如何使用Kotlin Flow从异步回调中发出数据？ [英] How to emit data from an asycnhronous callback using Kotlin Flow?

问题描述

我开始学习Kotlin Flow和Coroutine，但我不知道如何使下面的代码工作。我做错了什么？

interface MessagesListener {
    fun onNewMessageReceived(message: String)
}

fun messages(): Flow<String> = flow {

    val messagesListener = object : MessagesListener {
        override fun onNewMessageReceived(message: String) {

            // The line below generates the error 'Suspension functions can be called only within coroutine body'

            emit(message)
        }
    }

    val messagesPublisher = MessagesPublisher(messagesListener)
    messagesPublisher.connect()
}

推荐答案

我相信您应该能够使用callbackFlow...类似于：

fun messages(): Flow<String> = callbackFlow {

    val messagesListener = object : MessagesListener {
        override fun onNewMessageReceived(message: String) {
            trySend(message)
        }
    }

    val messagesPublisher = MessagesPublisher(messagesListener)
    messagesPublisher.connect()
}

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