Kotlin Tutorial

Kotlin is a modern programming language that runs on the Java Virtual Machine (JVM). Google made it the official language for Android development in 2019. But Kotlin is not just for Android. You can use it for backend servers, desktop apps, and even web development. Watch the Video: Prefer watching? Check out the video version of this tutorial on YouTube. In this tutorial, you will learn what Kotlin is, where it is used, and why so many developers prefer it over Java. You will also write your first Kotlin code. ...

In the previous tutorial, you learned about extension functions. Now let’s learn about scope functions. Kotlin has five scope functions: let, run, with, apply, and also. They execute a block of code on an object and differ in how they refer to the object and what they return. Watch the Video: Prefer watching? Check out the video version of this tutorial on YouTube. These functions are used everywhere in Kotlin code. Understanding them will make your code cleaner and more readable. ...

In the previous tutorial, you learned about sequences. Now let’s learn about coroutines. Coroutines are Kotlin’s way of writing asynchronous code. They let you write code that looks synchronous but runs without blocking threads. Watch the Video: Prefer watching? Check out the video version of this tutorial on YouTube. In this tutorial, you will learn: Suspend functions launch — fire and forget async/await — get a result Dispatchers coroutineScope Structured concurrency Jobs and cancellation Timeouts Practical examples What Are Coroutines? A coroutine is a lightweight thread. You can run thousands of coroutines on a single thread. Unlike threads, coroutines are cheap to create and do not block the operating system thread they run on. ...

In the previous tutorial, you learned what Kotlin is and why developers love it. Now it is time to install Kotlin on your computer and write your first program. Watch the Video: Prefer watching? Check out the video version of this tutorial on YouTube. In this tutorial, you will: Install IntelliJ IDEA (the best IDE for Kotlin) Create a Kotlin project Write and run your first programs Try the Kotlin REPL Use the Kotlin Playground (no installation needed) Option 1: Kotlin Playground (No Installation) If you want to try Kotlin right now without installing anything, go to the Kotlin Playground. ...

In the previous tutorial, you installed Kotlin and wrote your first programs. Now let’s learn about variables and types — the building blocks of every Kotlin program. Watch the Video: Prefer watching? Check out the video version of this tutorial on YouTube. In this tutorial, you will learn: The difference between val and var All basic types in Kotlin How type inference works How to convert between types How to use constants with const val val vs var Kotlin has two keywords for declaring variables: ...

In the previous tutorial, you learned about variables and types. Now let’s learn about null safety — the feature that makes Kotlin truly special. Watch the Video: Prefer watching? Check out the video version of this tutorial on YouTube. NullPointerException (NPE) is the most common crash in Java and many other languages. Tony Hoare, who invented null references in 1965, called it his “billion-dollar mistake”. Kotlin solves this problem at compile time. ...

In the previous tutorial, you learned about null safety. Now let’s learn about functions — the building blocks that organize your code into reusable pieces. Watch the Video: Prefer watching? Check out the video version of this tutorial on YouTube. Kotlin functions are more powerful than Java methods. They support default parameters, named arguments, single-expression syntax, and much more. In this tutorial, you will learn: Regular functions Single-expression functions Default parameters (no more method overloading) Named arguments Varargs Local functions Higher-order functions Extension functions Infix functions Regular Functions A function in Kotlin starts with the fun keyword: ...

In the previous tutorial, you learned about functions. Now let’s learn about control flow — how to make decisions and repeat actions in your code. Watch the Video: Prefer watching? Check out the video version of this tutorial on YouTube. Kotlin’s control flow is similar to Java, but with important improvements. if and when are expressions that return values. when replaces switch and is much more powerful. In this tutorial, you will learn: ...

In the previous tutorial, you learned about control flow. Now let’s learn about classes — the foundation of object-oriented programming in Kotlin. Watch the Video: Prefer watching? Check out the video version of this tutorial on YouTube. Kotlin classes are more concise than Java classes. What takes 50 lines in Java takes 1 line in Kotlin with data classes. In this tutorial, you will learn: Basic classes and properties Constructors (primary and secondary) Inheritance Abstract classes and interfaces Data classes Enum classes Sealed classes Objects and companion objects Basic Class A class in Kotlin has a primary constructor in the class header: ...