Everything you need to know about Kotlin extensions

Kotlin extensions are a powerful feature that allows developers to add new functionalities to existing classes without modifying or inheriting from them, thereby making it possible to adapt third-party and built-in classes to specific needs. This capability extends to adding functions and properties to classes and companion objects, with extensions being resolved statically at compile-time rather than runtime. Defined at the top-level scope, they can be imported and used like any external dependency, even on nullable types, making them versatile for handling null safety. Advanced use cases include defining extensions within other classes, allowing access to multiple implicit receivers, and the ability to extend companion objects. Real-world examples demonstrate how extensions can simplify tasks such as date manipulation or retrieving elements from a list, showcasing their ability to streamline code and enhance functionality without the need for boilerplate code. As a tool that every Kotlin developer should master, extensions enable the customization and adaptation of classes efficiently, enhancing productivity and code maintainability.