Wiring up the UI with the Kotlin code (part 1)

To achieve an interactive app, we will do the following three things:

1. We will call setContentView from the onCreate function to show the progress of our UI when we run the app.

2. We will write two more functions of our own and each one will call setContentView on a different layout (that we have yet to design).

3. Then, later in this chapter, when we design two more UI layouts, we will be able to load them at the click of a button.

As we will be building a ConstraintLayout and a TableLayout, we will call our new functions, loadConstraintLayout and loadTableLayout, respectively.

Let's do that now, and then we'll see how we can add some buttons that call these functions alongside some neatly formatted text.

Inside the onCreate function, add the following highlighted code:

override fun onCreate(savedInstanceState: Bundle?) {
   super.onCreate(savedInstanceState)

       setContentView(R.layout.main_menu)
}

The code uses the setContentView function to load...