The lambda expression present inside the let is executed only if the variable firstName is not null. Iterate given string … To use the nullable type, I use a workaround based on the private serialized string and typed getter/setter. This article explores different ways to check if a string is empty or null in Kotlin. Kotlin let is a scoping function wherein the variables declared inside the expression cannot be used outside. Coping with Kotlin's Scope Functions. 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. Program to Reverse a string Pseudo Algorithm. Kotlin allows developers to assign a sample String and get its length. Functions in Kotlin are very important and it's much fun() to use them. Initialize it with empty string. val firstName: String? With the introduction of null safety in Kotlin, everybody now know this special standard function let{...}. 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. Now, let’s look at a nullable String type: Submitted by IncludeHelp, on April 27, 2020 . The standard approach in Kotlin to check for a null or an empty string … Returns 0 if the object is equal to the specfied object. 1. isNullOrEmpty() function. Given a string, we have to check whether it is an empty, blank or NULL string. Sometimes, it sends an empty string instead null. let takes the object it is invoked upon as the parameter and returns the result of the lambda expression. I wrote about their difference. Example: Input: str = "" Output: True 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”. Use a temp variable result that stores reversed string. Few String Properties and Functions. An example demonstrating kotlin let function is given below. You probably already heard about them and it's also likely that you even used some of them yet. Kotlin program of using let – Environment Kotlin 1.2.0 Empty Empty means no-content. Similarly, in Kotlin, I can’t really see why: Write a Kotlin Program to reverse string with example. 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? The library actually contains functions isNullOrEmpty, and isNullOrBlank, which checks whether string is null, or empty, or blank. Hence let is inevitably being understood that it is the replacement of null check e.g. Output: Reversed: !maR iH 1. ; compareTo function - compares this String (object) with the specified object. Kotlin String has methods, isBlank() and isEmpty(). A custom serializer for classes, containing many members, is more complex than this workaround. Unfortunately, not every API sends valid JSON. Kotlin let. Specifically for this task, I have to swap the name in order to let you implement it yourself. = 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. isEmpty is the same as comparing to zero string (value 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. Input: Hello World Output: dlroW olleH Input: Hi Ram! As you can see, String is a non-null type. But you use such functions in Kotlin from the standard library by default. if… 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. 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