Summary - Reflection
- Kotlin course
- Advanced
- Lesson 66/83
- 5 min
Combine KClass, KProperty and call to write a serialization framework.
Summary - Reflection
In this group you saw the reflection tools: class info with KClass, property access with KProperty, function info with KFunction, dynamic calling with call and metadata with annotations.
This lesson includes a small task that combines three of them: you will take a class's KClass reference and print its simpleName and members.size. This pattern brings together the foundation of reflection.
Practice Summary: inspect Person KClass
Define class Person(val name: String, val age: Int). In main take val kc = Person::class and write first println(kc.simpleName), then println(kc.members.size).
Starter code
// Person class: name and age properties
// in main take kc, print its name and member countSample solution
class Person(val name: String, val age: Int)
fun main() {
val kc = Person::class
println(kc.simpleName)
println(kc.members.size)
}Expected output
Person 5
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Which method calls a function at runtime?
- call Correct answer
- let
- apply
- also
Explanation: call invokes a KFunction.
2 Match the reflection tools
| Term | Meaning |
|---|---|
KClass |
Class info |
KProperty |
Property access |
KFunction |
Function info |
annotations |
Metadata |
3 Complete the simpleName call
val kc = Person::class
println(kc.____)val kc = Person::class
println(kc.simpleName)Explanation: kc.simpleName gives the class name.