IllegalStateException:classCaptor. Other threads similar to Kotlin : cardProductItem must not be null. We'll compare them in the next section. To further aid developers Kotlin provides three convenient higher-order functions: let, run and apply. It is however considered a best practice to restrict the visibility of variables to the smallest possible scope. r/Kotlin: Discussion about Kotlin, statically typed programming language for the JVM, Android and the browser. The most common use of secondary constructor comes up when you need to extend a class that provides multiple constructors that initialize the class in different ways. In Kotlin non-null vals must be initialized. IllegalStateException throwed, just change the definition of val question: String into val question: String? and try again. Functions in Kotlin are very important and it's much fun() to use them. Try upgrading to the latest stable version. By default, property types in Kotlin cannot be null. Otherwise, it returns the same argument as a non-nullable type: val strNoNull: String = checkNotNull(str - Selection from Kotlin Quick Start Guide [Book]. IllegalArgumentException: ExecutionId must not be null I upgraded to Spring Batch 1. IllegalArgumentException: host parameter is null Java Android java. Example for Kotlin lateinit. Non-private fields. IllegalStateException: invoke() must not be null 何が悪かったか Kotlin側に渡すJavaで定義したFunction0のオブジェクトでinvoke()をoverrideした際にreturn nullしていたのが悪かった。J…. The sendData() method is written in Kotlin and the second parameter cannot be null. A collection of random and frequently used idioms in Kotlin. Suppose it was very important that the first five are never null, but the last one is nullable. Every reference can potentially be null. I learned the 😓 hard way: There should be better ways to launch the Kotlin Android activities. 0 replies setChoiceMode in GridView with custom ArrayAdapter does not work. A solution based on the same principles could be applied to Activities but there one very ugly downside. IllegalArgumentException: ExecutionId must not be null I upgraded to Spring Batch 1. Edit: Also companion objects everywhere, as some people with Java backgrounds have it so ingrained that static methods need to belong to a class. Fragment#requireContext, for example, returns a non-null Context and throws an IllegalStateException if called when a Context would be null. Null Safety. All callback methods will be called from the thread on which the browser was constructed. Kotlin's type system is aimed at eliminating the danger of null references from code, also known as the The Billion Dollar Mistake. Otherwise, it is enough to set to null the parent's corresponding child. IllegalStateException: Target host must not be null, or set in. I do not create a new String each time, that happens anyway because of readLine. Kotlin has two types of references that are interpreted by the compiler to give the programmer information about the correctness of a program at compile time - those that are nullable and those that are not. The type of the property must be non-null, and it must not be a primitive type. Initialization of that variable could be done at a later point in code. Contribute to JetBrains/kotlin development by creating an account on GitHub. A cold asynchronous data stream that sequentially emits values and completes normally or with an exception. For java developers learning kotlin should not be tough and will be easy to grab in quick time. java) must not be null. DialogFragment. I have been working on Kotlin for couple of weeks by converting the Activities of the android app I developed java to Kotlin. I learned the 😓 hard way: There should be better ways to launch the Kotlin Android activities. length } Here, we named a variable string within the block. IllegalStateException: Mockito. When running on Android 3. Non-private fields. Type aliases (added on Kotlin 1. I invite you to use the nhaarman/mockito-kotlin library, it provides workarounds for this kind of call. IllegalStateException: ??? must not be null`` ``kt kotlin. scheme=null, host=null, path=null Showing 1-15 of 15 messages. The in and out types are directives for Kotlin's type. Note: If you are using IntelliJ IDEA or any other IDE with Kotlin Plugin, you can write Kotlin code along with Java code in the same. However, a call to. Bare exceptions and errors are little help. Press J to jump to the feed. For example: kotlin checkNotNull(value) { "Value cannot be null!" } Why doesn't it take the message as a parameter instead? kotlin checkNotNull(value, message = "Value cannot be null!") Is it because the string isn't initialized until it's needed in the first example? Wouldn't inlining the second example produce the same effect?. IllegalStateException: Mockito. However, that exception should not reach into the UI layer, at least not to the point where you will have a crash. However, this computation blocks the main thread that is running the code. The attribute colors of product is a list of string. This is not true immutability. When those values are computed by an asynchronous code we can mark. IllegalStateException: dtoCaptor. We'll compare them in the next section. It's not an exhaustive guide, but it establishes a good foundation and provides an overview of the whole Kotlin type-safe DSL approach. Think we should get a crash-signature for Android Background Services :) Stripped from product change [@ java. testSettingFunction Get unlimited access to the best stories on Medium — and support writers while you. 0 and ran a test that throws a runtime exception in my item writer. So if we want to find something similar in Java, that would be the Singleton pattern. lazy is lazy initialization. Platform types are non-denotable, meaning that one can not write them down explicitly in the language. IllegalArgumentException: Environment must not be null; TopShelf [Failure] Stop must not be null; GoogleApiClient must not be null [Awareness API] Picasso IllegalArgumentException Target must not be null. By default, property types in Kotlin cannot be null. IllegalStateException: Mockito. Kotlin When Kotlin when expression is kind of switch case in Java, but concise in syntax and extended in functionality. Val vs Var in Kotlin. Kotlin Koans. I am using kotlin view binding in my fragment. I invite you to use the nhaarman/mockito-kotlin library, it provides workarounds for this kind of call. A Kotlin-esque API for Retrofit. The compiler then knows that defensive coding is required before accessing that property. Kotlin embraces a more functional style and people should be using map/fold. Kotlin List Kotlin List is one of the three Collections (List, Set, Map). GitHub Gist: instantly share code, notes, and snippets. The "proper" use of the IllegalStateException class is somewhat subjective, since the official documentation simply states that such an exception "signals that a method has been invoked at an illegal or inappropriate time. apply plugin: 'kotlin-android' apply plugin: 'kotlin-kapt' android { dataBinding { enabled = true } } dependencies { // notice that the…. If you have a favorite idiom, contribute it by sending a comment below. The sendData() method is written in Kotlin and the second parameter cannot be null. In other words, the Java environment or Java application is not in an appropriate state for the requested operation. description // IllegalStateException: session. How to fix 'IllegalStateException' when using. myMethodName(MyClassName. Kotlin lateinit. For instance (from Mockito-kotlin 2. Today we make our way to the IllegalStateException in Java, as we continue our journey through Java Exception Handling series. IllegalStateException: any() must not be null. A Kotlin-esque API for Retrofit. When a platform value is assigned to a Kotlin variable, we can rely on type inference (the variable will have an inferred platform type then, as item has in the example above), or we can choose the type that we expect (both nullable and non-null types are allowed):. lazy is lazy initialization. In past month i did some work on Kotlin and some article you can see on this trending topic. IllegalStateException: anyObject() must not be null must not be null. IllegalStateException: dbType not support : null host name may not be null IN not IN null Name must not be nul Must be Target host Roads not only in Be Host or Object Does not Exist RAC expressions must be NOT IN java. Other threads similar to java. Kotlin Koans. I'm trying to implement my own JavaFX Node that extends Canvas. java) This example Android source code file (Observable. Kotlin lets you define out types for exactly this case, and it can infer extra information about where the types are safe to use. So I didn't have to convert all my Activities to Kotlin before I could test it. IllegalStateException: @NotNull method jetbrains/mps/dataFlow/runtime/NullableAnalysisResult. then calling code will not need to handle a null case because it is guaranteed by the compiler and Kotlin language, that returned object can not be null. The modifier can only be used on var properties declared inside the body of a class (not in the primary constructor), and only when the property does not have a custom getter or setter. I'd estimate that something like 80% of variables in an kotlin app are statically null checked. When I build my project it runs well, with no errors. IllegalStateException throwed, just change the definition of val question: String into val question: String? and try again. But what about cases when a domain-specific language is the better fit for our task? Does Kotlin have tools to change its syntax to create APIs that are more suitable for the problem? Let's take a look!. Befriending Kotlin and Mockito. Today we make our way to the IllegalStateException in Java, as we continue our journey through Java Exception Handling series. The problem though is that sometimes we do not know what we want the value to be when we initialise the value and we know that when we use it we don't want to worry about nulls. scheme=null, host=null, path=Aict/listPagedAict. fromJson(json,type) must not be null Kotlin: How to remove element from ArrayList in SharedPreferences Gson(). Passing extra's data via intent for serialization, and de-serialization on target Activity. KT-28128 MPP Kotlin/Native re-downloads POM files on IDE Gradle refresh; IDE. See the Properties and Fields documentation. These functions give Kotlin programmers a common language. Following are the steps to convert your Java File to Kotlin File : Open your Project in IntelliJ IDEA, and open the Java file. First of all, after having a created Android project in Android Studio, we need to add the Data Binding dependency and the ones of Kotlin to the build. In addition, it is not required that the cases are constant expressions as in Java. Kotlin lets you define out types for exactly this case, and it can infer extra information about where the types are safe to use. Also Kotlin has been added to Android Studio's list of supported languages recently. Kotlin is smart enough to recognize that the condition for executing the branch is that languageName does not hold a null value, so you do not have to treat languageName as nullable within that branch. 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. IllegalStateException: Target host must not be null, or set in parameters. KT-26343 "Replace 'if' expression with elvis expression" produces wrong code in extension function with not null type parameter; KT-26353 "Make variable immutable" is a bad name for a quickfix that changes 'var' to 'val' KT-26472 "Maven dependency is incompatible with Kotlin 1. {{ (>_<) }}This version of your browser is not supported. IllegalStateException: TextView must not be null (Android/Kotlin) Browse other questions tagged android android-recyclerview kotlin. So I didn't have to convert all my Activities to Kotlin before I could test it. Otherwise returns the not null value. [Solved] IllegalStateException: Could not initialize plugin MockMaker By Lokesh Gupta | Filed Under: Mockito If you are working on Spring boot 2. List is a collection of items whose position in the collection is preserved. 7 release :) I just have changed old lib to latest and it is working. In contrast, Kotlin allows us to use the when block with any built-in or user defined type. What Kotlin has that Java does not not classes. targetPackage: String: The name of the target package that the Activity is started under. This rule reports catch blocks which check for the type of an exception via is checks or casts. then calling code will not need to handle a null case because it is guaranteed by the compiler and Kotlin language, that returned object can not be null. FragmentTransaction. apply plugin: 'kotlin-android' apply plugin: 'kotlin-kapt' android { dataBinding { enabled = true } } dependencies { // notice that the…. Today we make our way to the IllegalStateException in Java, as we continue our journey through Java Exception Handling series. Android - IllegalStateException: cursor. IllegalStateException:classCaptor. The short answer is that Kotlin code is safer and more concise than Java code, and that Kotlin and Java files can coexist in Android apps, so that Kotlin is not only useful for new apps, but also. Otherwise, it returns the same argument as a non-nullable type: val strNoNull: String = checkNotNull(str - Selection from Kotlin Quick Start Guide [Book]. For example: kotlin checkNotNull(value) { "Value cannot be null!" } Why doesn't it take the message as a parameter instead? kotlin checkNotNull(value, message = "Value cannot be null!") Is it because the string isn't initialized until it's needed in the first example? Wouldn't inlining the second example produce the same effect?. question = parcel. If you do not use these functions, you will probably reinvent them. But what about cases when a domain-specific language is the better fit for our task? Does Kotlin have tools to change its syntax to create APIs that are more suitable for the problem? Let's take a look!. For java developers learning kotlin should not be tough and will be easy to grab in quick time. List is a collection of items whose position in the collection is preserved. Returns completion exception result if this deferred was cancelled and has completed, null if it had completed normally, or throws IllegalStateException if this deferred value has not completed yet. eq("toto") must not be null Is there a way to return NonNull objects from the eq method?. For instance (from Mockito-kotlin 2. KT-26343 "Replace 'if' expression with elvis expression" produces wrong code in extension function with not null type parameter; KT-26353 "Make variable immutable" is a bad name for a quickfix that changes 'var' to 'val' KT-26472 "Maven dependency is incompatible with Kotlin 1. Passing extra's data via intent for serialization, and de-serialization on target Activity. As we know all classes and methods are final be default in Kotlin, unless specifically open-ed. This annotation is present on any class file produced by the Kotlin compiler and is read by the compiler and reflection. It is a collection of random and frequently used idioms in Kotlin. Finally, Kotlin is a pragmatic language, allowing you override the type system as required. Today we make our way to the IllegalStateException in Java, as we continue our journey through Java Exception Handling series. Signals that a method has been invoked at an illegal or inappropriate time. So I didn't have to convert all my Activities to Kotlin before I could test it. List is a collection of items whose position in the collection is preserved. If you do not use these functions, you will probably reinvent them. The problem though is that sometimes we do not know what we want the value to be when we initialise the value and we know that when we use it we don't want to worry about nulls. This one scares me more. It's not an exhaustive guide, but it establishes a good foundation and provides an overview of the whole Kotlin type-safe DSL approach. KT-28128 MPP Kotlin/Native re-downloads POM files on IDE Gradle refresh; IDE. Val - Value - The object stored in val, could not vary in. However, a call to. IllegalStateException: Mockito. I invite you to use the nhaarman/mockito-kotlin library, it provides workarounds for this kind of call. It is a collection of random and frequently used idioms in Kotlin. I think we rather need a way to also trigger the "correct exception" from Mockito, because we're getting a reflection created null when Kotlin doesn't accept null (therefore IllegalStateException). SQLiteDatabase. getNodeState must not return null: @NotNull method. Android example source code file (Observable. Used to write apps that run on platforms prior to Android 3. To fill this li java. Otherwise returns the not null value. Making Kotlin classes JEE-friendly takes a bit of work. My android application using Kotlin is throwing this exception when I try to Run 'app' in the emulator o in my cellphone. What Kotlin Fixes in Java If you're not sold on Kotlin, this compilation of its most useful features, not to mention its interoperability with Java, might help change your mind. Although we are obliged to do so, it denies the security of verifying static types and as a result, Java developers must live in constant fear of the NullPointerExceptions. Kotlin embraces a more functional style and people should be using map/fold. KT-29612 jlink refuses to consume stdlib containing non-public package kotlin. Properties in Kotlin are not initialized by default. Kotlin Koans. Singletons. In our test, TestRestTemplate is defined as a nullable type, and each time we access it, we do so using the null coalescing operator "?. Kotlin can statically verify your program is null-safe during compilation — providing you stick to safe operations. Returns: true if an entity with the given id exists, false. Kotlin lateinit. AndroidFxAccount. 2, for top-level properties and local variables. gradle file of our app. You can fix that by either changing the visibility of the class that is being mocked to open or mocking the interface that this class is implementing. Press J to jump to the feed. 0 and ran a test that throws a runtime exception in my item writer. 一些在 Kotlin 中广泛使用的语法习惯,如果你有更喜欢的语法习惯或者风格,建一个 pull request 贡献给我们吧!. If you have a val variable holding a mutable object,. The modifier can only be used on var properties declared inside the body of a class (not in the primary constructor), and only when the property does not have a custom getter or setter. authenticator. Think we should get a crash-signature for Android Background Services :) Stripped from product change [@ java. So, there is much to expect from Kotlin in easing out the development efforts and good support in future. Used to write apps that run on platforms prior to Android 3. When running on Android 3. As we know all classes and methods are final be default in Kotlin, unless specifically open-ed. In this Kotlin Tutorial - Kotlin Data Class, we have learnt what a Kotlin Data Class is, how to initialize an object of data class, how to copy one data class object to other with some properties(or you can say parameters) modified, and also to access the individual parameters of Kotlin data class using component functions. I was excited to finally try the popular language Kotlin while converting a simple app from Java using the Convert Java File to Kotlin tool in Android Studio. Also Kotlin has been added to Android Studio's list of supported languages recently. Static library support version of the framework's android. Otherwise returns the not null value. If you've been following us closely, or seen us talk about Kotlin, then you already know that we've been busy at work, trying to streamline and simplify Realm Kotlin development. Seeing mutable arrays/lists, then a for loop to populate it. Finally, Kotlin is a pragmatic language, allowing you override the type system as required. Otherwise, it is enough to set to null the parent's corresponding child. IllegalStateException: implementationClass must not be null at org. In cases like that, we catch those in our viewModel and log a handled exception to crashlytics. throw new IllegalStateException ("This system does not provide an audio It's important to understand that Kotlin does not try to avoid null references as such but raises the attention for null. looking for an answer i found the procedure: Build-> Clean Project. Kotlin is smart enough to recognize that the condition for executing the branch is that languageName does not hold a null value, so you do not have to treat languageName as nullable within that branch. Use IntelliJ IDEA - Convert Java File to Kotlin File. Singletons. Throws an IllegalStateException with the result of calling lazyMessage if the value is null. Note: lateinit is supported from Kotlin 1. For information about building your media application, read the Media Apps developer guide. It contains safety features for nullability and immutability, to make your Android apps healthy and performant by default. That's why we are introducing a dedicated Kotlin support in Spring Framework 5. Null Safety Nullable types and Non-Null Types. The Kotlin Programming Language. In other words, the Java environment or Java application is not in an appropriate state for the requested operation. The problem, however, is that sometimes we do not know what. Returns: true if an entity with the given id exists, false. Every reference can potentially be null. native; Tools. It is a collection of random but frequently used idioms. Android - IllegalStateException: cursor. We're giving away four copies of Event Streams in Action and have Alexander Dean & Valentin Crettaz on-line! See this thread for details. val maybeString: String? = getString() return maybeString?. Kotlin variables that can be null must be declared using '?'. 0, we added additional nullability annotations to avoid leaking Java Platform Types and increase the overall null safety of our API. It contains safety features for nullability and immutability, to make your Android apps healthy and performant by default. Every reference can potentially be null. The problem though is that sometimes we do not know what we want the value to be when we initialise the value and we know that when we use it we don't want to worry about nulls. Current Behavior Build fails with an exception: Caused by: java. FragmentTransaction. The type of the property or variable must be non-null, and it must not be a primitive type. We can combine the Null Safety Operator with let to create null safe scoping. In the past month I did some work on Kotlin and some article you can see on this trending topic. Other threads similar to Kotlin : cardProductItem must not be null. My android application using Kotlin is throwing this exception when I try to Run 'app' in the emulator o in my cellphone. but it doesn´t worked, i know that this procedure will delete the content into the /build directory but for my experience it doesn´t work in all cases, so i tried the "raw" way, deleting the directory:. When a platform value is assigned to a Kotlin variable, we can rely on type inference (the variable will have an inferred platform type then, as item has in the example above), or we can choose the type that we expect (both nullable and non-null types are allowed):. We can combine the Null Safety Operator with let to create null safe scoping. If the method took a Position? then all would be well, but as captor. That variation takes a lazy message closure as final argument. Similarly, you can define in types for generic types that are only ever passed into methods, not returned. In past month i did some work on Kotlin and some article you can see on this trending topic. Advent of Code (log in) My programs (log in) Public links. GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Wildcard-types sure the above advantages of Kotlin must. But even though the views look like real class properties in the Kotlin code, they are synthetic, meaning accessing them means calling a hidden method in the background. IllegalStateException: @NotNull method jetbrains/mps/dataFlow/runtime/NullableAnalysisResult. Kotlin embraces a more functional style and people should be using map/fold. length } Here, we named a variable string within the block. TypeCastException: null cannot be cast to non-null type``. It contains safety features for nullability and immutability, to make your Android apps healthy and performant by default. Might not be an issue with Moshi specifically, but when deserializing objects in Kotlin, I get objects with null values even though in Kotlin I did not declare them as nulls. The type of the property or variable must be non-null, and it must not be a primitive type. Kotlin Koans. KT-28128 MPP Kotlin/Native re-downloads POM files on IDE Gradle refresh; IDE. Advent of Code (log in) My programs (log in) Public links. Kotlin lets you define out types for exactly this case, and it can infer extra information about where the types are safe to use. IllegalStateException: dtoCaptor. A lot of introductions to Kotlin start with how null is opt-in because that makes it safer — we even looked at this way back in post 8. However, this computation blocks the main thread that is running the code. Kotlin code is indeed a lot shorter and more expressive. When a platform value is assigned to a Kotlin variable, we can rely on type inference (the variable will have an inferred platform type then, as item has in the example above), or we can choose the type that we expect (both nullable and non-null types are allowed):. 7 release :) I just have changed old lib to latest and it is working. I was excited to finally try the popular language Kotlin while converting a simple app from Java using the Convert Java File to Kotlin tool in Android Studio. Returns a property delegate for a read/write property with a non-null value that is initialized not during object construction time but at a later time. - When trying to do: Mockito. The root of Kotlin's type hierarchy is the Any type (just like the Any class is the root of the class hierarchy). Signals that a method has been invoked at an illegal or inappropriate time. This is not true immutability. Note: If you are using IntelliJ IDEA or any other IDE with Kotlin Plugin, you can write Kotlin code along with Java code in the same. This comment has been minimized. Also Kotlin has been added to Android Studio's list of supported languages recently. Kotlin Data Classes. Do you have any idea how to write this as an extension function in Kotlin? I tried this: getting java. Asserting Not-Null. If I annotated my API this way, Kotlin callers would not be able to pass a null in. I was excited to finally try the popular language Kotlin while converting a simple app from Java using the Convert Java File to Kotlin tool in Android Studio. Kotlin lateinit - To declare non null Kotlin Variables without initialization, use lateinit keyword during declaration of the variable. In Kotlin non-null vals must be initialized. Be sure to check Kotlin Inheritance before you learn it. IllegalStateException: dbType not support : null host name may not be null SET NULL in-null Not Null Oracle in null not null primary key null not varchar mys null null null null NULL null NULL NULL null java. However, this computation blocks the main thread that is running the code. return null} if " NetworkResponse must be parameterized as. 一些在 Kotlin 中广泛使用的语法习惯,如果你有更喜欢的语法习惯或者风格,建一个 pull request 贡献给我们吧!. It is however considered a best practice to restrict the visibility of variables to the smallest possible scope. How can anyone be safe in Java? Many Android developers find refuge in Kotlin, a modern programming language that eliminates a lot of pain and suffering. {// non-null, but not initalized lateinit var recyclerView: RecyclerView override It will throw an IllegalStateException if the value checked. With the exponentially increasing usage of Kotlin these days, many developers face the issue of how to test the newly created Kotlin classes. Android - IllegalStateException : cursor. Properties in Kotlin are not initialized by default. Say something silly, Laugh 'til it hurts, Take a risk, Sing out loud, Rock the boat, Shake things up, Flirt with disaster, Buy something frivolous, Color outside the lines, Cause a scene, Order dessert, Make waves, Get carried away, Have a great day!. Delegated properties are attached to an instance ( of which they're the properties ), if you want the same to work, you would have to first create an activity instance, set its special properties then that instance will be discarted since you'll pass the activity's class to the Intent. The Kotlin vs Java debate is a new one, with each language having their own merits But what exactly makes them stand apart? That's what we aim to explore. Prior to 3. First of all, after having a created Android project in Android Studio, we need to add the Data Binding dependency and the ones of Kotlin to the build. The plugin will generate some extra code that will allow you to access views in the layout XML, just as if they were properties with the name of the id. length } Here, we named a variable string within the block. Asserting Not-Null. description // IllegalStateException: session. Kotlin can statically verify your program is null-safe during compilation — providing you stick to safe operations. These functions give Kotlin programmers a common language. getString(idx) must not be null; IllegalStateException target must not be null; java. Android - IllegalStateException : cursor. I can't see why this would. In contrast, Kotlin refuses to compile code that assigns or returns a null value. throw new IllegalStateException ("This system does not provide an audio It's important to understand that Kotlin does not try to avoid null references as such but raises the attention for null. The sendData() method is written in Kotlin and the second parameter cannot be null. IllegalStateException: Gson(). val maybeString: String? = getString() return maybeString?. When parsing an empty json, Moshi first initiates the class with nulls Object[] args = null; return (T) constructor. But what about cases when a domain-specific language is the better fit for our task? Does Kotlin have tools to change its syntax to create APIs that are more suitable for the problem? Let's take a look!. Context, String). IllegalStateException: implementationClass must not be null at org. readString() must not be null. Oh, one thing - I was a little weary on how big the Kotlin additional runtime components would do to the final apk size. Kotlin's type system is aimed at eliminating the danger of null references from code, also known as the The Billion Dollar Mistake. What the f**k,难道 value 的值不会默认为 null 吗?垃圾 Kotlin!!! lateinit 是一个坑,对于萌新来说还是一个不小的坑。 当我们用 lateinit 修饰类属性的时候,实际上在告诉编译器:这个属性的初始化的时机和方式由我亲自把控,你个垃圾编译器哪儿凉快哪儿待着去。. Java does not protect you from the "billion dollar mistake" - the null pointer is lurking everywhere. With the exponentially increasing usage of Kotlin these days, many developers face the issue of how to test the newly created Kotlin classes. Returns completion exception result if this deferred was cancelled and has completed, null if it had completed normally, or throws IllegalStateException if this deferred value has not completed yet. Kotlin Android Extensions is a compiler plugin that offers a convenient way of accessing views defined in XML via a property-like syntax. Prior to 3. Otherwise, it returns the same argument as a non-nullable type: val strNoNull: String = checkNotNull(str - Selection from Kotlin Quick Start Guide [Book]. Kotlin Scope Functions. This smart casting works for null checks, type checks, or any condition that satisfies a contract. any() must not be null. Both child nodes are null This case is quite simple to handle and it is the only one in which we may fail to eliminate the node: if the node is a root one, we can not eliminate it. Kotlin and Java are both JVM languages, so it should be easy to convert from one to the other, right? Not quite. Learn about infix functions, lambdas with receiver and much more.