Kotlin Tutorial (original) (raw)

• Kotlin Tutorial This Kotlin tutorial is designed for beginners as well as professional, which covers basic and advanced concepts of Kotlin programming language. In this Kotlin tutorial, you'll learn various important Kotlin topics, including data types, control flow, functions, object-oriented programming, collecti 4 min read

Overview

• Introduction to Kotlin Kotlin is a statically typed, general-purpose programming language developed by JetBrains, which has built world-class IDEs like IntelliJ IDEA, PhpStorm, Appcode, etc. It was first introduced by JetBrains in 2011 as a new language for the JVM. Kotlin is an object-oriented language, and a better lang 4 min read

• Kotlin Environment setup for Command Line To set up a Kotlin environment for the command line, you need to do the following steps:Install the Java Development Kit (JDK): Kotlin runs on the Java virtual machine, so you need to have the JDK installed. You can download the latest version from the official Oracle website.Download the Kotlin com 2 min read

• Kotlin Environment setup with Intellij IDEA Kotlin is a statically typed, general-purpose programming language developed by JetBrains that has built world-class IDEs like IntelliJ IDEA, PhpStorm, Appcode, etc. It was first introduced by JetBrains in 2011. Kotlin is object-oriented language and a better language than Java, but still be fully i 2 min read

• Hello World program in Kotlin Hello, World! It is the first basic program in any programming language. Let's write the first program in the Kotlin programming language. The "Hello, World!" program in Kotlin: Open your favorite editor, Notepad or Notepad++, and create a file named firstapp.kt with the following code. // Kotlin He 2 min read

Basics

• Kotlin Data Types The most fundamental data type in Kotlin is the Primitive data type and all others are reference types like array and string. Java needs to use wrappers (java.lang.Integer) for primitive data types to behave like objects but Kotlin already has all data types as objects.There are different data types 3 min read

• Kotlin Variables In Kotlin, every variable should be declared before it's used. Without declaring a variable, an attempt to use the variable gives a syntax error. The declaration of the variable type also decides the kind of data you are allowed to store in the memory location. In case of local variables, the type o 2 min read

• Kotlin Operators Operators are the symbols that operate on values to perform specific mathematical or logical computations on given values. They are the foundation of any programming language. Example:Kotlinfun main(args: Array) { var a= 10 + 20 println(a) }Output:30Explanation: Here, ‘+‘ is an additio 4 min read

• Kotlin Standard Input/Output In this article, we will discuss how to take input and how to display the output on the screen in Kotlin. Kotlin standard I/O operations are performed to flow a sequence of bytes or byte streams from an input device, such as a Keyboard, to the main memory of the system and from main memory to an out 4 min read

• Kotlin Type Conversion Type conversion (also called as Type casting) refers to changing the entity of one data type variable into another data type. As we know Java supports implicit type conversion from smaller to larger data types. An integer value can be assigned to the long data type. Example: Javapublic class Typecas 2 min read

• Kotlin Expression, Statement and Block Every Kotlin program is made up of parts that either calculate values, called expressions, or carry out actions, known as statements. These parts can be organized into sections called blocks. Table of ContentKotlin ExpressionKotlin StatementKotlin BlockKotlin ExpressionAn expression in Kotlin is mad 4 min read

Control Flow

• Kotlin if-else expression Decision Making in programming is similar to decision-making in real life. In programming too, a certain block of code needs to be executed when some condition is fulfilled. A programming language uses control statements to control the flow of execution of a program based on certain conditions. If t 4 min read

• Kotlin while loop In programming, loop is used to execute a specific block of code repeatedly until certain condition is met. If you have to print counting from 1 to 100 then you have to write the print statement 100 times. But with help of loop you can save time and you need to write only two lines.While loopIt cons 2 min read

• Kotlin do-while loop Like Java, do-while loop is a control flow statement which executes a block of code at least once without checking the condition, and then repeatedly executes the block, or not, it totally depends upon a Boolean condition at the end of do-while block. It contrast with the while loop because while lo 2 min read

• Kotlin for loop In Kotlin, the for loop is equivalent to the foreach loop of other languages like C#. Here for loop is used to traverse through any data structure that provides an iterator. It is used very differently then the for loop of other programming languages like Java or C. The syntax of the for loop in Kot 4 min read

• Kotlin when expression In Kotlin, when replaces the switch operator of other languages like Java. A certain block of code needs to be executed when some condition is fulfilled. The argument of when expression compares with all the branches one by one until some match is found. After the first match is found, it reaches to 6 min read

• Kotlin Unlabelled break When we are working with loops and want to stop the execution of loop immediately if a certain condition is satisfied, in this case, we can use either break or return expression to exit from the loop. In this article, we will discuss learn how to use break expression to exit a loop. When break expre 4 min read

• Kotlin labelled continue In this article, we will learn how to use continue in Kotlin. While working with a loop in programming, sometimes, it is desirable to skip the current iteration of the loop. In that case, we can use the continue statement in the program. continue is used to repeat the loop for a specific condition. 4 min read

Array & String

• Kotlin Array Array is one of the most fundamental data structures in practically all programming languages. The idea behind an array is to store multiple items of the same data type, such as an integer or string, under a single variable name. Arrays are used to organize data in programming so that a related set 5 min read

• Kotlin String An array of characters is called a string. Kotlin strings are similar to Java strings but have some newly added functionalities. They are also immutable, which means we can not change the elements and length of the String. The String class in Kotlin is defined as: class String : Comparable<String 4 min read

Functions

• Kotlin functions In Kotlin, functions are used to encapsulate a piece of behavior that can be executed multiple times. Functions can accept input parameters, return values, and provide a way to encapsulate complex logic into reusable blocks of code. Table of ContentWhat are Functions?Example of a FunctionTypes of Fu 7 min read

• Kotlin Default and Named argument In most programming languages, we need to specify all the arguments that a function accepts while calling that function, but in Kotlin, we need not specify all the arguments that a function accepts while calling that function, so it is one of the most important features. We can get rid of this const 7 min read

• Kotlin Recursion In this tutorial, we will learn about Kotlin Recursive functions. Like other programming languages, we can use recursion in Kotlin. A function that calls itself is called a recursive function, and this process of repetition is called recursion. Whenever a function is called then there are two possib 3 min read

• Kotlin Tail Recursion In a traditional recursion call, we perform our recursive call first, and then we take the return value of the recursive call and calculate the result. But in tail recursion, we perform the calculation first, and then we execute the recursive call, passing the results of the current step to the next 2 min read

• Kotlin Lambdas Expressions and Anonymous Functions In this article, we are going to learn lambdas expression and anonymous function in Kotlin. While syntactically similar, Kotlin and Java lambdas have very different features. Lambdas expression and Anonymous function both are function literals means these functions are not declared but passed immedi 6 min read

• Kotlin Inline Functions In Kotlin, higher-order functions and lambda expressions are treated like objects. This means they can use up memory, which can slow down your program. To help with this, we can use the 'inline' keyword. This keyword tells the compiler not to create separate memory spaces for these functions. Instea 5 min read

• Kotlin infix function notation In this article, we will learn about infix notation used in Kotlin functions. In Kotlin, a function marked with infix keyword can also be called using infix notation means calling without using parenthesis and dot. There are two types of infix function notation in KotlinTable of ContentStandard libr 5 min read

• Kotlin Higher-Order Functions Kotlin language has superb support for functional programming. Kotlin functions can be stored in variables and data structures, passed as arguments to and returned from other higher-order functions. Higher-Order FunctionIn Kotlin, a function that can accept a function as a parameter or return a func 6 min read

Collections

• Kotlin Collections In Kotlin, collections are used to store and manipulate groups of objects or data. There are several types of collections available in Kotlin, including: Lists - Ordered collections of elements that allow duplicates.Sets - Unordered collections of unique elements.Maps - Collections of key-value pair 6 min read

• Kotlin list : Arraylist ArrayList class is used to create a dynamic array in Kotlin. Dynamic array states that we can increase or decrease the size of an array as pre requisites. It also provide read and write functionalities. ArrayList may contain duplicates and is non-synchronized in nature. We use ArrayList to access th 6 min read

• Kotlin list : listOf() In Kotlin, listOf() is a function that is used to create an immutable list of elements. The listOf() function takes a variable number of arguments and returns a new list containing those arguments. Here's an example: Kotlin val numbers = listOf(1, 2, 3, 4, 5) In this example, we create a new list ca 8 min read

• Kotlin Set : setOf() Kotlin Set interface is a generic unordered collection of elements and it does not contain duplicate elements. Kotlin supports two types of sets mutable and immutable. setOf() is immutable means it supports only read-only functionalities and mutableSetOf() is mutable means it supports read and write 5 min read

• Kotlin hashSetOf() Kotlin HashSet is a generic unordered collection of elements and it does not contain duplicate elements. It implements the set interface. hashSetOf() is a function that returns a mutable hashSet, which can be both read and written. The HashSet class store all the elements using the hashing mechanism 5 min read

• Kotlin Map : mapOf() Kotlin map is a collection that contains pairs of objects. Map holds the data in the form of pairs which consists of a key and a value. Map keys are unique and the map holds only one value for each key. Kotlin distinguishes between immutable and mutable maps. Immutable maps created with mapOf() mea 6 min read

• Kotlin Hashmap Kotlin HashMap is a collection which contains pairs of object. Kotlin Hash Table based implementation of the MutableMap interface. It stores the data in the form of key and value pair. Map keys are unique and the map holds only one value for each key. It is represented as HashMap<key, value> o 7 min read

OOPs Concept

• Kotlin Class and Objects In Kotlin, classes and objects are used to represent objects in the real world. A class is a blueprint for creating objects (a particular data structure), providing initial values for state (member variables or fields), and implementations of behavior (member functions or methods). An object is an i 4 min read

• Kotlin Nested class and Inner class Nested Class In Kotlin, you can define a class inside another class, which is known as a nested class. Nested classes have access to the members (fields and methods) of the outer class. Here is an example of a nested class in Kotlin: Kotlin class Car { var make: String var model: String var year: In 5 min read

• Kotlin Setters and Getters Properties are an important part of any programming language. In Kotlin, we can define properties in the same way as we declare another variable. Kotlin properties can be declared either as mutable using the var keyword or as immutable using the val keyword. Syntax of Property var <propertyName 5 min read

• Kotlin | Class Properties and Custom Accessors The basic and most important idea of a class is Encapsulation. It is a property to encapsulate code and data, into a single entity. In Java, the data are stored in the fields and these are mostly private. So, accessor methods - a getter and a setter are provided to let the clients of the given class 2 min read

• Kotlin Constructor A constructor is a special member function that is invoked when an object of the class is created primarily to initialize variables or properties. A class needs to have a constructor and if we do not declare a constructor, then the compiler generates a default constructor. Kotlin has two types of co 7 min read

• Kotlin Visibility Modifiers In Kotlin, visibility modifiers are used to control the visibility of a class, its members (properties, functions, and nested classes), and its constructors. The following are the visibility modifiers available in Kotlin: private: The private modifier restricts the visibility of a member to the cont 6 min read

• Kotlin Inheritance Kotlin supports inheritance, which allows you to define a new class based on an existing class. The existing class is known as the superclass or base class, and the new class is known as the subclass or derived class. The subclass inherits all the properties and functions of the superclass, and can 10 min read

• Kotlin Interfaces In Kotlin, an interface is a collection of abstract methods and properties that define a common contract for classes that implement the interface. An interface is similar to an abstract class, but it can be implemented by multiple classes, and it cannot have state. Interfaces are custom types provid 7 min read

• Kotlin Data Classes We often create classes to hold some data in it. In such classes, some standard functions are often derivable from the data. In Kotlin, this type of class is known as data class and is marked as data. Example of a data : data class Student(val name: String, val roll_no: Int) The compiler automatical 4 min read

• Kotlin Sealed Classes Kotlin introduces a powerful concept that doesn't exist in Java: sealed classes. In Kotlin, sealed classes are used when you know in advance that a value can only have one of a limited set of types. They let you create a restricted class hierarchy, meaning all the possible subclasses are known at co 4 min read

• Kotlin Abstract class In Kotlin, an abstract class is a class that cannot be instantiated and is meant to be subclassed. An abstract class may contain both abstract methods (methods without a body) and concrete methods (methods with a body). An abstract class is used to provide a common interface and implementation for i 5 min read

• Enum Classes in Kotlin In programming, sometimes there arises a need for a type to have only certain values. To accomplish this, the concept of enumeration was introduced. Enumeration is a named list of constants. In Kotlin, like many other programming languages, an enum has its own specialized type, indicating that somet 5 min read

• Kotlin extension function Kotlin gives the programmer the ability to add more functionality to the existing classes, without inheriting them. This is achieved through a feature known as extensions. When a function is added to an existing class it is known as Extension Function. To add an extension function to a class, define 5 min read

• Kotlin generics Generics are the powerful features that allow us to define classes, methods and properties which are accessible using different data types while keeping a check on the compile-time type safety. Creating parameterized classes - A generic type is a class or method that is parameterized over types. We 6 min read

Exception Handling

• Kotlin Exception Handling | try, catch, throw and finally An exception is an unwanted or unexpected event, which occurs during the execution of a program i.e at run time, that disrupts the normal flow of the program’s instructions. Exception handling is a technique, using which we can handle errors and prevent run time crashes that can stop our program. Th 6 min read

• Kotlin Nested try block and multiple catch block Nested try block - In this article, we are going to learn nested try-catch block and multiple catch block. Nested try block is a block in which we can implement one try catch block into another try catch block. The requirement of nested try-catch block arises when an exception occurs in the inner tr 3 min read

Null Safety

• Kotlin Null Safety Kotlin has a powerful type system that helps developers avoid one of the most common problems in programming: Null Pointer Exceptions. In many languages like Java, trying to use a variable that holds null can cause a NullPointerException (NPE), which can crash your application if not handled properl 7 min read

• Kotlin Type Checking and Smart Casting Kotlin allows you to determine the type of a variable at runtime using the is operator. This feature is commonly used to handle logic based on the dynamic type of an object, enabling type-safe operations within control flow blocks.Using if-else Blocks for Type CheckingKotlinfun main() { val name = " 3 min read

• Kotlin Explicit Type Casting Kotlin provides both smart casting and explicit type casting mechanisms to handle type conversions safely and effectively. In Smart Casting, we generally use is or !is an operator to check the type of variable, and the compiler automatically casts the variable to the target type, but in explicit typ 3 min read