Kotlin

In the previous tutorial, you learned about collections. Now let’s learn about lambdas and higher-order functions. These are some of the most powerful features in Kotlin. A lambda is a function without a name. You already used lambdas with filter, map, and other collection functions. In this tutorial, you will learn how they work in depth. In this tutorial, you will learn: Lambda syntax and the it keyword Trailing lambdas Function types like (Int) -> String Higher-order functions (functions that take or return functions) Function references Closures Inline functions Lambda Syntax A lambda is written between curly braces { }. The arrow -> separates the parameters from the body. ...

In the previous tutorial, you learned about classes. Now let’s learn about collections — one of the most important topics in Kotlin. You will use collections in almost every program you write. Kotlin’s collections are powerful and expressive. You can filter, transform, group, and combine data with just a few lines of code. In this tutorial, you will learn: List, MutableList, Set, and Map filter, map, flatMap groupBy, sortedBy reduce and fold zip and associate Chaining operations together List A List is an ordered collection. listOf creates a read-only list. mutableListOf creates a list you can change. ...

Welcome to Part 2 of the series. You can now build beautiful single-screen apps. But real apps have many screens — a home screen, a detail screen, a settings screen, a profile screen. Navigation is how you move between them. In this tutorial, you will learn everything about Compose navigation: Setting up navigation Creating screens and routes Type-safe navigation with Kotlin Serialization Passing data between screens Bottom navigation bar Nested navigation graphs Back stack management Best practices This is a long tutorial. Take your time. ...

Your app works. But it looks like every other default Compose app — same purple, same fonts, same everything. Theming is how you make your app look like YOUR app. Custom colors, custom fonts, dark mode support — all in one system that applies everywhere automatically. Material 3 (also called Material You) is the design system Google built for modern Android apps. Compose uses it by default. In this tutorial, you will learn how to customize it. ...

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. 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. 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. 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. 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. 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. 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. ...