Kotlin中如何等待挂起函数执行完成后再执行其他代码

你当前的实现时序错乱核心原因是loadParticlesWithoutSetCall内部通过AppScope.launch启动了一个独立协程，launch是非阻塞的异步启动逻辑，调用loadParticlesWithoutSetCall后会立刻执行后续代码，根本不会等待协程内部的粒子加载逻辑完成。

最规范的实现方式是通过挂起函数暴露可等待的执行逻辑，不要在工具方法内部私自启动无法追踪的异步协程：

1. 将loadParticlesWithoutSetCall改为挂起函数，移除内部自启动的AppScope.launch包裹，把加载逻辑直接放在挂起函数作用域内：

suspend fun loadParticlesWithoutSetCall() {
    // 清空原有内容
    particlesElem.removeAll()

    // 加载粒子逻辑
    val loadingElem = particlesElem.loading("Fetching particles ...")
    val particles: ParticlesData? = try {
        loader()
    } catch (t: Throwable) {
        errorMessage(t)
        null
    } finally {
        particlesElem.remove(loadingElem)
        toWait = true
    }

    particlesDat = particles
}

2. 将setParticlePicking中依赖加载结果的逻辑放到协程作用域内执行，协程会默认按顺序执行，loadParticlesWithoutSetCall()执行完成前不会自动运行后续代码：

fun setParticlePicking(particlePicking: ParticlePicking) {
    // 请替换为和当前组件生命周期绑定的协程作用域，比如Android页面用lifecycleScope、自定义View用viewScope，不要滥用全局AppScope避免内存泄漏
    lifecycleScope.launch {
        loadParticlesWithoutSetCall()

        // 以下逻辑会严格等待粒子加载完成后执行
        manualParticleMarkers?.forEach {
            imageContainerElem.remove(it)
        }
        currentParticlePicking = particlePicking
        manualParticleMarkers = (particlePicking.pickings[imageID]?.map {
            val marker = ManualParticleMarker(
                it.x, it.y,
                image = imageElem,
                trueHeight = particlesDat!!.imageHeight,
                trueWidth = particlesDat!!.imageWidth,
                h = particlesDat!!.h(0),
                w = particlesDat!!.w(0),
                parentElem = this@ParticlesImage.imageContainerElem
            )
            imageContainerElem.add(marker)
            marker
        } ?: mutableListOf()) as MutableList<ManualParticleMarker>
        placeMarkers()
    }
}

如果你必须保留loadParticlesWithoutSetCall内部启动协程的逻辑，可以让函数返回启动协程的Job对象，在调用处对Job执行join()来等待执行完成：

fun loadParticlesWithoutSetCall(): Job {
    return AppScope.launch {
        // 原有内部加载逻辑完全不变
        particlesElem.removeAll()
        val loadingElem = particlesElem.loading("Fetching particles ...")
        val particles: ParticlesData? = try {
            loader()
        } catch (t: Throwable) {
            errorMessage(t)
            null
        } finally {
            particlesElem.remove(loadingElem)
            toWait = true
        }
        particlesDat = particles
    }
}

// 调用处
fun setParticlePicking(particlePicking: ParticlePicking) {
    boundScope.launch {
        // 等待协程执行完成再走后续逻辑
        loadParticlesWithoutSetCall().join()
        // 后续原有业务逻辑不变
    }
}

注意：不要滥用全局AppScope启动和UI/组件生命周期绑定的协程，否则组件销毁后协程仍在后台运行，极易引发内存泄漏、空指针崩溃。

内容的提问来源于stack exchange，提问作者justinm6