scala continue，break 详解

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