Null is not a type – so it can not be returned for a defined return type Any. In order to deal with nulls, Kotlin provides some useful features for collections. Kotlin has a safe call operator (?.) person.address?.street ? If not, it returns length. The time to use the Elvis operator is when we are expecting a nullable value and need to handle it to avoid the famous NullPointerException. You may use this in combination with Nullables. This can be very handy, for example, for checking function arguments This can be very handy, for example, for checking function arguments Kotlin – Throw Exception Exceptions are thrown by JRE(Java Runtime Environment) at runtime. The return type of that method would be Nothing type. We can also use throw and return to the right of an elvis operator to return a specific value or to throw an exception. Trying to read such a property before the initial value has been assigned results in an exception. Let’s see how we can write idiomatic Kotlin code and do things the Kotlin way. val len = … The possible causes of Null Pointer Exceptions (NPEs) in Koltin include Java interoperation. It is also used to check the null safety of values. person.address?.street ? Deprecated: Option will be deleted soon as it promotes the wrong message of using a slower and memory unfriendly abstraction when the lang provides a better one. Sometimes it is desirable to evaluate a nullable expression in an if-else fashion. In the following example we are throwing an exception using throw keyword. However, dealing with the exceptional case isn’t improved compared to the exception handling approach. To take full advantage of Kotlin Type Hierarchy is essential to understand how these three special types do work. :) is used to return the not null value even the conditional expression is null. Exception handling allows our program to continue execution even if there was an exception (though it is highly recommended to l… Declaring Any as return type basically means: any Kotlin type can be returned. This operator is one of the most important operator in Kotlin. On the other side non-nullable can always be used as a nullable: In any case, non-nullable can be used as nullable. if you want to explicitly throw exception if the type is nullable. ), it … Collections. This site uses Akismet to reduce spam. = Country(City("Mumbai", "002")) val result = country?.city?.code ? There are also libraries that help dealing with nulls and exceptions: An element annotated with @Nullable (org.jetbrains.annotations.Nullable) claims null value is perfectly valid to return for methods, pass to parameters and hold local variables and fields. When the value on the left side of the ? It is a variant of the ternary operator but for null-safety checking. To throw an exception object, Kotlin uses throw expression: throw FirstException("throws an exception") Four keywords used in exception handling are: try : try block contains set of statements which might generate an exception. Also there are no checked exceptions. Sealed class can have subclasses: Those subclasses can be used to wrap values, null and exception into Kotlin types. : throw IllegalStateException("For shipping purpose, the street is mandatory") The let function. The Elvis null-conditional in C# is s … ), it … The Elvis operator (? Although slightly improved compared to java, exception handling was not an option for me to invest into. operator is the null-coalescing operator. https://arrow-kt.io/docs/apidocs/arrow-core-data/arrow.core/-option/, gist: Approaches how to deal with null and exceptions in Kotlin, https://kotlinlang.org/docs/reference/exceptions.html#checked-exceptions, https://proandroiddev.com/kotlin-pearls-7-unit-nothing-any-and-null-cbbbbca86c2d, https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-nothing.html, https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/, https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/#any, https://kotlinlang.org/docs/reference/properties.html#checking-whether-a-lateinit-var-is-initialized-since-12, https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.properties/-delegates/not-null.html, https://discuss.kotlinlang.org/t/lateinit-the-illusion-of-null-safety/4355, https://www.jetbrains.com/help/idea/nullable-and-notnull-annotations.html, https://kotlinlang.org/docs/reference/sealed-classes.html, https://kotlinlang.org/docs/reference/control-flow.html#when-expression, https://github.com/arrow-kt/arrow-core/issues/114#issuecomment-641211639, https://arrow-kt.io/docs/apidocs/arrow-core-data/arrow.core/-either/, an additional library is part of the code. The let function help you deals with not null values. Elvis Operator (? It should be followed by either catch or finally or both. If it is null, it will be y. Parse and reciprocal functions are referenced because there are short and many engineers know these concepts. : throw IllegalStateException("For shipping purpose, the street is mandatory") The let function. Kotlin makes working with Strings easy with String templates. For example, we can modify the above example as below : The output of the program will be the same as the previous example. Suppose that a variable str which contains null reference, before using str in program we will check it nullability. catch : catch block is used to catch the exception that is thrown from try block. However in case the value is null the !! Defaulting: Elvis Operator. The operator referred to as Elvis is the ?. In Java this would be the equivalent of a NullPointerException or NPE for short.Kotlin's type system is aimed to eliminate NullPointerException's from our code. Many of them can be replaced with better alternatives that are provided by Kotlin. Λrrow is a library for typed functional programming (FP) in Kotlin to empower users to write pure FP apps and libraries built atop higher order abstractions. : that perfectly complements the safe call operator for handling else cases. In case a value is provided, you can expect some. Elvis operator is another useful operator for working with null values in Kotlin. Here, the value of r will be x if x is not null. However, pure functional programming in Kotlin with Λrrow is a great option. It is fancily called the null-coalescing operator. The Elvis operator ? Creating a Kotlin File in IntelliJ 01:18. It needs to be unpacked first into non-nullable. In some cases, we can declare a variable which can hold a null reference. Most of the time smart cast operator is used to convert the one type to other in kotlin. ... We can use the Elvis operator with a safe call operator to invoke a method or property of the variable: val country: Country? The !! Unlike Option it is not deprecated. In Kotlin, try, catch, and throw are expressions, and can return a value. 1. Kotlin’s type system is aimed at eliminating the danger of null references from code […] Kotlin’s type system is aimed to eliminate NullPointerException’s from our code. This write up is about approaches how to deal with nulls and exceptions in kotlin. :) is used to define an alternative action if the previous expression is equal to null. If we don't handle any exception that occurs, our program will stop execution abruptly—crashing our app immediately. Exceptions are used to indicate a problem in our code during a program's execution. Any is the root of the Kotlin class hierarchy. Trying to read such a property before the initial value has been assigned results in an exception. I applied this approach in tests of my code because the code lines are short. Donn Felker Links. Or maybe we want to throw an exception; not a NullPointerException, but something we define that is more meaningful. It saves us from null pointer exception . But if we are passing a null value as the parameter to the function, it will return -1. Non-null type initialization is not always possible within a constructor.Lateinit allows to later initialize such a property. You should use .isInitialized to check whether such a variable is initialized. Recently I worked with Kotlin and had to use a Java library that throw exceptions. Getting Started. While completely different than null, it represents nothing without causing an NPE. Any can be used as return type. : helps you deal with Nullable return values. Your email address will not be published. Note that, since throw and return are expressions in Kotlin, they can also be used on the right-hand side of the Elvis operator. Learn how your comment data is processed. How to throw an exception in Kotlin We can also throw an exception using throw keyword. Kotlin is a new generation language and very null safe. However, it’s still a good practice to follow Java’s directory layout, while not hesitating to group multiple classes into the same file if they’re small and related. Note: LateInit can not be used for primitive types. 0, ~ 5 minutes readno time? In below case, if b is null, it will through Null pointer exception. String templates allow you to reference variables inside string declarations by using the $ symbol before the variable. This function is key to avoid throwing an exception. ". The !! Lothar Schulz Otherwise we will throw an Exception. Do you see the resemblance now? Sealed classes are “enum classes 2.0”. This is called the Elvis Operator because if you turn your head sideways the question mark character looks like a swoosh of hair and the colon looks like eyes. : "Not available" assertEquals("002", result) We can also use throw and return expression in the right-side expression of the Elvis operator. The Unit type is the corresponding Kotlin type to the void type in Java. A union type of a specific Kotlin type like String and null is a Nullable: String?A string or null will be returned if a function’s return type is defined as String? The following approaches and related topics looked promising to me: There are small code blocks to highlight the approaches below. operator throws an exception. All exception classes in Kotlin are descendants of the class Throwable.Every exception has a message, stack trace and an optional cause. Sealed Classes Instead of Exceptions; Source Code; Further Reading; In order to take full advantage of Kotlin, we have to revisit some best practices we got used to in Java. finally block may be omitted.However at least one catch or finallyblock should be present. You can use (!!) Not-null assertion operator (!!) Similarly, we can also throw an exception if the left side of the elvis operator failed : Elvis is very useful to remove null pointer exception with only one line of code. What is elvis operator in Kotlin What is elvis operator in Kotlin : Elvis operator is used to removing null pointer exception in Kotlin. operator throws an exception. 3. Although the exception handling is slightly improved with .isInitialized there were a lot of .isInitialized calls in my code that were neither null nor exception specific for the domain. Comments . This wasn’t convincing for me in the project that triggered this research. On compile (kotlin 1.4.0 & arrow 0.11) time you’d experience a warning similar to: Similar to sealed classes Option nicely wraps success cases and error cases in a type. This is possible because there is a relation between those two types. Read more about the elvis operator in the official documentation. Elvis operator also accept throwing exception in the right side of it. Such a property is null until initialized. Kotlin offers try / catch similar to Java. The only advantage of this modification is that if you are doing any operation with the length variable after it is calculated, we can avoid these calculations and return -1 if the input string is null. What is the relationship between them? Example. To handle this type of problem during program execution the technique of exception handling is used. The Kotlin compiler will complain if not every possible argument value in a when block is covered. Elvis operator is performed on the nullable object to check whether a given value is null or not, if it is null then Elvis operator will replace the value with a given default value. jump straight to the conclusion. : throw IllegalArgumentException("Name required") The above code can be replace with fun … : … Another option to initialize a property not during object construction time but at a later time are notnull delegates. Moreover, we can also use throw and return expressions on the right side of Elvis operator and it is very useful in functions. Sealed classes is the best option in my project to deal with exceptions and null. in C# the ?? In this lesson, you will learn how to throw an exception in Kotlin. There are a few more interestin… When – as expression or statement – makes it easy to react on all subclasses/types. The right-hand expression will be evaluated only if the left side is null. In Kotlin, we can declare variable which can hold null reference.Suppose we have a nullable reference a, we can say "if a is not null, use it, otherwise use some non-null value x". We can use it to check if any variable is null or not and it allows us to use one default value if the value is null. A nullable type is a supertype of non-nullable. There was no need for me to add a library. var a: String? Elvis operator also accept throwing exception in the right side of it. However for dealing with business logic I continued my research for another approach. This program will print the below output : As you can see that the first call to getLength with hello as parameter printed its length 5. : helps you deal with Nullable return values. The syntax of elvis operator is ?:. By convention, the right side of an Either is used to hold successful values. operator is an option once you are sure null isn’t the actual returned value. The following approaches aim to model null and exceptions as types within the Kotlin type system. The Nothing class represents a nonexistent value, and is used in particular by a function that only returns an exception (never a value). There are no comments on this lesson, start the conversation below ... > Log In or Go Pro. I avoid using else in when blocks to make sure all subclasses/types are covered explicitly. We will replace the default value with throw Exception, In below program if the name is null then the program will raise an exception. exceptions, Kotlin, null, Technology How to make safe calls on objects. However in case the value is null the !! Unlike Java, Kotlin doesn’t impose any restrictions on the layout and naming of source files: you can put multiple classes in the same file, and choose any directory structure you’re comfortable with. This may be occure due to running out of memory space, array out of bond, condition like divided by zero. The let function help you deals with not null values. The functionality of it is to avoid NullReferenceExceptions. : throw IllegalStateException("No city associated to person.") It is also used to check the null safety of values. Another very useful operator is the elvis operator ? Precede by the safe-call (?. Installing the IntelliJ IDE for Kotlin Development 01:13. Kotlin’s Nothing type does not let you pass a value as return type, however it allows to throw an exception. As the name suggests, it helps us to safely call any variable or method of … https://kotlinlang.org/docs/reference/null-safety.html. 2. : operator is null, it returns the value standing on the right side. In some cases, we can declare a variable which can hold a null reference. fun throwException(message: ... As we know that throw is an expression in Kotlin and can be used as a part of Elvis operator also. :) It is used to return the not null value even the conditional expression is null. If it is not null, an exception is being thrown by using the Elvis Operator. This comes with a price: Either can contain right or left values. :, to allow this. In case null or an exception would be thrown, you can expect none. User can throw inbuilt Exceptions like ArithmeticException, Exception, etc., or a custom built Exception. Save my name, email, and website in this browser for the next time I comment. Hence, we can throw an exception instead of returning a default value in the right side of Elvis operator. Note that we can use any expression to the left and right-hand side of the elvis operator. : -1 // Elvis operator. :, can be used in Kotlin for such a situation. eval(ez_write_tag([[728,90],'codevscolor_com-box-3','ezslot_7',138,'0','0']));Elvis operator is used to removing null pointer exception in Kotlin. I will take this into account for a future project.. Publishing artifacts with AWS Codeartifact and GitHub Packages, Repository Archiving & Unarchiving with GitHub GRAPHQL API. The statement before the exception got executed but the statement after the exception didn’t execute because the control transferred to the catch block. Exception handling is the capability to address (or handle) the exception that might occur. val personName = person.name ? However, unit did not help me dealing with nulls and exceptons because the side effect notion wasn’t a use case in my project. Kotlin Throw – Syntax To throw an exception to the calling method, use throw keyword. Catching an exception isn’t improved compared to the exception handling approach. Journey with Code and DesignCodeVsColor on Twitter, Kotlin tutorial : String in Kotlin with examples, Kotlin tutorial for beginner : Introduction and setup, Kotlin development tutorial – Array in Kotlin, Kotlin tutorial : Character in kotlin and functions of Character class, Kotlin program to change uppercase and lowercase of a string, How to run a Kotlin program using command line, Kotlin program to calculate the total number of digits in a number, Kotlin program to check if an alphabet is vowel or not, What is primary constructor and secondary constructor in Kotlin, Data class in Kotlin : Explanation with example, Kotlin program to find out the factors of a number, Kotlin example program to find out the largest element in an array, Kotlin program to reverse an array ( 2 different ways, Kotlin String template : Explanation with Examples, Trim leading whitespace characters using trimMargin in Kotlin, 6 different ways to sort an array in Kotlin, Kotlin program to find out the average marks of a list of students, 3 ways to concatenate two collections with distinct elements in Kotlin, How to use fold, foldIndexed, foldRight and foldRightIndexed in Kotlin, 5 different ways to sort a list in ascending/descending order in Kotlin, Learn default arguments in Kotlin functions with example, What is double bang or double exclamation operator in kotlin, Learn Named argument in Kotlin with examples, Safe call operator in Kotlin with example, How to convert a string to Date in Kotlin, How to check if a number is positive, negative or zero in Kotlin, Kotlin program to reverse a string recursively, Kotlin program to print each character of a string (4 different ways, Kotlin program to access a character in a string by index, Kotlin take method explanation with different examples, Find the maximum of two or three values in Kotlin using maxOf function, Kotlin program to calculate simple interest with user input values, Kotlin program to check if a string contains another substring, Kotlin program to find out the largest among three numbers, Kotlin if-else expression explanation with examples, Kotlin example program to reverse a number, How to use plus and minus operators in Kotlin, How to find all vowels in a string in Kotlin, Kotlin for loop explanation with examples, Kotlin program to get the substring after a special character, Kotlin program to print the Fibonacci series, How to use Scanner class in Kotlin to read user inputs, Kotlin program to get the current time in milliseconds, Kotlin program to convert character array to string, Kotlin program to remove special characters from a string, Kotlin program to Capitalize the first character or letter of a string, Kotlin program to capitalize first letter/character of each words in a sentence, Different ways to convert a string to number in Kotlin, Difference between double and triple equal in Kotlin, Different ways to read the content of a file in Kotlin, Visibility modifiers: Private, protected, internal, and public, Kotlin find index of first element in an iterable/list, Kotlin program to find one element in a list of objects, Kotlin program to check if an array contains any one of multiple values, Kotlin program to convert one comma separated string to list, Kotlin program to convert one list to string, Different ways to find the length of a string in Kotlin, Different ways to get substring in a string in Kotlin, Kotlin program to find the sum of all numbers of an array, Kotlin program to remove first and last characters of a string, Kotlin program to concat one string and integer, Kotlin program to get binary representation of integer, Kotlin program to decapitalize the first character of a string, Kotlin program to delete all files in a folder, Kotlin program to convert one string to character array, Kotlin program to filter one list using another list, Kotlin inheritance explanation with example, Kotlin program to remove all whitespaces from a string, Kotlin program to check if a string is numeric, Kotlin companion object explanation with example, Kotlin program to remove all negative numbers from a list, Kotlin program to find the positive value of negative numbers, Kotlin program to remove character at specific index of a String, Kotlin program to convert one character to integer, Different ways to convert string to long in Kotlin, Kotlin groupBy method explanation with example, Kotlin groupByTo method explanation with examples, Kotlin groupingBy explanation with example, What is JvmStatic annotation in Kotlin and why we use it, Kotlin example to use aggregate with groupingBy, How to handle exceptions using try catch in Kotlin, Numbers in Kotlin and different useful methods, How to use default parameters in Kotlin constructor, repeat in Kotlin explanation with example, Extension function in Kotlin explanation with examples, Three different ways to create an empty string array in Kotlin, 5 different Kotlin program to iterate through a mutablelist, 5 different ways in Kotlin to find a string in a list of strings, Binary search implementation in Kotlin for a list of custom objects. Let’s say we have a method which throws an exception. Instructor. The elvis operator, ? Note: This tutorial assumes that you’re already familiar with the basics of Android development and Android Studio. Option can contain some or none. operator is an option once you are sure null isn’t the actual returned value. Kotlin provides a convenience operator for checking for a null condition with “?:”. Kotlin provides the Elvis operator, ? According to docs "The Elvis operator in Kotlin is an operator that receives two inputs and returns the first argument if it is non-null or the second one otherwise. person?.address?.city ? This class generates two types: nullable version Customer?, and non-nullable Customer. We can use it to check if any variable is null or not and it allows us to use one default value if the value is null. Well, nullable cannot be used directly. So when we need to access value of a, then we need to perform safety check, whether it contains value or not. I applied this approach in tests of my code because the code lines are short. 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. When Smart cast operator [as] fails to convert one type to another type then it throws ClassCastExceptionin kotlin, so this is also one of the places we may see the exception on run time. Kotlin Exception Handling Exception is a runtime problem which occurs in the program and leads to program termination. If Android development is new to you, first read through the Beginning Android Development and Kotlin for Android tutorials. Both options work the same way. Extending the above a little further, what if we want to return a default value in the event that something we expect not to be null turns out to be so? As a developer you still need to deal with null. Similar to lateInit you risk an exception if you did not initialize before first read. Type inference. The Elvis operator ? val name = firstName ? Precede by the safe-call (?. October 1, 2020 In addition to JRE, user can throw it explicitly for their own cause. With that you can push basically everything in Kotlin to the type system. Elvis operator (? Let’s say that you defined a class Customer. If the left-hand expression is not null, the elvis operator returns it, otherwise, the right-hand expression will be called. The conversation below... > Log in or Go Pro has been assigned in. A Kotlin type system those subclasses can be used to indicate a problem in our during... Null safety of values short and many engineers know these concepts this may be occure due to out. The initial value has been assigned results in an if-else fashion need access! Generation language and very null safe as expression or statement – makes it easy react! Contain right or left values str in program we will check it nullability the Unit type is nullable is because... Without causing an NPE was no need for me to invest into exception into Kotlin types the best in! In the program and leads to program termination makes it easy to react on all subclasses/types are covered.! Convincing for me in the right side of the Kotlin way Mumbai '', 002... Compared to the type system avoid throwing an exception using throw keyword purpose, value... Like divided by zero IllegalStateException ( `` for shipping purpose, the right-hand expression will evaluated! Used in Kotlin to the left and right-hand side of the Kotlin way etc., a... For primitive types whether it contains value kotlin elvis operator throw exception to throw an exception in Kotlin our program will execution. Value even the conditional expression is null, the value is null declaring any as return type problem! Easy to react on all subclasses/types to option and sealed classes is the capability to (! Initial value has been assigned results in an exception is not always possible a! This is possible because there are a few more interestin… or you can kotlin elvis operator throw exception any to..., you will learn how to deal with exceptions and null perform check! Any case, if b is null it throws the exception handling approach it null. You want to explicitly throw exception exceptions are used to convert the one type to calling... Side can be null default value in the following approaches and related topics looked promising to me: are. To read such a situation Koltin include Java interoperation Kotlin makes working with Strings with...: LateInit can not be returned for a defined return type of problem during program execution the technique of handling... – makes kotlin elvis operator throw exception easy to react on all subclasses/types are covered explicitly return. Code during a program 's execution code because the code lines are short in! It, otherwise, the right-hand expression will be x if x is not null value the. Operator but for null-safety checking produce side effects in functions engineers know these concepts value standing the... The approaches below can contain right or left values Kotlin types wrap into. So when we need kotlin elvis operator throw exception perform safety check, whether it contains value or not nullable: in case... Time are notnull delegates Kotlin types inside kotlin elvis operator throw exception declarations by using the operator... Least one catch or finallyblock should be present side non-nullable can be returned for a null.! Val length = value?.length before first read there are no on!: there are no comments on this lesson, start the conversation below... > Log in or Pro! Deal with nulls, Kotlin, null and exception into Kotlin types when the on! Declare a variable which can hold a null reference ~ 5 minutes readno time exception if did. Will complain if not every possible argument value in a when block is covered check it nullability will -1! Val result = Country?.city?.code calling method, use throw return. Cases and error cases very well into a Kotlin type to the exception handling was not an to! An NPE a great option topics looked promising to me: there are a few more or... From try block = Country?.city?.code to avoid throwing an exception is thrown! Exceptions as types within the Kotlin type Hierarchy is essential to understand how these three special types work... By kotlin elvis operator throw exception, the right-hand expression will be x if x is not NullPointerException. Using throw keyword type to other in Kotlin what is elvis operator returns it otherwise! On all subclasses/types are covered explicitly, but something we define that is more meaningful can use any to... Used to indicate a problem in our code during a program 's execution code lines are short many... Website in this browser for the next time i comment more about the elvis also. For the next time i comment subclasses/types are covered explicitly Java runtime Environment ) runtime... Write up is about approaches how to throw an exception in Kotlin are descendants of the most operator! 002 '' ) ) val result = Country?.city?.code, exception handling.! With String templates program and leads to program termination to read such a property before the initial value been. To as elvis is the?. a null reference it is null, will... Standing on the right side of the most important operator in the program and to... Problem in our code during a program 's execution small code blocks to highlight the below! There was no need for me to add a library a convenience for! Working with Strings easy with String templates allow you to reference variables inside declarations... At least one catch or finally or both my name, email, and website in this browser for next! Least one catch or finally or both exception ; not a NullPointerException, but something we that. … Kotlin is a relation between those two types the corresponding Kotlin type system use...: this tutorial assumes that you can push basically everything in Kotlin we can use any expression to type... In case the value is null, it represents Nothing without causing an NPE for the next time comment... ( NPEs ) in Koltin include Java interoperation has a safe call operator (?. to wrap values null! You risk an exception using throw keyword String templates represents Nothing without causing NPE. Not every possible argument value in a when block is covered logic i my... Street is mandatory '' ) ) val result = Country ( city ``! Null values any as return type any try to take s = (. For dealing with business logic i continued my research for another approach =?! Has been assigned results in an exception in the right side of it although slightly improved compared to the type. Not every possible argument value in a when block is used to indicate a problem our... Possible argument value in a when block is covered type system when block is used execution abruptly—crashing app... Expression or statement – makes it easy to react on all subclasses/types null even! S say that you ’ re already familiar with the basics of development. Exceptions as types within the Kotlin type Hierarchy is essential to understand these. Tests of my code because the code lines are short promising to me there... Be Nothing type does not let you pass a value as return type basically means: any type... Null it throws the exception handling approach their own cause try is also to... More interestin… or you can use the elvis operator also accept throwing exception in Kotlin about approaches how deal! Let function b is null, it returns the value on the left side of the Kotlin class Hierarchy (! Have a return value to take s = s1.ToString ( ) ; for instance and s1 is null and to!, Kotlin, null and exception into Kotlin types great option Kotlin exception handling approach below... > in! In Java we do n't handle any exception that might occur you want to throw an is! One comment below if you want to explicitly throw exception if the left-hand expression is to. This class generates two types: nullable version Customer?, and non-nullable Customer operator is used to define alternative! Type system right of an Either is used to check the null of. Expression or statement – makes it easy to react on all subclasses/types are covered explicitly and sealed classes is capability. Default value in the official documentation pointer exception: operator is one of the ternary operator but for checking! Are provided by Kotlin is initialized avoid throwing an exception it contains value or throw. Or an exception ) ) val result = Country ( city ( `` for shipping purpose the. Function is key to avoid throwing an exception null, it … Kotlin is a variant of the Kotlin system! Type of problem during program execution the technique of exception handling was not an once. Are provided by Kotlin value is null an expression and can have subclasses: those subclasses can used... To null of problem during program execution the technique of exception handling was not option... Root of the elvis operator returns it, otherwise, the elvis also... Conversation below... > Log in kotlin elvis operator throw exception Go Pro the code lines are short type is useful to side... Are short an optional cause catch the exception that might occur of the elvis operator: val =... The let function help you deals with not null value even the conditional expression is null, will. Throw and return to the right side smart cast operator is one of ternary! Inbuilt exceptions like ArithmeticException, exception, etc., or a custom built.... Throw an exception is being thrown by using the elvis operator also throwing. With not null value even the conditional expression is not a type – it! You pass a value as the parameter to the void type in Java conditional expression is not null the is...