Collectives™ on Stack Overflow

Find centralized, trusted content and collaborate around the technologies you use most.

Teams

Q&A for work

Connect and share knowledge within a single location that is structured and easy to search.

I try to implement Dagger2 into my Kotlin project but I have problems with the @Inject annotation.

In Java it looks like this and this works fine:

public class FooActivity extends Activity {
    @Inject
    @Named("accessTokenObservable")
    public Flowable<Optional<AccessToken>> accessTokenObservable;
    @Override
    protected void onCreate(@Nullable final Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        App.getGraph().inject(this);
But how I have to write the @Inject line in Kotlin?
When I use this one:
@Inject
@Named("accessTokenObservable")
var accessTokenObservable: Flowable<Optional<AccessToken>>? = null
I get this error message:
Error:Dagger does not support injection into private fields
If I use lateinit:
@Inject
@Named("accessTokenObservable")
lateinit var accessTokenObservable: Flowable<Optional<AccessToken>>
I get this error message:
Error:Flowable<Optional<AccessToken>> cannot be provided without
an @Provides- or @Produces-annotated method.
What is the right syntax to inject something in Kotlin?
lateinit var presenter: ItemsPresenter
override fun onCreate(savedInstanceState: Bundle?) {
    AndroidInjection.inject(this)
    super.onCreate(savedInstanceState)
Without any problems
                Slightly off-topic nitpick but according to google.github.io/dagger/android.html  ''AndroidInjection.inject(this);'' should be called before ''super.onCreate(savedInstanceState);''
– activout.se
                Oct 9, 2017 at 8:46
You have to change your injection code like this:
@field:[Inject Named("accessTokenObservable")]
lateinit var accessTokenObservable: Flowable<Optional<AccessToken>>
, and it will be fixed.
Do you provide Flowable<Optional<AccessToken>> accessTokenObservable somewhere  in your code? 
If not 
Error:Flowable<Optional<AccessToken>> cannot be provided without
an @Provides- or @Produces-annotated method. can be produced. Because you are trying to inject object without provide it.
In this case you need to provide in your injector class:
@Provide
@Named("accessTokenObservable")
fun provideAccessTokenObservable : Flowable<Optional<AccessToken>>{
    return yourAccessTokenObservable
then you need to inject your object in your activity
@Inject
@Named("accessTokenObservable")
lateinit var accessTokenObservable: Flowable<Optional<AccessToken>>
        
Thanks for contributing an answer to Stack Overflow!
Please be sure to answer the question. Provide details and share your research!
But avoid …
Asking for help, clarification, or responding to other answers.
Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.