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In Kotlin, type aliases let you give a shorter, more meaningful name to an existing type. They are especially useful when your code has deeply nested generics, function types, or repeated complex class structures. A type alias does not create a new type. It only creates an alternative name for an existing type. Basic syntax […]
In Kotlin, this, super, and @ labels are used to disambiguate which receiver or superclass member you mean, especially in nested scopes, inheritance, and inner classes. 1. this: refer to the current receiver Inside a class, this refers to the current instance of that class. class User(val name: String) { fun printName() { println(this.name) } […]
In Kotlin, the by keyword is used for delegation. It lets one object delegate behavior to another object instead of implementing everything manually. There are two common forms: Interface/class delegation Property delegation 1. Interface delegation If a class implements an interface, it can delegate the implementation of that interface to another object using by. Example […]
In Kotlin, properties can have custom getters and setters by defining get() and/or set(value) directly under the property. var propertyName: Type = initialValue get() { return field } set(value) { field = value } field is the backing field automatically generated by Kotlin when needed. Custom getter class Person( val firstName: String, val lastName: String […]
In Kotlin, sealed classes (and sealed interfaces) let you model a closed, type-safe hierarchy: a fixed set of known subtypes. This is especially useful for things like UI state, results, commands, events, and domain-specific alternatives. Basic idea A sealed class restricts which classes can inherit from it. sealed class Result data class Success(val data: String) […]
In Kotlin, enum class is used for a fixed set of constants. Enums can have: simple constants constructor parameters / associated data properties functions overridden behavior per constant companion object utilities implemented interfaces Basic enum enum class Direction { NORTH, SOUTH, EAST, WEST } Usage: val direction = Direction.NORTH when (direction) { Direction.NORTH -> println("Going […]
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