Java rx嵌套异步调用 [英] Java rx nested asychronous calls

问题描述

我现在正在使用java rx库，在flatMap和map的内部调用中遇到问题，由于某些原因，大多数内部调用未完成.

I am working with the java rx library now, I am having problems with the internal calls with flatMap and map, for some reason the most internal call is not been done.

此外，如果我在内部调用中使用suscribe()替换flatMap(在childrenItemsResponse.forEach代码之前)，则该代码将被执行，但执行不同步，这意味着此调用是在主flatMap之后完成的执行完成.

Besides, if I replace the flatMap with suscribe() in the internal call, (before the childrenItemsResponse.forEach code), this code is executed, bat the execution is not synchronous, I mean this call is done after the main flatMap execution finish.

这是我的代码:

override fun getSportList(dCSServiceContext: DCSServiceContext): Single<List<EntityBrowse>> {
        return dCSService.get(dCSServiceContext).flatMap { item ->
            val entityBrowseList = arrayListOf<EntityBrowse>()
            val section = builSection(item?.firstOrNull()!!)
            if (item.firstOrNull()?.collections?.get("NavItems")?.size!! > 0) {
                dCSServiceContext.contentIds = item.firstOrNull()?.collections?.get("NavItems")
                buildNavItems(dCSServiceContext).map { section ->
                    return@map section
                }.map { items ->
                    section.items = items
                    return@map entityBrowseList
                }
            } else {
                Single.just(entityBrowseList)
            }
        }
    } 

问题在buildNavItems方法中出现:

The problem is presented in the buildNavItems, method:

private fun buildNavItems(dCSServiceContext: DCSServiceContext): Single<MutableList<Item>> {
        return dCSService.get(dCSServiceContext).map { itemsResponse ->
            val items: MutableList<Item> = arrayListOf()
            itemsResponse.forEach { item ->
                val transformedItem = buildItem(item!!)
                if (item?.collections?.get("NavItems") != null) {
                    dCSServiceContext.contentIds = item?.collections?.get("NavItems")
                    val childrenItems: MutableList<Item> = arrayListOf()
                    dCSService.get(dCSServiceContext).flatMap { childrenItemsResponse ->
                        childrenItemsResponse.forEach { childrenItem ->
                            val transformedChildrenItem = buildItem(childrenItem!!)
                            childrenItems.add(transformedChildrenItem)
                        }
                        val section = Section("", "", false,childrenItems )
                        val data = Data(section)
                        val children = Children(data)
                        transformedItem.children = children
                        items.add(transformedItem)
                        Single.just(items)
                    }
                } else {
                    val transformedItem = buildItem(item!!)
                    items.add(transformedItem)
                }
            }
            return@map items
            //Single.just(items)
        }
    }

更具体地说，行代码中的dCSService.get(dCSServiceContext).flatMap { childrenItemsResponse ->

More specifically, the in the line code: dCSService.get(dCSServiceContext).flatMap { childrenItemsResponse ->

此代码永远不会执行.

我不确定是什么原因引起的.

I am not sure about what could be the cause of the issue.

提前谢谢！

推荐答案

要激活观察者链，必须进行订阅.您没有订阅以dCSService...开头的观察者链. flatMap()本身将不会订阅其内部可观测对象，除非已订阅了外部可观测链.

To activate an observer chain, there has to be a subscription. You don't subscribe to the observer chain that starts with dCSService.... flatMap() itself won't subscribe to its interior observables until the outer observable chain has been subscribed to.

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