scala 使用期货和 Thread.sleep
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Using futures and Thread.sleep
提问by ctamisier
By executing this scala code, I don't have any output in the console. (I don't really understand what is happening)
通过执行此 Scala 代码，我在控制台中没有任何输出。（我真的不明白发生了什么）
If I remove Console.println("Console.println OK!")=> everything seems fine.
如果我删除Console.println("Console.println OK!")=> 一切似乎都很好。
If I remove Thread.sleep(2000)=> everything seems fine.
如果我删除Thread.sleep(2000)=> 一切似乎都很好。
Do you have any ideas about this ? Thank you very much!
你对此有什么想法吗？非常感谢你！
Clément
克莱门特
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.duration._
import scala.concurrent.{Await, Future}
import scala.language.postfixOps
object ScalaFuture {
def main(args: Array[String]) {
val f: Future[String] = Future {
Thread.sleep(2000)
"future value"
}
f.onSuccess {
case s => {
Console.println("Console.println OK!")
System.out.println("System.out.println OK!")
}
}
Await.ready(f, 60 seconds)
}
}
回答by dk14
Your await is waiting for future to complete, which is done after 2 seconds, but it doesn't wait for onSuccesshandler, which executes in another thread (similar to future), but after Await.ready(f, 60 seconds), so process exits earlier than you print something. To process it correctly - create new future for onComplete:
您的 await 正在等待 future 完成，这会在 2 秒后完成，但它不会等待onSuccess在另一个线程中执行的处理程序（类似于 future），而是在 之后Await.ready(f, 60 seconds)，因此进程在您打印某些内容之前退出。正确处理它 - 为以下创造新的未来onComplete：
val f: Future[String] = Future {
Thread.sleep(2000)
"future value"
}
val f2 = f map { s =>
println("OK!")
println("OK!")
}
Await.ready(f2, 60 seconds)
println("exit")
Results for Await.ready(f, ...):
结果Await.ready(f, ...)：
exit
OK!
OK!
Results for Await.ready(f2, ...):
结果Await.ready(f2, ...)：
OK!
OK!
exit
回答by Ray Standers
Just put readLine() in your code.
只需将 readLine() 放入您的代码中。
