类型不匹配。 必需：找不到：回调<*>

Question

In my android project:

import retrofit2.Call
import retrofit2.Callback

    fun getAdvertising(callback: Callback<List<Advertising>>) {
        val call = tangoRestClient.advertising
        executeAsync(call, callback)
    }

    private fun executeAsync(call: Call<*>, callback: Callback<*>) {
        call.enqueue(callback)  // compile error
    }

But I get compile error:

> Task :app:generateDebugSources
> Task :app:validateSigningDebug

> Task :transport:compileDebugKotlin FAILED
e: \TransportService.kt: (127, 14): Out-projected type 'Call<*>' prohibits the use of 'public abstract fun enqueue(p0: Callback<T!>!): Unit defined in retrofit2.Call'

FAILURE: Build failed with an exception.

Answer 1

Yep, the type parameter of Call and Callback should be the same. You have to write your executeAsync function for example like this:

private fun <T> executeAsync(call: Call<T>, callback: Callback<T>) {
    call.enqueue(callback)  // no compile error
}

It will guarantee that type parameters are the same