Flutter: Picking a random class

first of all, I am very new to coding so I am sorry for incoming mistakes.

However, I want to code a function in Flutter, which chooses a random class. Moreover, I still want to have the possibility to influence the probability of the classes.

I already watched Tutorials about picking random strings / ints from a list etc. but this was not exactly what I was searching for.

With this thread I hope to get to know, if there is a way to code the function I mentioned above. I´d be very happy about some keywords on which I can focus while researching.

Thanks for your help!