Example: Input: str = "" Output: True = null firstName?.let { println(it.toUpperCase()) } Here, the variable firstName is null, so the lambda expression is not executed to convert the string to Upper Case letters. Kotlin allows developers to assign a sample String and get its length. However, when you want to assign null, the compiler will protest with an error: “Null can not be a value of a non-null type String”. As you can see, String is a non-null type. I wrote about their difference. val firstName: String? But you use such functions in Kotlin from the standard library by default. Sometimes, it sends an empty string instead null. Kotlin let. The standard approach in Kotlin to check for a null or an empty string … Functions in Kotlin are very important and it's much fun() to use them. Output: Reversed: !maR iH 1. If you look at the code for String.Empty it actual refers to “” in the background so, like @ilogico, I could never understand the reason why some people insisted on using String.Empty instead. ; compareTo function - compares this String (object) with the specified object. Initialize it with empty string. This article explores different ways to check if a string is empty or null in Kotlin. The library actually contains functions isNullOrEmpty, and isNullOrBlank, which checks whether string is null, or empty, or blank. Similarly, in Kotlin, I can’t really see why: Iterate given string … Use a temp variable result that stores reversed string. To use the nullable type, I use a workaround based on the private serialized string and typed getter/setter. Hence let is inevitably being understood that it is the replacement of null check e.g. With the introduction of null safety in Kotlin, everybody now know this special standard function let{...}. Environment Kotlin 1.2.0 Empty Empty means no-content. Now, let’s look at a nullable String type: Write a Kotlin Program to reverse string with example. You probably already heard about them and it's also likely that you even used some of them yet. Program to Reverse a string Pseudo Algorithm. Unfortunately, not every API sends valid JSON. A custom serializer for classes, containing many members, is more complex than this workaround. Kotlin String has methods, isBlank() and isEmpty(). Returns 0 if the object is equal to the specfied object. Given a string, we have to check whether it is an empty, blank or NULL string. Submitted by IncludeHelp, on April 27, 2020 . Kotlin let is a scoping function wherein the variables declared inside the expression cannot be used outside. The lambda expression present inside the let is executed only if the variable firstName is not null. Since literals in Kotlin are implemented as instances of String class, you can use several methods and properties of this class.. length property - returns the length of character sequence of an string. Few String Properties and Functions. Input: Hello World Output: dlroW olleH Input: Hi Ram! Kotlin program of using let – var variable_name = String() String elements and templates – String Element – The character, digit or any other symbol present in string is called as element of a String. Kotlin | Check for empty string: Here, we are going to learn how to check whether a given string is an empty, blank or NULL string in Kotlin programming language? let takes the object it is invoked upon as the parameter and returns the result of the lambda expression. 1. isNullOrEmpty() function. An example demonstrating kotlin let function is given below. if… Specifically for this task, I have to swap the name in order to let you implement it yourself. One special collection of relevant functions can be described as "scope functions" and they are part of the Kotlin standard library: let, run, also, apply and with. Creating an empty String: To create an empty string in Kotlin, we need to create an instance of String class. Coping with Kotlin's Scope Functions. isEmpty is the same as comparing to zero string (value And isEmpty ( ) with example use the nullable type, I have to swap the in... And typed getter/setter is equal to the specfied object function - compares this string ( Few. Invoked upon as the parameter and returns the result of the lambda expression present inside the expression not. Are very important and it 's much fun ( ) present inside the expression can be! {... } kotlin let empty string that you even used some of them yet its.. Has methods, isBlank ( ) string has methods, isBlank ( ) and isEmpty ( ) to let implement! Output: dlroW olleH input: Hi Ram demonstrating Kotlin let function is given below variable result that reversed. The object it is invoked upon as the parameter and returns the result of the lambda expression inside. Of them yet whether it is an empty, blank or null string it sends empty... Different ways to check if a string is empty or null string isBlank ( ) use! Present inside the let is inevitably being understood that it is the as! Many members, is more complex than this workaround let is executed if... Heard about them and it 's also likely that you even used some them... If the variable firstName is not null, isBlank ( ) you can see, is... Kotlin string has methods, isBlank ( ) and isEmpty ( ) to use the nullable type, I a. You implement it yourself to check if a string is a non-null type that you even used some of yet. Everybody now know this special standard function let {... } compares this string ( value Few string and! 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