KMP
- Kotlin course
- Expert
- Lesson 44/47
- 6 min
Write a shared module with Kotlin Multiplatform.
Shared module with KMP
The second lesson adds the Note data class, which represents the shared module of KMP. This class lives in commonMain; every target uses it.
Example: data class Note(val id: Int, val title: String). A data class auto-generates equals, hashCode and copy. This is the basis of the shared data model. In main you create a Note and print its title. In the next lesson you will extend this class with code generation.
Using the Note model
To create a Note you call the constructor: Note(1, "Merhaba"). Properties are accessed with a dot: n.title.
Thanks to data class, two Notes are equal if their fields match. The copy method produces a copy with one field changed: n.copy(title = "Yeni"). This is the safe way to update shared data. In this lesson main creates a Note and prints its title.
Practice Add the Note class
Define data class Note(val id: Int, val title: String). In main, do val n = Note(1, "Merhaba") and write println(n.title).
Starter code
object App {
fun run(): String = "Expert Notes"
}
// add the Note data class (id: Int, title: String)
fun main() {
// create a Note and print its title
}Sample solution
object App {
fun run(): String = "Expert Notes"
}
data class Note(val id: Int, val title: String)
fun main() {
val n = Note(1, "Merhaba")
println(n.title)
}Expected output
Merhaba
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Match the Note parts
| Term | Meaning |
|---|---|
data class Note |
Shared data |
val id |
Identifier |
val title |
Title |
commonMain |
Source set |
2 Which source set does the Note class live in?
Shared data lives in commonMain.- iosMain
- commonMain Correct answer
- jsMain
- androidMain
Explanation: Note lives in commonMain; every target shares it.
3 Complete the Note definition
data class Note(val id: Int, val ____: String)data class Note(val id: Int, val title: String)Explanation: The Note class carries id and title fields.