带返回值的 Kotlin 协程 [英] Kotlin Coroutines with returning value

问题描述

我想创建一个有返回值的协程方法.

例如)

fun funA() = async(CommonPool) {返回 1}fun funB() = async(CommonPool) {返回 2}有趣的总和(){发射 {val 总计 = funA().await() + funB().await()}}

如果我想在sum方法中返回total，我该怎么做?

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fun sum(): Int {发射 {val 总计 = funA().await() + funB().await()}总回报}

解决方案

要准确返回 Int，你需要跳出协程世界，这就是 runBlocking对于:

fun sum(): Int = runBlocking {funA().await() + funB().await()}

参见 在协程指南中桥接阻塞和非阻塞世界，以及组合挂起函数 了解如果您想使用 sum inside 协程，如何做到这一点.>

I want to create a coroutine method which has returning value.

For example)

fun funA() = async(CommonPool) {
    return 1
}

fun funB() = async(CommonPool) {
    return 2
}

fun sum() {
    launch {
        val total = funA().await() + funB().await()
    }
}

If I want to return total in sum method, how should I do?

like,

fun sum(): Int {
    launch {
        val total = funA().await() + funB().await()
    }   

    return total
}

解决方案

To return exactly Int, you need to get out of the coroutine world and that's what runBlocking is for:

fun sum(): Int = runBlocking {
    funA().await() + funB().await()
}

See Bridging blocking and non-blocking worlds in the coroutine guide, and Composing suspending functions for how to do it if you want to use sum inside coroutines.

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