In Kotlin, all variables are non-nullable by default. Non-Null Reference: These references can’t hold null values.Nullable Reference: These references can hold null values.In Kotlin, the type system differentiates between two types of references: Kotlin’s comes with null safety to eliminate NullPointerException’s from our code. ("Student name (Uppercase): " + name.toUpperCase()) Įxception in thread "main" Let’s understand with simple example in Java where NullPointerException occurs: In Java this would be the equivalent of a NullPointerException or NPE. One of the most common pitfalls in many programming languages, including Java, is that accessing a member of a null reference will result in a null reference exception. Or else use safe call operator ( ?. ) like : str?.Null Safety in Kotlin is to eliminate the risk of occurrence of NullPointerException from code. Val len = if (str != null) str.length else -1 Now suppose you want to check the length of str in case of optional, to do it safely you need to typically: Str = null // This pass thru since str is declared String ? Str = null // This line gives a compilation error Here on the same lines we will discuss about how Kotlin ensures Null safety Swift also has if let and guard let statements for safely unwrapping the optionals and handle in case of nil values. Swift uses Optionals ? and Unwrapping ! the optionals. Modern languages solves this problem by having the null safety mechanisms. In Java it used to be NullPointerException (NPE). In Objective-C, you can call a method on nil objects it wont crash but it will never ever give expected result and we developers end up debugging a whole lot of our time searching out for the culprit. One of the most irritating things in programming is apps crashing due to null / nil objects.
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