Android Development with Kotlin

Nothing return type

Sometimes we need to define a function that is always throwing exceptions (never terminating normally). Two real-life use cases are:

• Functions that simplify error throwing. This is especially useful in libraries where the error system is important and there is a need to provide more data about error occurrences. (As an example, look at the throwError function presented in this section.)
• Functions used for throwing errors in unit tests. This is useful when we need to test error handling in our code.

For these kinds of situation, there is a special class called Nothing. The Nothing class is an empty type (uninhabited type), meaning it has no instances. A function that has Nothing return type won't return anything and it ...