scala中的递归调用 objectfuture1{ def main（参数：数组[字符串]）：单位={ def getexecute（i:Int）{ println（“开始线程”+i） 线程睡眠（1000L） println（“螺纹末端”+i） } 变量n=10 println（“heelo”+n） def execute_future（n:Int）：单位=未来{ println（“你好”） if（n

这里是一个递归实现的示例，它最接近您的原始代码

//使用Scala 2.12（对于2.11，将Future.unit替换为Future.successful（（））

---

Future.unit.flatMap{…}

和

Future{…}

之间有什么区别？也许这不是正确的问题…但是为什么

Future.unit.flatMap

是必要的？

Future{}

是

Future.unit.map

。我们需要的是

flatMap

来“递归”。有关样式的详细信息，请阅读此文档：

object future1 {
    def main(args: Array[String]): Unit = {
        def getexecute(i:Int){
            println("start thread "+i)
            Thread.sleep(1000L)
            println("end of thread "+i)
        }       
        var n=10
        println("heelo"+n)
        def execute_future(n:Int):Unit = Future{
            println("hello")
            if(n<1){
                println("heelo")
                1
            }           
            else{
                println("get into future")
                getexecute(n)
                execute_future(n-1)
            }
        }
    }
}

object future1 {
    import scala.concurrent._
    import scala.concurrent.duration._
    import ExecutionContext.Implicits._
    def main(args: Array[String]): Unit = {
        def getexecute(i:Int){
            println("start thread "+i)
            Thread.sleep(1000L)
            println("end of thread "+i)
        }       
        def execute_future(n:Int):Future[Int] = Future.unit flatMap { _ =>
            println("hello")
            if(n<1) {
                println("heelo")
                Future.successful(1)
            } else {
                println("get into future")
                getexecute(n)
                execute_future(n-1)
            }
        }

        Await.result(execute_future(10), 15.seconds)
    }
}

scala> future1.main(Array())
hello
get into future
start thread 10
end of thread 10
hello
get into future
start thread 9
end of thread 9
hello
get into future
start thread 8
end of thread 8
hello
get into future
start thread 7
end of thread 7
hello
get into future
start thread 6
end of thread 6
hello
get into future
start thread 5
end of thread 5
hello
get into future
start thread 4
end of thread 4
hello
get into future
start thread 3
end of thread 3
hello
get into future
start thread 2
end of thread 2
hello
get into future
start thread 1
end of thread 1
hello
heelo