Android-使用流创建回调

我试图理解流程，但几乎没有什么事情是我不清楚的。我有一个简单的界面：

interface Operation<T> {
    fun performAsync(callback: (T? , Throwable?) -> Unit)
    fun cancel()
}

---

请您解释一下，如何观察异常（或T值）并在Activity/Fragment中发送/接收异常？

您如何使用密封类

sealed class Operation<out V, out E> {

data class Result<out V> (val data: V) : Operation<V, Nothing>()

data class Error<out E> (val error: E) : Operation<Nothing, E>()

companion object {
    inline fun <V> build(operation : () -> V) : Response<V, Exception> {
        return try {
            Value(operation.invoke())
        } catch (e: Exception) {
            Error(e)
        }
    }
}

fun convert () {
try {
  val carJSON = gson.toJson(carObj)
  //send Car value
} catch (e : Exception) {
  //here I want to send exception and receive it in callback in activity/fragment.
}
}

sealed class Operation<out V, out E> {

data class Result<out V> (val data: V) : Operation<V, Nothing>()

data class Error<out E> (val error: E) : Operation<Nothing, E>()

companion object {
    inline fun <V> build(operation : () -> V) : Response<V, Exception> {
        return try {
            Value(operation.invoke())
        } catch (e: Exception) {
            Error(e)
        }
    }
}

fun someFunction() : Operation<Flow<String>, Exception> {

val flow = callbackFlow<String> { 

val callback = object : someCallback {

       onResult(result: String) {
          offer(result)
       }
       onError(e: Exception) {
          throw e 
       }
}

awaitClose { callback.remove() } //Just an example of a callback

}

return Operation.build { flow }

}

when(someFunction) {

is Operation.Result -> collect(someFunction().data)
is Operation.Error  -> handleErrorAsHoweverYouWant(someFunction().error)

}