CallbackToSuspend.kt

import ru.tetraquark.kexperiments.callbacktosuspend.SomeJavaApi
import kotlinx.coroutines.*
import kotlin.Exception
import kotlin.coroutines.Continuation
import kotlin.coroutines.resume
import kotlin.coroutines.resumeWithException
import kotlin.coroutines.suspendCoroutine

fun main() = runBlocking {

    val oldJavaApi = SomeJavaApi()

    runDefaultCallback(oldJavaApi)

    println("")

    runSuspendedCallback(oldJavaApi, this)

    oldJavaApi.destroy()
}


suspend fun runDefaultCallback(oldJavaApi: SomeJavaApi) {
    val defaultApiCallback = object : SomeJavaApi.CustomCallback {
        override fun onSuccess(data: String) {
            println("[Thread id: ${Thread.currentThread().id}]\tOld api callback onSuccess: $data")
        }

        override fun onFailure(exception: Exception) {
            println("[Thread id: ${Thread.currentThread().id}]\tOld api callback onFailure: $exception")
        }
    }

    oldJavaApi.successRemoteCall(defaultApiCallback)
    oldJavaApi.failedRemoteCall(defaultApiCallback)

    println("[Thread id: ${Thread.currentThread().id}]\tMain thread is going to sleep.")
    delay(3500)
}

suspend fun runSuspendedCallback(oldJavaApi: SomeJavaApi, coroutineScope: CoroutineScope) {
    val successfulJob = coroutineScope.launch {
        val apiCallResult = suspendCoroutine<String> { continuation ->
            val suspendedCallback = createOldApiSuspendedCallback(continuation)
            oldJavaApi.successRemoteCall(suspendedCallback)
        }
        println("[Thread id: ${Thread.currentThread().id}]\tSuccessful coroutine result: $apiCallResult")
    }

    val unsuccessfulJob = coroutineScope.launch {
        try {
            suspendCoroutine<String> { continuation ->
                val suspendedCallback = createOldApiSuspendedCallback(continuation)
                oldJavaApi.failedRemoteCall(suspendedCallback)
            }
        } catch (exception: Exception) {
            println("[Thread id: ${Thread.currentThread().id}]\tUnsuccessful coroutine result: $exception")
        }
    }

    // Waiting all coroutines
    println("[Thread id: ${Thread.currentThread().id}]\tMain thread is waiting for coroutines.")
    joinAll(successfulJob, unsuccessfulJob)
}

fun createOldApiSuspendedCallback(continuation: Continuation<String>): SomeJavaApi.CustomCallback {
    return object : SomeJavaApi.CustomCallback {
        override fun onSuccess(data: String) {
            println("[Thread id: ${Thread.currentThread().id}]\tSuspended callback onSuccess: resume continuation")
            continuation.resume(data)
        }

        override fun onFailure(exception: Exception) {
            println("[Thread id: ${Thread.currentThread().id}]\tSuspended callback onFailure: " +
                    "resume continuation with exception")
            continuation.resumeWithException(exception)
        }
    }
}