Kotlin Tutorial


It’s an open source project and it can be used to develop any type of application including Android apps, iOS apps or web applications. In this tutorial we will learn how to write some basic code in Kotlin language which will help us write faster and error-free code.


Kotlin is an advanced programming language for the Android platform. It was developed by JetBrains, the same company that created IntelliJ IDEA, which is a popular IDE for Java. Kotlin is a statically typed language and has support for coroutines (a way of executing multiple statements in parallel), algebraic data types (like lists or maps) and more.

Kotlin can also be used as part of your existing Java codebase—you don't have to convert it all at once! This makes it easy to get started with Kotlin without having to worry about learning too much new syntax or techniques right away.

Environment setup

The first step is to install a JDK and Android Studio. If you don't have a JDK, we recommend you download the latest version from Oracle's website.

Then, download and install the Android SDK from here: https://developer.android.com/sdk/index#downloads

Finally, install Kotlin plugin for Android Studio using this guide: http://docs.jetbrains.com/toolbox2/#installation

Basic Syntax

Kotlin is a statically-typed language, which means that the developer specifies types for each variable. The compiler checks for errors and will warn you about any potential problems.

Kotlin is also a modern, pragmatic and highly expressive programming language for JVM and Android with 100% compatibility with Java. It's easy to learn, has a concise syntax similar to Scala (but not quite as terse) while still supporting all of the same classes/interfaces/constructors/methods etc., so if you know Java or another object-oriented language then learning Kotlin shouldn't be too hard!


OOPs are a set of programming techniques used to create software. In Kotlin, these techniques are mostly used in the traditional way they have been implemented since the beginning of time: classes, inheritance and polymorphism.

Inheritance is when one class inherits properties and methods from another class (or multiple other classes). Polymorphism allows you to treat different types as if they were all the same type; this means you can use them interchangeably without having to explicitly cast them when needed. Encapsulation protects internal data from being accessed or changed by external users who don't need access; this helps prevent mistakes that might occur due to errors or misunderstandings about how things work internally within your application codebase.*


Constructors are used to initialize an object and can be overloaded. You can declare a constructor in the class or you can use a separate file for it. A constructor that does not take any arguments is called a default constructor, while one that takes no arguments and returns null is called an empty constructor.

A good practice is to define constructors as private members of your classes so that you don't have to worry about accidentally invoking them from outside of their scope when initializing objects with constructors defined elsewhere (for example: val myClass = AnotherClass()).


Inheritance is a way of reusing code. It allows us to reuse the code of a class and add more functionality to it. In this tutorial, we will learn how inheritance works in Kotlin.

Inheritance is one of the most powerful features offered by object-oriented languages like Java or C++ (and therefore also Kotlin). It enables you to implement polymorphism by inheriting from multiple classes which define similar behavior but have minor differences so that they can fit together well together in an application context. For example if we wanted our Person class as well as its superclass Employee then we could inherit from both of them instead of creating two separate classes just for them!

Inheritances are usually implemented using virtual functions; when they are overridden by subclasses they will no longer work correctly unless all their overrides have been declared before being defined within the child class definition itself - otherwise there will be errors whenever those overriding methods are called during runtime execution time due either because they were not declared beforehand or because some other condition has changed since then causing unforeseen side effects after compilation has finished successfully without any problems occurring beforehand due


Interfaces are a type of class that can be used to define the behavior of your objects. An interface is a collection of related methods and properties, but it doesn't have any implementation details.

An interface defines a set of methods and properties that must be implemented by any class that implements the interface: they're required by all classes that conform to it, but they don't provide any information about how those methods or properties should actually work. For example:


Packages are used to organize code into a project, file and module.

Packages can also be used to organize code into classes and methods.

Data classes

Data classes are a great way to create immutable classes. While Java's default no-arg constructors are useful, they can be restrictive and make it difficult to reuse your code. Data classes allow you to define a data structure without having to write any boilerplate code.

Data classes are also an alternative way of declaring variables in Kotlin as they don't require the use of var or let statements like in Java (which we'll cover later).