Scala：没有continue，break怎么办？

Posted 2020-08-20 yy

scala自身是没有continue，break这两个语法关键词的。

但是实际上我们还是很希望有这两个语法，那么我们是否可以自己实现呢？

• 从官网上搜索，我们可以找到一下关于break的类相关资料：

Breaks extends AnyRef

A class that can be instantiated for the break control abstraction. Example usage:

val mybreaks = new Breaks
import mybreaks.{break, breakable}

breakable {
  for (...) {
    if (...) break()
  }
}

Calls to break from one instantiation of Breaks will never target breakable objects of some other instantiation.

• continue测试：

import util.control.Breaks._

/**
  * Created by Administrator on 2016/11/15.
  */
object MyMain {
  def main(args: Array[String]): Unit = {
    println("Hello World")

    for (index <- 1 to 10) {
      breakable {
        if (index == 6) {
          println("the index is ："+index)
          break()
        }
        else {
          println("hello" + index)
        }
      }
    }
  }
}

 输出结果
Hello World
hello1
hello2
hello3
hello4
hello5
the index is ：6
hello7
hello8
hello9
hello10

Process finished with exit code 0

• break测试：

import util.control.Breaks._

/**
  * Created by Administrator on 2016/11/15.
  */
object MyMain {
  def main(args: Array[String]): Unit = {
    println("Hello World")
    breakable {
      for (index <- 1 to 10) {
        if (index == 6) {
          println("the index is ：" + index)
          break()
        }
        else {
          println("hello" + index)
        }
      }
    }
  }
}

 或者

import util.control.Breaks._

/**
  * Created by Administrator on 2016/11/15.
  */
object MyMain {
  def main(args: Array[String]): Unit = {
    println("Hello World")
    for (index <- 1 to 10) {
      if (index == 6) {
        println("the index is ：" + index)
        break
      }
      else {
        println("hello" + index)
      }
    }
  }
}

 输出结果

Hello World
hello1
hello2
hello3
hello4
hello5
the index is ：6

 

参考资料：scala break & continue http://www.cnblogs.com/rollenholt/p/4119105.html