Android Development with Kotlin

Late-initialized properties

Sometimes, we know that a property won't be null, but it won't be initialized with the value at declaration time. Let's look at a common Android example--retrieving a reference to a layout element:

    class MainActivity : AppCompatActivity() { 
 
       private var button: Button? = null 
 
       override fun onCreate(savedInstanceState: Bundle?) { 
           super.onCreate(savedInstanceState) 
           button = findViewById(R.id.button) as Button 
       } 
    } 

The button variable can't be initialized at declaration time because the MainActivity layout is not yet initialized. We can retrieve the reference to the button defined in the layout inside the onCreate method, but to do this we need to declare a variable as nullable (Button?).

Such an approach seems quite ...