Shared Mutable State and Concurrency. Since your function maybeWriteMessage has a default value of null for message and you are calling maybeWriteMessage() without specifying message - the default value (null) will be used when calling writeMessage(message!!). FragmentManager throws IllegalArgumentException in Kotlin, Android library written in Kotlin, provide support for Java apps. fun getName() : String = null // tries to return null, won’t compile. Hey, there, in this lesson we will be learning about one of the most important key points of Kotlin, that is the nullability. Before we understand the use of exceptions in Kotlin, let’s have a look at broad classification of exception that were there in Java: Checked Exceptions; Unchecked Exceptions ; Exceptions which are basically checked at the time of compilation are termed as Checked Exceptions. This difference is really only possible because nullability is built into the type system of Kotlin. Kotlin Null Safety. How kotlin handles the developer's pain “The NPE , Null pointer Exception — null pointer is a runtime exception. 2. In Kotlin, the type system distinguishes between references that can hold null (nullable references) and those that can not (non-null references). Type-Safe Builders. If you didn’t provide a value for a class member, it was initialized with null. Evite null pointer exception nos seus aplicativos android modernos. Pada tulisan ini kita belajar tentang null pada kotlin. if you dont want to throw null pointer exception when you try to access nullable reference b. val b: String? We can write b! But what it's gonna do is the compiler's already gonna see that this is invalid. "Get used to cold weather" or "get used to the cold weather"? Therefore, it is better to use Exception instead. Scala, as JetBrain points out, has a high compilation time. Select Expression ... Null Safety. Thanks for contributing an answer to Stack Overflow! What's the word for someone who takes a conceited stance in stead of their bosses in order to appear important? Scope Functions. The thing is that nullable types are no guaranty you won’t have NullPointerExceptions anymore. But even forbidding its use won’t be enough. Let's say if we use the double exclamation operator to find out the length of the variable figure, what happens? Why is this happening? Plotting polygons as separate plots using Python. Why does Kotlin forcibly throw KotlinNullPointerException even when the null reference isn't accessed? Even though the Kotlin compiler enforces null-safety at compile-time, sometimes we may need another safety measure at runtime, too. BaseColumns; CalendarContract.AttendeesColumns; CalendarContract.CalendarAlertsColumns; CalendarContract.CalendarCacheColumns; CalendarContract.CalendarColumns Tipe Nullable dan Jenis Non-Null You just need a way to avoid dealing with your variable when it’s not ready. Null pointer exception when calling a action class of page object model. The takeaway here is that null is not necessarily your only choice as a default value, and you should probably think twice before resorting to it. So here in this case, Kotlin is not actually gonna give you a null pointer exception. at com.series0ne.ApplicationKt.main(Application.kt:4). Adrian says: December 19, 2020 at 1:40 pm The third option is for NPE-lovers: the not-null assertion operator Why null pointer exception appear when start bound service android. Code clarity is paramount in that case. The way to do it is up to you. To throw an exception object, use the throw-expression: To catch an exception, use the try-expression: There may be zero or more catch blocks. I've worked with a number of JVM languages in production (Java, Groovy, Scala, and for the last seven years Clojure) but I haven't tried Kotlin yet.Nearly all of the talk I've seen about Kotlin focuses on how it helps you avoid the dreaded NPE by introducing the idea of nullable and non-nullable versions of types and requiring explicit handling of null when "converting" between the two. Nulls in kotlin. Kotlin is Open Source and it costs nothing to adopt. Select Expression ... Null Safety. 3.1 Goodbye Null Pointer Exception. you're asserting that the nullable parameter message is not null by using !! Null Safe. You could even choose to use some sealed class to differentiate between a populated object and a placeholder or empty one (see Refactoring, by Martin Fowler: “Introduce Null object”). Type-Safe Builders. So it's unsafe to call any method or property on this object. Evite null pointer exception nos seus aplicativos android modernos. !.length Thus, if you want an NPE, you can have it, but you The !! Kotlin provides Safe call(?.) Comparison to Java. Serialization. Kotlin Exception Handling. In Kotlin, By default, all types of variables are non-null able (i.e. We are the very first one who creates Kotlin tutorial in Bangla. BaseColumns; CalendarContract.AttendeesColumns; CalendarContract.CalendarAlertsColumns; CalendarContract.CalendarCacheColumns; CalendarContract.CalendarColumns to a non-nullable parameter, however the parameter is never accessed. converts any value to a non-null type and When I first heard about Kotlin, it didn’t take me long to realize how wonderful the language was. If message is null though, this will throw a null pointer. Kotlin helps developers avoid Null Pointer Exceptions, the #1 cause of crashes on Google Play. Not all variables can be null, so why should one be nullable and what does it imply? Kotlin’s type system is aimed to eliminate NullPointerException’s from our code. We all know how Kotlin handles the “Billion Dollar Mistake” present in Java, improving the way we handle Null Pointer Exceptions (NPE). Kotlin provides Safe call(?.) But the Null Pointer Exception is not something we explicitly throw in our Java codes. If this seems confusing, let me give you an example: imagine an Android activity in which you decide to save a certain view, but don’t manipulate it … It allows users to assign null to any variables but while accessing an object reference having null value raises a null pointer exception which user needs to handle. I think the difference between Kotlin and Java comes down to explicitly asking for a NullPointerException on each property that you know can be null. Exception is a runtime problem which occurs in the program and leads to program termination. So if any code catches explicitly KotlinNullPointerException -- which is discouraged -- then upgrading to 1.4 will be a breaking change . Don’t forget that throw or return statements have the Nothing type, which means you could virtually affect them to any variable in your code, as in: Another option is to use the require function to check your arguments’ values and throw an IllegalArgumentException if needed: What matters most is not which option you choose, but rather how clearly you isolated the portions of your code that will be run or skipped in case of a null value. Be a bit negligent with it and you will soon realize that NullPointerExceptions still happen in Kotlin! will return a non-null value of b (e.g., a String in our example) or Comments Stack Overflow for Teams is a private, secure spot for you and Kotlin seguro com null-safe usando let e operador elvis. Tony Hoare - người khởi tạo ý tưởng về Null, gọi nó là "sai lầm tỷ đô". JVM. Put simply, sometimes storing a null value into a non-nullable variable isn’t apparent at compile-time. java, kotlin, swift, optional, null checks, null pointer exception, null safety, nullable types, null-coalescing, tutorial Opinions expressed by DZone contributors are their own. Can an Eldritch Knight use a Ruby of the War Mage? the value is null. If the @Nullable and @NotNull annotations are being used properly, both Java and Android ones, Kotlin will be able to work seamlessly with them and figure out when a variable is null and when not. We can write b! Nullability is not such a complicated science. !, and this Why is it so hard to build crewed rockets/spacecraft able to reach escape velocity? As NPEs have always been an issue, both Java and Kotlin have their own way of handling null objects, as I will show below. But it didn’t have to. So basically, what you need is to clearly mark portions of code associated with a nullability condition. Output: Geeks The message variable will be empty if str’s reference is null as in case 1. You could even guard certain variables against ever risking to receive a null value (in case some rogue Java code tried to sneak it behind your back) with a simple Elvis operator: If you can’t find any other suitable value for your objects until they’re properly initialized, then your second question should be whether you actually need that temporary value. This doesn’t mean that the view attribute will always have a value though. This calls the method if the property is not null or returns null if that property is null without throwing an NPE (null pointer exception). In this quick tutorial, we’re going to see what happens when we store a null value into a non-null data type in Kotlin. The library is properly annotated. : throw(SomeException()), val nonNullValue = nullableEntry ? Especially when you realize that Kotlin developers got you covered with a clever smartcast to simplify your syntax. All exception classes in Kotlin are descendants of the class Throwable.Every exception has a message, stack trace and an optional cause. 1. Wenn ein Objekt ohne den New-Operator erstellt wurde und versucht wird, mit der Referenzvariable Operationen durchzuführen. Until you call setContentView(), calling your variable would return null. Join Stack Overflow to learn, share knowledge, and build your career. Safe call(?.) Nulls in Kotlin don’t exist until you say otherwise. (!!) To subscribe to this RSS feed, copy and paste this URL into your RSS reader. val name: String = null // tries to assign null, won’t compile. In order to write solid code, it’s important to understand the concept of null. Exceptions, also Ausnahmen, ereignen sich oft während der Testphase. During the process, you’ll learn about the following: Nullable variables. : "", val myView: View by lazy { findViewById(R.id.my_view) }, val nonNullValue = nullableEntry ? https://kotlinlang.org/docs/reference/null-safety.html#the--operator. Kotlin - Tutorial : Tạm biệt NullPointerException - Làm việc với Null trong Kotlin Report This post has been more than 3 years since it was last updated. The possible causes of Null Pointer Exceptions (NPEs) in Koltin include Java interoperation. :), Not-null assertion operator(!!) What is the equivalent of Java static methods in Kotlin? If you are looking for learning Kotlin programming language, then this course is specially designed for you. Kotlin null safety is used to eliminate the risk of null references in the code if the Kotlin compiler finds any null argument is passed without executing any other statements. This can occur due to various reasons like invalid arithmetic operation, a reference to a null object. The safe call operator can be of some use, but it should be handled with care: if you start using it everywhere, you will end up with some very unpredictable code where some lines get executed and others don’t for no obvious reason (well, the obvious reason is that some variables were null, but which ones? value of b (e.g., a String in our example) or throw an NPE if b is You can even expand that idea to other types: an empty String is often better than a null one, and an empty list will generally do a better job than a null one (see Effective Java, by Joshua Bloch : “Item 43: Return empty arrays or collections, not nulls”). Compatibility Guide for Kotlin 1.4. Is there a reason why 午 and 年 look so similar? While exploring different possible ways to handle the NPE… So next time you declare a variable in your code, don’t rush to add that little question mark and ask yourself the important questions. assertion operator (!!) Kotlin: Null can not be a value of a non-null type String. (the not-null assertion operator). Where is the antenna in this remote control board? To learn more, see our tips on writing great answers. If you never read a certain value when it is null, you don’t risk the NullPointerException and will never need to declare it as nullable. The third option is for NPE-lovers: the not-null So already at compile-time, which is very important, Kotlin is gonna tell you that this is not valid because you have a nullable type here. Nhờ vào Kotlin, bạn sẽ làm việc trong môi trường an toàn hơn (thậm chí với cả các thư viện Java), nó sẽ giảm thiểu được những vẫn đề này. When looking at the top 1,000 apps on Google Play, it was evident apps that use Kotlin have 20% fewer crashes per user. 1.1. typealias NullPointerException = NullPointerException. will yield an NPE, as seen above. Null pointer exceptions frustrate all the android developers. Null pointer exception is thrown when an application tries to use an object or variable open class NullPointerException : RuntimeException. The trick we fell for as java coders is that null was such an easy default value for our variables. Reflection. Here is my code: class FragmentStart : Fragment() { override fun onCreateView( inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle? Eaga Trust - Information for Cash - Scam? Don’t stop at nullability though: lots of other praised concepts in Kotlin imply that you get used to a certain discipline and take on some healthier habits (immutability, open or closed inheritance, lack of checked exceptions…). ... Kotlin™ is protected under the Kotlin Foundation and licensed under the Apache 2 license. Das gilt insbesondere für die ... Wenn die Länge eines Arrays abgefragt wird, dessen Wert gleich Null ist. Making statements based on opinion; back them up with references or personal experience. Give it the attention it needs and you will soon see tangible results and improvements in your code. You will learn So you could simply replace that field with a dynamic calculation: Or use a delegate to compute that value. But since you don’t need it then, you have a few options to save you the trouble of dealing with that undesired state. But don’t fool yourself into thinking that the language itself will solve all of your problems, as if by magic. Yet that doesn’t mean that this value exists at all times. Getting NullPointerExceptions is actually as simple as using a double bang. 2. One of the most commonplace pitfalls in lots of programming languages such as Java is that gaining access to a member of a null reference can end in a null reference exception. So already at compile-time, which is very important, Kotlin is gonna tell you that this is not valid because you have a nullable type here. Nothing is a concept tied to language; in Kotlin, the closest relative is null. Exception in thread "main" kotlin.KotlinNullPointerException at Far from the perplexity I felt when I first discovered that feature in Swift five years ago, it now felt much more natural in Kotlin. In some cases, it is not possible to cast variables; therefore, it throws an exception, which is called unsafe cast. Am I really receiving FT8 signals from 12,000km on 144Mhz. Kotlin's type system is aimed at eliminating the danger of null references from code, also known as the The Billion Dollar Mistake.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. 3. Daher stellt Kotlin eine Reihe von Features zu Verfügung, die das Auftreten solcher Null Pointer Exceptions bereits zur Kompilierzeit verhindern sollen. Exception Handling and Supervision. But what it's gonna do is the compiler's already gonna see that this is invalid. Kotlin’s type system is aimed to eliminate NullPointerException’s from our code. rev 2021.1.18.38333, Stack Overflow works best with JavaScript enabled, Where developers & technologists share private knowledge with coworkers, Programming & related technical career opportunities, Recruit tech talent & build your employer brand, Reach developers & technologists worldwide, Starting from Kotlin 1.4, the exception will be, Kotlin - why do I get a KotlinNullPointerException, kotlinlang.org/docs/reference/scope-functions.html#let, https://kotlinlang.org/docs/reference/null-safety.html#the--operator, Podcast 305: What does it mean to be a “senior” software engineer. Checked Exceptions are typically set on … !, and this will return a non-null In this course, we are going to explore kotlin from basic to high level concepts. we can’t assign null values to any type of variables/objects). That way, we capture all exceptions that are subclasses of Exception, including the subclasses of RuntimeException. How can I delete a LiveData using Room and LiveData inside an Activity? That’s what will truly make your code less error prone in the end, and it could even improve your Java code too! good luck tracking down the lines that were definitely executed and the ones that fell through). unless you exactly know what you're doing. When looking at the top 1,000 apps on Google Play, it was evident apps that use Kotlin have 20% fewer crashes per user. We see Bangali are staying back in every technology. Asking for help, clarification, or responding to other answers. Checked vs Unchecked Exceptions. Custom annotation for null into Kotlin JVM. Based on your business logic, it might be obvious that whenever you will need to access a certain variable, that value will not be null. It will only work on safe cases though, namely local variables or immutable ones (a mutable class member could be altered by another thread between the moment you checked its nullity and the moment you actually use it). It’s the “try with empty catch” blocks all over again…. Kotlin is designed to be complied as fast as Java and having the features of Scala. Kotlin has saveral variations… I actually heard of a legacy project that was being migrated to Kotlin by copy-paste in IntelliJ (auto conversion) exactly to get rid of null pointer… Null pointer exception is thrown when an application tries to use an object or variable reference that has the null value in it. Join my free 2-hour training! Null pointer exception while clicking the button. operators to work on nullable types. If you never read a certain value when it is null, you don’t risk the NullPointerException and will never need to declare it as nullable. This operator is used to explicitly tell the compiler that the property is not null and if it’s null, please throw a null pointer exception (NPE) nullableVariable !!. Now we’re talking. So what do we do when it fails? This may be occure due to running out of memory space, array out of bond, condition like divided by zero. Annotations. What is Null Safety in Kotlin? Kotlin helps developers avoid Null Pointer Exceptions, the #1 cause of crashes on Google Play. Null Pointer Exception causes throws an KotlinNullPointerException if message is null. Safe call(?.) Reflection. Spring Bean Null Pointer Exception The class compares each. Storing null Values in Non-Nullable Types Can Pluto be seen with the naked eye from Neptune when Pluto and Neptune are closest? Output: Geeks The message variable will be empty if str’s reference is null as in case 1. How to solve the fragment receiving null value from activity using intent in android . As one example, after adopting Kotlin, the Google Home team saw a 33% decrease in Null Pointer Exception crashes over one year. Prerequisite IntelliJ Idea or any other IDE that supports Kotlin syntaxJVM (as Kotlin is a JVM based language) Introduction JetBrains started project Kotlin in 2011. The first presentation I witnessed made it sound quite interesting, but the minute I decided to try it out, I truly fell in love with it. Die falsche Verwendung von Null-Pointern, die zu sogenannten „Null Pointer Exceptions“ führen können, ist in vielen Programmiersprachen eine häufige Fehlerursache. :), Not-null assertion operator(!!) Tipe Nullable dan Jenis Non-Null Maximum useful resolution for scanning 35mm film. So Kotlin distinguishes between nullable and non-nullable data types, which helps catch more errors at compile time. However, after years of Java, manipulating variables that could be null at any point as if it was a natural thing, people don’t necessarily understand the paradigm shift. (null, damn it!) That’s it. Remember that in Kotlin all types are objects. Java Recently I worked with Kotlin and had to use a Java library that throw exceptions. In lots of cases, non-null values can be totally valid default values. Kotlin on the other hand offers Null safety by default. ), jika null akan throw null pointer exception. Null trong Kotlin không tồn tại trừ khi bạn nói khác, nghĩa là không có biến, theo mặc định được set là null. If you love null pointer exceptions you can have it. There's almost always a better way. This course will establish a solid foundation of Kotlin so that you will have no trouble understanding android development using Kotlin later. !-operator throws an exception when the value is null. That is, no variable, by default, can be set to null. This issue comes in the form of a Null Pointer Exception (NPE) when you're trying to use the contents of a null value. As one example, after adopting Kotlin, the Google Home team saw a 33% decrease in Null Pointer Exception crashes over one year. While exploring different possible ways … Nulls in Kotlin. TL;DR: Do not use !! Exceptions. When we’re working with Java libraries, we may find ourselves facing different situations regarding null checking. How would a theoretically perfect language work? The terrible NullPointerException (NPE in short) is the most frequent Java exception occurring in production, acording to a 2016 study. Creates during real time types of variables are non-null able ( i.e way do... Using Room and LiveData inside an Activity die falsche Verwendung von Null-Pointern, die das Auftreten solcher null exception! Since it costed billions of dollars to companies we see Bangali are staying back in every technology? ). Responding to other answers the word for someone who takes a conceited stance stead... They ’ kotlin null pointer exception just a very powerful tool to prevent them… if you understand the logic behind.! Why does Kotlin forcibly throw KotlinNullPointerException even when the value is null to high level concepts for. Programming language, null type values have always been an issue nullability is built the... The double exclamation operator developers avoid null pointer exception is not something we explicitly throw our! By using message t mean that the language was will solve all of your problems as! We have the use of custom getters or delegates the safe call.. Especially when you try to access that variable, by default, can be totally valid values. Like divided by zero for as Java and you will have no trouble android! Autoboxing arrived in Java 5, most of us never bothered to wrap in. The value is null though, this will throw an NPE stack Exchange ;... Compute that value type String und versucht wird, dessen Wert gleich null ist us never bothered to wrap in! Null pada Kotlin, the closest relative is null compute that value memory space, out! Possible because nullability is built into the type system is aimed to eliminate risk. Will solve all of your program finally block may be omitted.However at least one catch or should... Bound service android statements based on opinion ; back them up with references or personal experience very... Nullability feature and it ’ s nullability feature and it ’ s important to understand the logic behind.! A reference to a non-nullable parameter, however the parameter or not, by,! T actually need a way to do it is up to you Auftreten!, val nonNullValue = nullableEntry class Throwable.Every exception has a high compilation time weather '' or get. View initialization so the button should not be null, gọi nó là `` sai lầm đô! The safest during program execution the technique to gracefully handle such problems and continue the program leads! Or property on this object his biggest regret!! null can not be null part to sure. Should one be nullable and non-nullable data types, which is called unsafe cast setContentView ( ): String null! Use Java 8 lambdas you anyway need to move continuously to stay?... To use a delegate to compute that value, they couldn ’ crash. Exists where that condition could be violated message variable will be NullPointerException instead ( a type... Nullpointerexception ’ s best practices rigor on your precious variables class Throwable.Every exception has a,. A NPE of dollars to companies exists at all times (? )! Pain “ the NPE, null kotlin null pointer exception values have always been an issue exceptions ( NPEs ) Koltin! Basic to high level concepts bond, condition like divided by zero, a reference to a 2016.. Numbers, zero is very often a totally reasonable default value mark portions of associated. To companies NullPointerException in real time with empty catch ” blocks all over again… exception instead compile-time sometimes... Problems, as if by magic exceptions you can use safe call operator due to various reasons invalid! Null-Safety at compile-time a 2016 study do it is better to use:. Programming language, then the referent value null indicates ‘ no object.... The lines that were definitely executed and the ones that fell through ) would. Knight use a delegate to compute that value arrived in Java, and frustration... Days FREE: https: //kotlinlang.org/docs/reference/null-safety.html # the -- operator t assign values! Is aimed to eliminate the risk of occurrence of NullPointerException in Java,. Why 午 and 年 look so similar function uses the parameter or not by... Illegalargumentexception in Kotlin is to eliminate NullPointerException ’ s reference is n't available may or may not be?... Requires creating a new class and inheriting the parent class, which helps catch errors. Program and leads to program termination spot for you it is up to you the is. Parameter message is not null by using message especially when you try to access nullable b.! A conceited stance in stead of their bosses in order to appear important the. Variable when it ’ s type system is aimed to eliminate NullPointerException ’ s reference null... Wires are replaced with two wires in early telephone its use won t. Realize that NullPointerExceptions still happen in Kotlin spot for you and your app won ’ t need... Value from Activity using intent in android is thrown when an application tries to null! Throw a null value, gọi nó là `` sai lầm tỷ đô '' use the double exclamation..: operator!! capture all exceptions that are subclasses of exception, which means new functionality is accessed! Look at Kotlin ’ s no excuse for dropping double bangs on your variables... Mean that the nullable parameter message is null as in case 1 call any method or on. Here in this course, we capture all exceptions that are subclasses of RuntimeException from... Or `` get used to the cold weather '' simply, sometimes storing a null pointer exception nos seus android. His biggest regret!! see Bangali are staying back in every technology has no object ’ tangible and. On this object and build your career message variable will be NullPointerException instead ( a different type ) calling... Features zu Verfügung, die das Auftreten solcher null pointer exceptions you can use safe call operator (? )... Exception when the value is null though, this will throw a null exception! Kotlin code will fail during compile-time your class, your IDE would stub its body a! Null-Safety at compile-time, sometimes storing a null object we kotlin null pointer exception ’ t provide value... Kotlin Foundation and licensed under the Kotlin view binding takes care of the many things that me. Können, ist in vielen Programmiersprachen eine häufige Fehlerursache we capture all exceptions that are of! Could simply replace that field with a dynamic calculation: or use a Ruby of the view initialization the. Clearly mark portions of code associated with a null value from Activity using intent in.... To wrap numbers in Objects exception in thread `` main '' kotlin.KotlinNullPointerException at (. Your syntax '', val myView: view by lazy { findViewById ( )! Google Play eines Arrays abgefragt wird, mit der Referenzvariable Operationen durchzuführen anyway need to think about types. Basically, what you need to move continuously to stay alive exception classes in Kotlin don ’ t.... Optional types ( R.id.my_view ) }, val myView: view by lazy { findViewById ( R.id.my_view }! So similar already gon na see that this is invalid sometimes storing a null object by default can. Daher stellt Kotlin eine Reihe von features zu Verfügung, die zu sogenannten „ null pointer exception appear when bound... Us to avoid null pointer exceptions you can read about it here: https: //pluralsight.pxf.io/c/1291657/424552/7490 Kotlin tutorial! Ausnahmen, ereignen kotlin null pointer exception oft während der Testphase is open Source and it ’ s best practices is that was..., no variable, by default Post your Answer ”, you need is to clearly portions... Try with empty catch ” blocks all over again… you and your app won ’ actually! Falsche Verwendung von Null-Pointern, die das Auftreten solcher null pointer exception — pointer... In NullPointerException in Java, and build your career: I 'm the original poster 's professor and. ’ t mean that the view exists and your app won ’ t make the NullPointerException disappear once... Possible ways to handle those cases to program termination value of a double bang out the length the. Though, this will throw an NPE Christina Lee put it in her Google I/O talk, you to... For help, clarification, or responding to other answers the original 's... Tangible results and improvements in your class, which means new functionality is available. Avoid the so dreaded NullPointerException by properly handling optional types -operator throws an exception including. Using message an exception, why is it so huge way to do is... 'S unsafe to call any method or property on this object to move to. Go unhandled and end up in NullPointerException in real time choices include the use custom... Empty if str ’ s just too easy to get wrong com.series0ne.ApplicationKt.main ( Application.kt:4 ) that throw exceptions or null! Ereignen sich oft während der Testphase better to use exception instead stay alive necessarily! Aplicativos android modernos War Mage service, privacy policy and cookie policy to you )... Tangible results and improvements in your code frustration for developers what 's the word someone... Call any method or property on this object to learn more, see here the trick we fell for Java. Convoluted codes with erring logic call setContentView ( ), jika null akan throw pointer... Kotlin distinguishes between nullable and non-nullable data types reference to a 2016 study paste this URL into RSS... To use Java 8 lambdas you anyway need to include support library so why not give Kotlin a try the... Answer ”, you might have definitely come across the atrocities of NullPointerException it creates during real time `` ''!
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