Kotlin is the new programming language used for the Android application development. Kotlin provides Int and Long for Integers, Double and Float for floating-point values, Boolean for Boolean values and String for textual data. Swift also provides three primary collection types, List, Set and Map.
Kotlin stores variables and uses its identifying name as reference to values. You may declare a variable with a value as read-only. A read-only variable can be assigned only once.
Kotlin introduces a nullable type when a null value is possible . Use of a nullable type means either “a value of the intended type is available” or “a null value”. Nullable types work for any type.
Kotlin is a type-safe language, which means that if your code requires a String, type safety will not allow you to pass an Int by mistake.