kotlin协程flow retry retryWhen（2）

一、retry

import kotlinx.coroutines.flow.*
import kotlinx.coroutines.runBlocking

fun main(args: Array<String>) {
    runBlocking {
        (1..5).asFlow().onEach {
            if (it == 3) {
                println("-")
                throw RuntimeException("error $it")
            }
        }.retry(2) {
            if (it is RuntimeException) {
                println("--")
                return@retry true
            }

            false
        }.onEach {
            println("onEach $it")
        }.catch {
            println("catch $it")
        }.onCompletion {
            println("onCompletion")
        }.collect {
            println("collect $it")
        }
    }
}

onEach 1
collect 1
onEach 2
collect 2
-
--
onEach 1
collect 1
onEach 2
collect 2
-
--
onEach 1
collect 1
onEach 2
collect 2
-
catch java.lang.RuntimeException: error 3
onCompletion

二、retryWhen

import kotlinx.coroutines.flow.*
import kotlinx.coroutines.runBlocking

fun main(args: Array<String>) {
    runBlocking {
        (1..5).asFlow().onEach {
            if (it == 3) {
                println("-")
                throw RuntimeException("error $it")
            }
        }.retryWhen { cause, attempt ->
            if (cause is RuntimeException) {
                println("--")
            }

            attempt < 2
        }.onEach {
            println("onEach $it")
        }.catch {
            println("catch $it")
        }.onCompletion {
            println("onCompletion")
        }.collect {
            println("collect $it")
        }
    }
}

onEach 1
collect 1
onEach 2
collect 2
-
--
onEach 1
collect 1
onEach 2
collect 2
-
--
onEach 1
collect 1
onEach 2
collect 2
-
--
catch java.lang.RuntimeException: error 3
onCompletion

---

import kotlinx.coroutines.flow.*
import kotlinx.coroutines.runBlocking

fun main(args: Array<String>) {
    runBlocking {
        (1..5).asFlow().onEach {
            println("-----")

            var p: Int = (Math.random() * 10).toInt() % 3
            println("it=$it p=$p")

            if (it == p) {
                println("error=$p")
                throw RuntimeException("error-$it")
            } else {
                println("onEach $it")
            }
        }.retryWhen { cause, attempt ->
            if (cause is RuntimeException) {
                println("cause RuntimeException")
            }

            attempt < 2
        }.catch {
            println("catch $it")
        }.onCompletion {
            println("onCompletion")
        }.collect {
            println("collect $it")
        }
    }
}

随机跑一次：

-----
it=1 p=0
onEach 1
collect 1
-----
it=2 p=1
onEach 2
collect 2
-----
it=3 p=0
onEach 3
collect 3
-----
it=4 p=2
onEach 4
collect 4
-----
it=5 p=1
onEach 5
collect 5
onCompletion

再跑：

-----
it=1 p=0
onEach 1
collect 1
-----
it=2 p=2
error=2
cause RuntimeException
-----
it=1 p=0
onEach 1
collect 1
-----
it=2 p=2
error=2
cause RuntimeException
-----
it=1 p=2
onEach 1
collect 1
-----
it=2 p=2
error=2
cause RuntimeException
catch java.lang.RuntimeException: error-2
onCompletion

又跑：

-----
it=1 p=0
onEach 1
collect 1
-----
it=2 p=2
error=2
cause RuntimeException
-----
it=1 p=2
onEach 1
collect 1
-----
it=2 p=1
onEach 2
collect 2
-----
it=3 p=2
onEach 3
collect 3
-----
it=4 p=2
onEach 4
collect 4
-----
it=5 p=2
onEach 5
collect 5
onCompletion

https://zhangphil.blog.csdn.net/article/details/130084723https://zhangphil.blog.csdn.net/article/details/130084723