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Page 26 of 148
Difference between "fold" and "reduce" in Kotlin
Kotlin is a cross-platform and statically typed general-purpose programming language. Kotlin provides many optional methods to traverse through the collections. fold() and reduce() are two different methods, both are helpful for traversing a collection. In this article, we will see how and when to use these two methods.Example – fold()If we want to traverse through a collection serially, then we can use fold().fold() takes one initial value and one operation to perform the operation on the initial value.There are different kinds of fold(), for example, foldRight() folds from right to left. By default, fold() will traverse from left to right.The ...
Read MoreTry-with-resources in Kotlin
Kotlin is very efficient in managing the memory. Unlike Java, developers in Kotlin need not have to manage the memory explicitly. We do have different kinds of memory management techniques and Try-with-resource is one of them. In Kotlin, we have a function called 'use' which takes the burden of managing the resources automatically. This is a part of std library function provided by Kotlin.As per Kotlin documentation, use() is defined as a generic extension on all closeable types. The implementation looks like this −public inline fun T.use(block: (T) -> R): R {}In the above function, the definition block is the ...
Read MoreSwift "if let" statement equivalent in Kotlin
Swift "if let" is a conditional check operator to check whether a reference variable is NULL or not. This is a very useful technique to evaluate the unwrap optional value using swift language.In Kotlin, we can't use this operator directly. Instead, we will be using "let" and "run" to evaluate the same. In the following example, we will see how to use "let" and "run" using Kotlin library class.Example: Null Check using 'let' and 'run'In this example, we will check whether the value of a reference variable is NULL or not. If the value of the reference variable is NULL, ...
Read MoreHow to implement Builder pattern in Kotlin?
In object-oriented programming, the creation of objects is very easy via constructors when the object definitions are simple, but sometimes, it may so happen that the constructors need more variables or functions in order to initialize an object. In such cases, the "builder pattern" comes into picture which helps programmers to create small units of different objects and create a final object.A builder pattern provides an API to construct an object step- by-step.Builder patterns are particularly useful when objects need to be created dynamically.Note that it is not recommended to use builder patterns in Kotlin because we can get the ...
Read MoreHow to convert a Kotlin source file to a Java source file?
Kotlin is a statistically typed language that runs on JVM. Once a Kotlin file is compiled, it creates a .class file that can be executed on the JVM. In this article, we will see how we can convert a Kotlin source file to a Java source file. In this process, we will be taking help from different online Decompilers available on the Internet.Open VS Code.Go to the "extension" section and install "Kotlin language support for VS Code" and "Code Runner". We need these two extensions to run Kotlin in VS code environment.Install Kotlin compiler in your system as per the ...
Read MoreConvert Kotlin Array to Java varargs
Varargs, also known as "variable arguments" is a new mechanism in Java by which methods in Java can accept zero or multiple number of arguments. Before this mechanism, the only option available to achieve this type of functionality was "method overloading", but that also required multiple lines of boilerplate code.In this article, we will see how we can use Varags in Kotlin to call a function multiple times based on different types of arguments. The following example demonstrates how we can use this Varags keyword.Examplefun main() { // calling the function with 4 arguments and // passing 3 ...
Read MoreAccessing Kotlin extension functions from Java
In Kotlin, you can easily call another function by just importing the same in the current Kotlin file where your main function is running. Whatever the function we are declaring in a Kotlin file will be compiled into a static method by default, and it will be placed under the same package. The name of the newly created file will be renamed as the First letter capitalized and ".kt" extension replaced with the "Kt" suffix.In this article, we will try to get an insight into how you can use Kotlin extension methods from a Java file.ExampleLet's create a Kotlin file ...
Read MoreHow to call a function after a delay in Kotlin?
Kotlin is based on Java, hence we can use Java-based library functions to delay a function call. In this article, we will be using a Java library function to delay the function call using Timer() and schedule().Exampleimport java.util.Timer import kotlin.concurrent.schedule fun main(args: Array) { // Execution starting point println("Hello world!!") // Delay of 5 sec Timer().schedule(5000){ //calling a function newMethod() } } fun newMethod(){ println("Delayed method call!") }OutputOnce executed, the above piece of code will yield the following output −Hello world!! Delayed method call!
Read MoreWhat's the Kotlin equivalent of Java's String[]?
String is a collection which is implemented using String class. As per the Kotlin documentation, a string can be defined as follows −Class String : Comparable, CharSequenceIn Kotlin, a string is a collection of characters. Strings are immutable in nature which means they are read-only. The length and elements of a string can be modified once declared.In Java, we have an option to create an empty String array by defining it like String[]. In this article, we will see how we can achieve the same using Kotlin library function.Example: Using arrayOf()Kotlin library provides a function to create an array of ...
Read MoreHow does the reified keyword work in Kotlin?
"reified" is a special type of keyword that helps Kotlin developers to access the information related to a class at runtime. "reified" can only be used with inline functions. When "reified" keyword is used, the compiler copies the function’s bytecode to every section of the code where the function has been called. In this way, the generic type T will be assigned to the type of the value it gets as an argument.ExampleIn this example, we will see how "reified" is helpful to re-use our code and use the same function to perform similar kind of operation regardless of its ...
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