KClass

Learn class info with ::class and KClass.

Class info with KClass

KClass holds the runtime info of a class. The ::class syntax gives you a KClass reference. It provides info about members, constructors and supertypes.

Example: val kc = String::class; println(kc.simpleName). This prints String. Use kc.isData to check if it is a data class and kc.members to list members. Reflection inspects types at runtime.

simpleName and isData

The simpleName property of KClass gives the short name of the class. Flags like isData, isAbstract and isSealed describe the class nature.

Example: data class User(val name: String). User::class.isData returns true. User::class.simpleName gives "User". These flags let you branch on the type structure at runtime.

Exercise Print the Person class name

Define class Person(val name: String). In main print the result of Person::class.simpleName with println.

Show example solution

class Person(val name: String)

fun main() {
    println(Person::class.simpleName)
}

Test yourself

Which syntax gets a KClass reference of a class?
- getClass()
- .class
- classOf<>()
- ::class
Show answer

::class — In Kotlin ::class gives a KClass reference.

Complete the KClass reference

val kc = String____

Show answer

val kc = String::class

Match the KClass parts

String::class

KClass reference
simpleName

Type name
isData

Data class flag
members

Members

Next lesson: KProperty

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies