How to display differents images, not created when the activity is create

I'm developing a game and i'm asking myself a question. In the model of the application, I have an endless mode so I create a number of monsters and when they die, I create new ones etc... And they move, they are no always at the same place.

I would like to know how to display them because in the activity, it will be 5 monsters but after 4, 3, 2, 1 and 0.

So I would like to display them dynamically and I don't know if it's possible.