Java通用于Kotlin泛型。 从方法返回泛型

Question

Trying to convert a project from Java to Kotlin.

I got stuck on a method that returns ObservableTransformer from RXJava 2

Java

protected <T> ObservableTransformer<T, T> onNetworkError() {
    return observable -> observable
            .doOnError(throwable -> networkError.setValue(throwable));
}

Converting this using intellij ide throws an error.

Java to Kotlin using ide

protected fun <T> onNetworkError(): ObservableTransformer<T, T> {
    return { observable ->
        observable
                .doOnError({ throwable -> networkError.setValue(throwable) })
    }
}

Does anyone have an idea to convert the above Java code to Kotlin?

Thanks in advance

Answer 1

Your code is returning a function which accepts observable of unknown type and returns an Observable object.

The lambda expression you need should be like this:

protected fun <T> onNetworkError(): ObservableTransformer<T, T> {
    return ObservableTransformer { observable ->
        observable
                .doOnError({ throwable -> networkError.setValue(throwable) })
    }
}

Answer 2

Additionally to BakaWaii's response from above, you can further simplify the code as follows:

protected fun <T> onNetworkError(): ObservableTransformer<T, T> {
    return ObservableTransformer {
        it.doOnError { networkError.setValue(it) }
    }
}

However, having two different it s might be confusing, so you might want to leave one of them as an explicit parameter.