nullじゃなかったら、その値を使って、そうじゃなかったらnullにままでいい、というようなケースです。kotlinのif ~ elseは値を返すので三項演算子的に書けますが、letを使った方がスッキリします。 This solution by Jayson Minard seems to have little overheads, but need to create multiple extensions to support different number of … Access 7000+ courses for 60 days FREE: https://pluralsight.pxf.io/c/1291657/424552/7490 Kotlin Beginners tutorial. One special collection of relevant functions can be described as "scope functions" and they are part of the Kotlin standard library: let, run, also, apply and with. Functions in Kotlin are very important and it's much fun() to use them. but before figuring out the difference among both, let… Let’s focus on one of these functions,let, in order to write safer code and less boilerplate. Thought there won’t be null crashes if you are not using !! Let’s look at the different ways how we can handle null references safely in Kotlin. There’s no point in optimizing code when comparing to null explicitly. There are still few techniques for using or accessing the nullable variable. and another one is null check !! With Kotlin’s null system, the value is either present, or null, so there’s nothing to unwrap. So, in Kotlin, a normal property can’t hold a null value. Java types which have these nullability annotations are represented as actual nullable or non-null Kotlin types instead of platform types. This means that Kotlin’s equivalent for flatMap() and map() are similar. Si es null evitaremos una excepción. Notice that you have to go out of your way to throw a NullPointerException in Kotlin - otherwise, the third example below would have just returned a null. a == null will be automatically translated to a === null as null is a reference and at the end, it will a reference check. Dealing with optionals. Nullかもしれない値の三項演算的なこと. Reference: Kotlin docs Kotlin has some really cool extension functions as part of the Standard library. on Kotlin? You probably already heard about them and it's also likely that you even used some of them yet. Fortunately, Kotlin has a syntax for “safe calls” – this syntax allows programmers to execute an action only when the specific reference holds a non-null value.. Let’s define two data classes to illustrate this feature: As there is no constructor as String(“”) in Kotlin, all string comparison will give true if the content will be equal. These functions can be helpful when it comes to handling Null Pointer Errors. Nullability and Collections. Working With Nullable Types Null Check. Kotlin’s collection API is built on top of Java’s collection API but it fully supports nullability on Collections. So let’s start with some normal java-esque looking null check code. De forma general en Kotlin usaremos let para hacer algo con un objeto en el caso de que éste no sea null. Solution 4. Coping with Kotlin's Scope Functions. 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