Kotlin

Kotlin is a modern, pragmatic programming language developed by JetBrains. Designed to be fully interoperable with Java while being more concise and safer, Kotlin has become the preferred language for Android development and is increasingly popular for server-side applications.

History & Origins

Kotlin was born from JetBrains’ real-world experience. As the creators of IntelliJ IDEA and other developer tools, JetBrains engineers worked extensively with Java and understood its pain points intimately.

In 2010, JetBrains began developing a new language to address Java’s verbosity while maintaining full compatibility with the existing JVM ecosystem. The language was named after Kotlin Island near St. Petersburg, Russia, where many JetBrains developers are based—a nod to Java being named after the Indonesian island.

The Problem Kotlin Solves

Java, despite its maturity and ecosystem, has notable frustrations:

• Verbosity: Getters, setters, equals(), hashCode(), toString() boilerplate
• Null pointer exceptions: The “billion dollar mistake” in software
• Limited type inference: Explicit types everywhere
• No modern features: Lambdas came late, pattern matching still limited

Kotlin addresses these directly:

• Concise syntax: Data classes, property syntax, smart casts
• Null safety: Nullable types are explicit, checked at compile time
• Type inference: val name = "Kotlin" instead of String name = "Kotlin"
• Modern features: Lambdas, extension functions, coroutines, sealed classes

Rise to Prominence

Kotlin’s trajectory changed dramatically in 2017 when Google announced official support for Kotlin on Android at Google I/O. By 2019, Google declared Kotlin the preferred language for Android development.

This endorsement was transformative:

• New Android documentation is Kotlin-first
• Official samples and codelabs use Kotlin
• Jetpack libraries are designed with Kotlin in mind
• Jetpack Compose (modern Android UI) is Kotlin-only

Why Kotlin Succeeded

1. 100% Java interoperability: Call Java from Kotlin and vice versa, use existing libraries
2. Gradual adoption: Convert file by file, not all at once
3. Google’s endorsement: Official Android support legitimized the language
4. JetBrains backing: Created by tooling experts, excellent IDE support
5. Pragmatic design: Focused on solving real problems, not academic purity
6. Null safety: Eliminates entire categories of bugs at compile time

Kotlin Multiplatform

Beyond the JVM, Kotlin now targets multiple platforms:

• Kotlin/JVM: Server-side, Android, desktop applications
• Kotlin/JS: Compile to JavaScript for web development
• Kotlin/Native: Compile to native binaries (iOS, embedded, WebAssembly)
• Kotlin Multiplatform: Share code across platforms while keeping native UIs

Kotlin Multiplatform Mobile (KMM) allows sharing business logic between Android and iOS apps while writing platform-specific UI code.

Modern Kotlin

Kotlin 2.0 (2024) brought the new K2 compiler:

• Faster compilation: Up to 2x speed improvement
• Better IDE support: Faster code analysis and completion
• Foundation for future features: Enables language evolution

Key language features:

• Coroutines: Lightweight concurrency without callback hell
• Sealed classes/interfaces: Exhaustive when expressions
• Inline classes: Zero-overhead type wrappers
• Extension functions: Add methods to existing classes
• DSL capabilities: Build type-safe domain-specific languages

Kotlin vs. Java

Java has been catching up with records, pattern matching, and virtual threads, but Kotlin remains more concise and expressive for most use cases.

The Kotlin Community

Kotlin has a welcoming, pragmatic community focused on solving real problems. JetBrains actively engages through:

• KotlinConf: Annual conference
• Kotlin Slack: Active community discussion
• KEEP: Kotlin Evolution and Enhancement Process

The language continues to evolve based on community feedback while maintaining backward compatibility.