Kotlin: Convert Async APIs into Sync

KotlinAysncToSync.kt

class Worker {
    /*Async API*/
    fun doSomething(listener: Listener, throwError: Boolean) {
        when (throwError) {
            true -> {
                Thread.sleep(3000)
                listener.onError(Exception("Just a random exception..."))
            }
            else -> {
                Thread.sleep(3000)
                listener.onSuccess("Success")
            }
        }
    }

    interface Listener {
        fun onSuccess(msg: String)
        fun onError(e: Exception)
    }
}

/**
 * Converting Async API into Sync.
 * Here is the magic happens though Kotlin's [suspendCoroutine].
 * [suspendCoroutine] return a success state or exception.
 *
 * @param throwError [Boolean].
 *
 * @return [String].
 */
suspend fun Worker.doSomethingSync(throwError: Boolean): String {
    return suspendCoroutine {
        doSomething(object : Worker.Listener {
            override fun onSuccess(msg: String) {
                it.resume("Success")
            }

            override fun onError(e: Exception) {
                it.resumeWithException(e)
            }

        }, throwError)
    }
}

class Tester {
    fun test() {
        val worker = Worker()
        /*Async Operation*/

        /*Callback to get notified regarding the result*/
        val listener = object : Worker.Listener {
            override fun onSuccess(msg: String) {
                println(msg)
            }

            override fun onError(e: Exception) {
                e.printStackTrace()
                println(e.message)
            }
        }
        /*Do some work, don't throw exception*/
        worker.doSomething(listener, false)
        /*Do some work, throw exception*/
        worker.doSomething(listener, true)


        /*Async to Sync Operation*/
        CoroutineScope(Dispatchers.Main).launch {
            try {
                /*Do some work, don't throw exception*/
                println(worker.doSomethingSync(false))
                /*Do some work, throw exception*/
                println(worker.doSomethingSync(true))
            } catch (e: Exception) {
                e.printStackTrace()
                println(e.message)
            }
        }
    }
}