Is a Button a use-case and what about the activity diagramm

Lets assume the following simple program (which makes no sense but doesn’t matter)
Textfield Name
Textfield Day
button-addName, button-removeName, button-addDay, button-removeDay

so from my point of view, I have 4 use-cases each for the functionality of a button (add-name, remove name …)
This is quite clear, if my assumption is correct

But the activity diagramm is not clear for me, cause the simple straight flow will look like:

  1. (user enters name) --> (click on addName) --> (Name is shown in lostbox)
  2. (user enters day) --> (click on addDay) --> (Day is shown in listobx)
    but how do I model the problem that the user can anytime switch from the flow 1 to the flow 2?
    Cause I can have
    (enter name) -> (enter day) -> (add name) …
    (enter day) -> (enter name) -> (add name) …
    n-combinations are possible. Do you make in this case a lot of branches/decission boxes? (which makes it extreme complex) or how you visualize that a switch is always possible between the different use cases?

Thanks a lot

To clarify, use cases are often used on domain-level models so you wouldn’t write use cases for behaviour with buttons.

If I’m understanding correctly, you’re looking for concurrency in your activity diagram, which is often depicted with a bar.