module
- Kotlin course
- Advanced
- Lesson 38/83
- 5 min
Learn to define modules with module { }.
The module block
A module in Koin is the block where dependencies are declared. It is created with module { ... }.
Example: val appModule = module { single { Repository() } }. This module provides the Repository class as a singleton. Modules are usually assigned to a val and connected with startKoin { modules(appModule) }. A module can hold several dependencies. Modules can be split by app section; e.g. a network module, a database module.
Module structure
Inside a module each dependency is declared with a single or factory block. Dependencies can reference each other directly.
Example: module { single { Repository() }; single { Service(get()) } }. Here Service takes Repository via get(). get() asks Koin for the relevant type. Modules can be written as independent pieces. The startKoin call can take several modules; Koin merges them all.
Practice Define appModule
Define val appModule = module { }. Inside main, print println("Module ready").
Starter code
// module
// write here
import org.koin.dsl.module
fun main() {
}Sample solution
val appModule = module {
}
fun main() {
println("Module ready")
}Expected output
Module ready
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Complete the module call
val appModule = ____ {
single { Repository() }
}val appModule = module {
single { Repository() }
}Explanation: module opens the dependency block.
2 Match module parts
| Term | Meaning |
|---|---|
module |
Dependency block |
single |
Singleton |
factory |
New each time |
get |
Another dependency |
3 Which is used to get another dependency inside a module?
- fetch()
- get() Correct answer
- find()
- load()
Explanation: get() fetches another dependency.