suspend
runBlocking launch async
runBlocking是主協程，裡面包含了job1與job2二個子協程。
runBlocking會等待job1與job2執行完畢。
launch、async都是同時執行，job2不用等待job1執行完畢才執行。
1
2
3
4
5
6
7
8
9
10
| fun coroutin01() = runBlocking {
val job1 = launch {
delay(200)
println("job1 finished")
}
val job2 = async {
delay(200)
println("job2 finished")
}
}
|
job1 finished
job2 finished
await() 傳回值
語法
async會傳回最後一行執行結果，並讓主協程等待job2子協程執行完畢。
1
2
3
4
5
6
7
8
9
10
11
12
13
14
| fun coroutin01() = runBlocking {
val job1 = launch {
delay(200)
println("job1 finished")
}
val job2 = async {
delay(200)
println("job2 finished")
// 回傳結果
"job2 result"
}
// 印出回傳結果
println(job2.await())
}
|
job1 finished
job2 finished
job2 result
await()執行完才輪其它協程
job1先執行，job1執行完，才輪job2與job3，job2、job3同時執行。(程式碼移動到那一行，就執行)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
| fun coroutin01() = runBlocking {
val job1 = launch {
delay(200)
println("job1 finished")
}
// job1 先執行
job1.await()
val job2 = async {
delay(200)
println("job2 finished")
}
val job3 = async {
delay(200)
println("job3 finished")
}
}
|
join()執行完才輪其它協程
job1先執行，job1執行完，才輪job2與job3，job2、job3同時執行。(程式碼移動到那一行，就執行)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
| fun coroutin01() = runBlocking {
val job1 = launch {
delay(200)
println("job1 finished")
}
job1.join()
val job2 = async {
delay(200)
println("job2 finished")
}
val job3 = async {
delay(200)
println("job3 finished")
}
}
|
逐步執行與同時執行
沒加async是逐步執行
measureTimeMillis()是計算執行時間。
doOne()、doTwo()都是suspend 協程函式。
但在這邊會doOne()執行完，才輪到doTwo()執行。
所以耗時2秒多。
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
| fun coroutin02() = runBlocking {
val time = measureTimeMillis {
val one = doOne()
val two = doTwo()
println("result = ${one + two}")
}
println("total in $time ms")
}
private suspend fun doOne():Int {
// 停1秒
delay(1000)
return 10
}
private suspend fun doTwo():Int {
// 停1秒
delay(1000)
return 20
}
|
result = 30
total in 2022 ms
加async是同時執行
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
| fun coroutin02() = runBlocking {
val time = measureTimeMillis {
val one = async{doOne()}
val two = async{doTwo()}
println("result = ${one.await() + two.await()}")
}
println("total in $time ms")
}
private suspend fun doOne():Int {
delay(1000)
return 10
}
private suspend fun doTwo():Int {
delay(1000)
return 20
}
|
result = 30
total in 1020 ms
await()傳回值錯誤範例
await()放在async{}後面，會導致doOne()執行完畢，doTwo()才能執行，變成逐步執行，而不是同時執行。
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
| fun coroutin02() = runBlocking {
val time = measureTimeMillis {
val one = async{doOne()}.await()
val two = async{doTwo()}.await()
println("result = ${one + two}")
}
println("total in $time ms")
}
private suspend fun doOne():Int {
delay(1000)
return 10
}
private suspend fun doTwo():Int {
delay(1000)
return 20
}
|
result = 30
total in 2024 ms
launch async父類別
launch繼承Job
1
2
3
4
5
| public fun CoroutineScope.launch(
context: CoroutineContext = EmptyCoroutineContext,
start: CoroutineStart = CoroutineStart.DEFAULT,
block: suspend CoroutineScope.() -> Unit
): Job
|
async繼承Deferred，Deferred繼承Job，所以async父類別也是job。
1
2
3
4
5
| public fun <T> CoroutineScope.async(
context: CoroutineContext = EmptyCoroutineContext,
start: CoroutineStart = CoroutineStart.DEFAULT,
block: suspend CoroutineScope.() -> T
): Deferred<T>
|
1
| public interface Deferred<out T> : Job
|
啟動模式的設定
所謂的啟動模式，也就是下面的start參數，async()與launch()都有start
1
2
3
4
5
| public fun CoroutineScope.launch(
context: CoroutineContext = EmptyCoroutineContext,
start: CoroutineStart = CoroutineStart.DEFAULT,
block: suspend CoroutineScope.() -> Unit
): Job
|