We know that NullPointerException occurs when we try to call a method or access a property on a variable which is null. To allow null values, you have to declare a variable as nullable by appending a question mark in its type declaration – var nullableGreeting: String? = 'Hello, World' So If you try to assign a null value to a regular variable, the compiler will throw an error – var greeting: String = 'Hello, World' That means You have the ability to declare whether a variable can hold a null value or not.īy supporting nullability in the type system, the compiler can detect possible NullPointerException errors at compile time and reduce the possibility of having them thrown at runtime.Īll variables in Kotlin are non-nullable by default. Kotlin supports nullability as part of its type System. Well, Enter Kotlin! Nullability and Nullable Types in Kotlin Wouldn’t it be nice if we could detect possible NullPointerException exception errors at compile time itself and guard against them? NullPointerExceptions are Runtime Exceptions which are thrown by the program at runtime causing application failure and system crashes. If you have been programming in Java or any other language that has the concept of null reference then you must have heard about or experienced NullPointerException in your programs.

Null safe kotlin