Scala未来 - 初学者查询

Question

下面的代码没有预料到什么。

import scala.concurrent.Future 
import scala.concurrent.ExecutionContext 

object UseFuture extends App 
{ 
    implicit val ec = ExecutionContext.global 
    Future(println { "This should be run in another thread" }) 
    println("Test") 
} 

但我没能看到未来的输出。

import scala.concurrent.Future 
import scala.concurrent.ExecutionContext 

object UseFuture extends App 
{ 
    implicit val ec = ExecutionContext.global 
    Future(println { "This should be run in another thread" }) 
} 

一个快速的解释？

Answer 1

@Thilo是正确的，你的应用程序退出比Future开始执行更快。 基本上，使用Await.result是不是好的做法when you work with Future，所以这个例子只作教育用途:)

import scala.concurrent.{Await, ExecutionContext, Future} 
import scala.concurrent.duration._ 

object UseFuture extends App 
{ 
    implicit val ec = ExecutionContext.global 
    println(s"Current thread: ${Thread.currentThread().getId}") 
    val future = Future(println { s"Thread id in future: ${Thread.currentThread().getId}. This should be run in another thread" }) 

    Await.result(future, 15.seconds) 
    println("Future has been executed") 
}