Question

I m looking to combine 4 StateFlow values and make 1 StateFlow from these. I know already of the combine function like this:

val buttonEnabled = cameraPermission.combine(micPermission) {
    //some logic
}

如何利用4次流动来做到这一点? 当我尝试下文时,我发现错误时,有太多的论点,但综合职能,即,你确实能够增加多达5个流动?

val buttonEnabled = cameraPermission.combine(micPermission, locationPermission, contactsPermission) {

}

Answer 1

而“但联合职能......” 确实说,你能够增加多达5个流动资金?

是 syntax :

combine(流量1, 流量2, 流量3, 流量4){t1, t2, t3, t4 -> resultMapper}.stateIn(cop)

如果你需要5个以上的组合,那么就非常简单地为6个机构树立了自己的榜样:

fun <T1, T2, T3, T4, T5, T6, R> combine(
    flow: Flow<T1>,
    flow2: Flow<T2>,
    flow3: Flow<T3>,
    flow4: Flow<T4>,
    flow5: Flow<T5>,
    flow6: Flow<T6>,
    transform: suspend (T1, T2, T3, T4, T5, T6) -> R
): Flow<R> = combine(
    combine(flow, flow2, flow3, ::Triple),
    combine(flow4, flow5, flow6, ::Triple)
) { t1, t2 ->
    transform(
        t1.first,
        t1.second,
        t1.third,
        t2.first,
        t2.second,
        t2.third
    )
}

Answer 2

您只能使用从Kotlinx.coroutines.flow.Zip.kt的组合功能。

例如。

combine(flow1, flow2, flow3) {f1,f2,f3-> // do something }

Answer 3

如果您需要将多种同类流动结合起来,不论时间长短,

您可使用这一方法制造

class Util {
    companion object {
        fun <T> getMultipleCombinedFlow(vararg flow: Flow<T>, transform: (T, T) -> T): Flow<T> {
            return combineMultiple(flow, 0, null, transform)
        }

        private fun <T> combineMultiple(
            array: Array<out Flow<T>>,
            index: Int = 0,
            combined: Flow<T>? = null,
            transform: (T, T) -> T
        ): Flow<T> {
            if (array.size == 1) {
                return array[0]
            }
            if (index >= array.size)
                return combined!!

            if (combined == null) {
                val result = array[index].combine(array[index + 1], transform)
                return combineMultiple(array, index + 2, result, transform)
            }

            val result = combined.combine(array[index], transform)
            return combineMultiple(array, index + 1, result, transform)

        }
    }
}

Answer 4

Feb 2024
These are the most direct approaches :

operator	description
`combine`	This operator takes multiple Flows and a transformation function as arguments. The transformation function receives the latest values from each flow and combines them into a single value emitted by the resulting flow. Document
`zip`	Similar to combine, but only emits when all input flows have emitted a value. Useful when you need to react to events happening simultaneously across multiple flows. Document

www.un.org/Depts/DGACM/index_french.htm

val flow1 = flow { ... }
val flow2 = flow { ... }

val combinedFlow = combine(flow1, flow2) { value1, value2 ->
    // combine values here
    Pair(value1, value2) 
}

scope.launch {
    combined.collect{
        Log.e("TAG: ","${it.first} , ${it.second}")
    }
}

www.un.org/Depts/DGACM/index_russian.htm

val flow1 = flow { ... }
val flow2 = flow { ... }
val flow3 = flow { ... }

val zippedFlow = flow1.zip(flow2, flow3) { value1, value2, value3 ->
    // combine values here
    Triple(value1, value2, value3)
}

scope.launch {
    zippedFlow.collect { (value1, value2, value3) ->
        // Use the zipped values
        Log.e("TAG: ","${it.first} , ${it.second} , ${it.third}")
    }
}

友情链接