Mastering High Performance with Kotlin

lateinit

Sometimes, we need to initialize properties after class initialization and don't want to create a nullable type, for instance, if we use dependency injection:

@Inject lateinit var coffee: Coffee

Dependency injection is an implementation of inversion of control. It assumes that we should pass objects of another type to methods or constructors instead of creation instances inside a class of this object. The @Inject annotation is used to identify an injectable method, constructor, or field.

It's better to use a primary constructor here, so as to avoid creating an instance without initialized properties:

class CoffeeShop @Inject constructor(val coffee: Coffee) {

But in Android, a constructor for classes, such as Activity and Service ...