kotlin协程flow filter map flowOn zip combine（1）

一、flow ,emit,onCompletion,collect

import kotlinx.coroutines.flow.flow
import kotlinx.coroutines.flow.onCompletion
import kotlinx.coroutines.runBlockingfun main(args: Array<String>) {runBlocking {flow {emit("fly")}.onCompletion {println("完成")}.collect {println(it)}}
}

fly
完成

二、函数作为flow

import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.flow
import kotlinx.coroutines.flow.onCompletion
import kotlinx.coroutines.runBlockingfun main(args: Array<String>) {runBlocking {load().onCompletion {println("onCompletion")}.collect {println("collect $it")}}
}fun load() = flow {for (i in 1..3) {emit(i)delay(100)}
}

collect 1
collect 2
collect 3
onCompletion

三、filter

import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.filter
import kotlinx.coroutines.flow.flow
import kotlinx.coroutines.flow.onCompletion
import kotlinx.coroutines.runBlockingfun main(args: Array<String>) {runBlocking {load().filter {it > 3}.onCompletion {println("onCompletion")}.collect {println("collect $it")}}
}fun load() = flow {for (i in 1..5) {emit(i)delay(100)}
}

collect 4
collect 5
onCompletion

四、map，重组改写数据。

import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.filter
import kotlinx.coroutines.flow.flow
import kotlinx.coroutines.flow.map
import kotlinx.coroutines.flow.onCompletion
import kotlinx.coroutines.runBlockingfun main(args: Array<String>) {runBlocking {load().filter {it > 3}.map {"fly-$it"}.onCompletion {println("onCompletion")}.collect {println("collect $it")}}
}fun load() = flow {for (i in 1..5) {emit(i)delay(100)}
}

collect fly-4
collect fly-5
onCompletion

五、flowOn

import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.*
import kotlinx.coroutines.runBlockingfun main(args: Array<String>) {runBlocking {load().flowOn(Dispatchers.IO).onCompletion {println("onCompletion")}.collect {println("collect $it")}}
}fun load() = flow {for (i in 1..5) {emit(i)delay(100)}
}

collect 1
collect 2
collect 3
collect 4
collect 5
onCompletion

六、zip

import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.*
import kotlinx.coroutines.runBlockingfun main(args: Array<String>) {runBlocking {val flow1 = flowOf(1, 2, 3).onEach {delay(100)}val flow2 = flowOf("a", "b", "c").onEach {delay(200)}flow1.zip(flow2) { i: Int, s: String ->"$i-$s"}.onCompletion {println("onCompletion")}.collect {println(it)}}
}

1-a
2-b
3-c
onCompletion

七、combine

import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.*
import kotlinx.coroutines.runBlockingfun main(args: Array<String>) {runBlocking {val flow1 = flowOf(1, 2, 3).onEach {delay(200)}val flow2 = flowOf("a", "b", "c").onEach {delay(100)}flow1.combine(flow2) { i: Int, s: String ->"$i-$s"}.collect {println(it)}}
}

1-a
1-b
1-c
2-c
3-c

八、conflate 合并

import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.*
import kotlinx.coroutines.runBlocking
import kotlin.system.measureTimeMillisfun main(args: Array<String>) {runBlocking {val time = measureTimeMillis {val f = flow {for (i in 1..10) {delay(100)emit(i)}}val result = f.conflate().onEach { delay(501) }println(result.toList())}println(time)}
}

[1, 5, 10]
1686

九、debounce去重

import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.*
import kotlinx.coroutines.runBlockingfun main(args: Array<String>) {runBlocking {flow {emit(1)delay(50)emit(2)delay(40)emit(3)delay(300)emit(4)delay(30)emit(5)delay(700)}.debounce(300).collect{print(it)}}
}

35