Scrobot Scrobot - 10 days ago 9
Android Question

How to zip few observables in Kotlin language with RxAndroid

Everyone!
I have some problem. I'm a beginer in RxJava/RxKotlin/RxAndroid, and dont understand some features. For Example:

import rus.pifpaf.client.data.catalog.models.Category
import rus.pifpaf.client.data.main.MainRepository
import rus.pifpaf.client.data.main.models.FrontDataModel
import rus.pifpaf.client.data.product.models.Product
import rx.Observable
import rx.Single
import rx.lang.kotlin.observable
import java.util.*


class MainInteractor {

private var repository: MainRepository = MainRepository()

fun getFrontData() {

val cats = getCategories()
val day = getDayProduct()
val top = getTopProducts()

return Observable.zip(cats, day, top, MainInteractor::convert)
}

private fun getTopProducts(): Observable<List<Product>> {
return repository.getTop()
.toObservable()
.onErrorReturn{throwable -> ArrayList() }

}

private fun getDayProduct(): Observable<Product> {
return repository.getSingleProduct()
.toObservable()
.onErrorReturn{throwable -> Product()}

}

private fun getCategories(): Observable<List<Category>> {
return repository.getCategories()
.toObservable()
.onErrorReturn{throwable -> ArrayList() }
}

private fun convert(cats: List<Category>, product: Product, top: List<Product>): FrontDataModel {

}
}


Then I'm use MainInteractor::convert Android studio tell me next

enter image description here

I tried a lot of variant and tried to understand what does it want, but no success. Help me please... Best Regards.

Answer

Just replace function reference with lambda:

return Observable.zip(cats, day, top, { c, d, t -> convert(c, d, t) })

And don't forget to declare function's return type explicitly:

fun getFrontData(): Observable<FrontDataModel> {
    ...