Scala开关在成功匹配后继续匹配下一个案例 [英] Scala switch which continue matching next cases after successful match

问题描述

如何在scala switch语句中执行一个case block block后执行另一个case块。 （在java中：没有中断的情况）。

How can I do in scala switch statement which after performing one case block start perform another case block. (in java: cases without break).

switch(step) {
    case 0: do something;
    case 1: do something more;
    case 2: etc...;
            break;
    default: do something else;
}

感谢您的帮助！

推荐答案

如果你不能使用 0 | 1 | 2 您可以使用一系列操作作为解决方法，如下所示：

In case you can't use 0 | 1 | 2 you could use a list of actions as workaround like this:

def switch[T](i: T)(actions: (T, () => Unit)*)(default: => Unit) = {
  val acts = actions.dropWhile(_._1 != i).map{_._2}
  if (acts.isEmpty) default
  else acts.foreach{_()}
}

def myMethod(i: Int): Unit = 
  switch(i)(
    0 -> {() => println("do 0")},
    1 -> {() => println("do 1")},
    2 -> {() =>
      println("do 2")
      return // instead of break
    },
    3 -> {() => println("do 3")}
  )(default = println("do default"))


myMethod(1)
// do 1
// do 2

myMethod(3)
// do 3    

myMethod(5)
// do default

这篇关于Scala开关在成功匹配后继续匹配下一个案例的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！