application.

Now again if you open "your app" it will go to the homepage of app instead of going to the activity which one you left the app(i.e.second activity).

Answer 2

I had few fragments in my app and it seemed difficult to get out to the home screen by pressing back button without entering Launcher Activity of my app. I used android:noHistory="true" in the manifest of the launcher Activity of my app and the problem gets solved now.

Answer 3

From the docs about noHistory:

A value of "true" means that the activity will not leave a historical trace. It will not remain in the activity stack for the task, so the user will not be able to return to it.

Regarding your question:

does the true stack of A, B, A, B, A, B exist?

The docs would indicate no.

I'm concerned with resource issues and not slowing down a users android device.

You really don't need to worry about this. The OS should handle the cleanup of activities when memory is getting low. Its more likely that poor use of bitmaps or logic in your activities will result in performance slowdowns.