leomindez / kotlin-dagger-example

Example of Android project showing integration with Kotlin and Dagger 2

kotlin-dagger-example

This project demonstrate how to setup an Android Project with Kotlin and Dagger 2.

It's based on Dagger 2 example

##Known issues/limitations

1. Kotlin compiler does not allow $ sign in class names. So you can't use Dagger's generated classes that use $. There is an issue reported KT-6444. Dagger 2 is also going to remove $ from their naming conventions, see issue
2. Classes and interfaces that Dagger use for generating implementations must be kept in Java. If it's moved to Kotlin it won't be generated e.g. AndroidModule, ApplicationComponent
3. Dagger's field injection is not working within Kotlin files.

This will not work:

Inject var locationManager: LocationManager? = null

Fortunately, setter injection works for Kotlin and syntax is simple:

var locationManager: LocationManager? = null
[Inject] set

How to use @Named property qualifier

If you are going to use multiple @Provides for the same type you would expect injecting property like this:

var typeface: Typeface? = null
[Inject Named("bold")] set

Unfortunatelly, it won't work. It will not even compile.

Proper way is

var typeface: Typeface? = null
[Inject] set([Named("bold")] value) {
    $typeface = value
}

Be careful where you call Dagger's inject(this) method. If you do it from the class constructor it won't work becasue after injection, property is initialised with null value. If you do it in Activity or Fragment, onCreate() will be just fine. If not, you have to create your own function and call it explicitly wherever you initialise your class. For some more datails see issue KT-6740