How do I use MainActivity to trigger this MainViewModel to run?

Do you mean constructor invocation? Did you instantiate it in

MainActivity

using e.g.

ViewModelProviders

factory?

On the MainActivity you will create a variable for your viewmodel e.g

private lateinit var viewmodel

within the

onCreate()

method you will instantiate the viewmodel in the following format

viewmodel = ViewModelProviders.of(this, factory).get(MainViewModel::class.java)

,

factory

represent the factory for you view model. But you can also do it the following way if you are using new android version:

private val viewModel by viewModels<MainViewModel> { factory }