Kotlin:如何从异步lambda中返回变量? [英] Kotlin: How to return a variable from within an asynchronous lambda?

问题描述

我正在使用加油http 来进行简单的GET请求. 这是我的代码:

I'm using fuel http to make a simple GET request. Here's my code:

fun fetchTweets(): List<Tweet> {

    endpoint.httpGet(listOf("user" to "me", "limit" to 20))
        .responseObject(Tweet.Deserializer()) { _, _, result ->
            result.get().forEach { Log.i("TWEET", it.text) }
            val tweets = result.get().toList() //I want to return this
        }
}

如果我在val tweets下方执行return tweets，则会收到错误消息: return is not allowed here.

If I do return tweets just below val tweets, I get an error: return is not allowed here.

这对我来说很有意义.但是问题仍然存在，我该如何编写一个函数来返回在lambda中创建的变量?在这种情况下，我想返回tweets

The makes sense to me. But the question still remains, how do I write a function that returns the variable created within the lambda? In this case, I want to return tweets

推荐答案

使用 https://github.com/kittinunf/fuel/tree/master/fuel-coroutines 您应该能够编写如下内容(我不熟悉该库，这仅基于README示例):

Using https://github.com/kittinunf/fuel/tree/master/fuel-coroutines you should be able to write something like (I am unfamiliar with the library, this is based just on the README example):

suspend fun fetchTweets(): List<Tweet> {

    val (_, _, result) = endpoint.httpGet(listOf("user" to "me", "limit" to 20))
        .awaitObjectResponseResult(Tweet.Deserializer())
    result.get().forEach { Log.i("TWEET", it.text) }
    return c.get().toList()
}

(不清楚您的问题中c的来源；这可能是result.get().toList()的错字吗?)

(It isn't clear where c comes from in your question; is that maybe a typo for result.get().toList()?)

如果您不熟悉协程，请阅读 https://kotlinlang.org /docs/reference/coroutines/coroutines-guide.html .

If you are unfamiliar with coroutines, read https://kotlinlang.org/docs/reference/coroutines/coroutines-guide.html.

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