Scala 中for循环示例

1、代码

package com.yy.enhance

/**
 * Scala for 循环示例
 */
case class Student(name:String,isMale:Boolean,children:Student*)
object ForExpressionTest extends App {
  
  val xx = Student("xx",false)
  val yy = Student("yy",true)
  val zz = Student("zz",false,xx,yy)
  val students = List(xx,yy,zz)
  
  val result = students filter(s => !s.isMale) flatMap(
     s=>(s.children map(child=>(s.name,child.name)))    
  )
  println(result)
  
  //使用for循环
  val forRs = for(s <- students; if !s.isMale; child <- s.children)
      yield(s.name,child.name)
  println(forRs)
}

2、结果

List((zz,xx), (zz,yy))
List((zz,xx), (zz,yy))

有关yield的用法，请参考  Scala 的 yield 例子 (for 循环和 yield 的例子)

3、yield示例

package com.yy.enhance

/**
 * yield使用示例
 */
object ForAndYieldTest extends App {
  
  val rs = for(x <- List(1,2,3);y <- List("xx","yy","zz"))
      yield(x,y)
  println(rs)
}

结果如下：

List((1,xx), (1,yy), (1,zz), (2,xx), (2,yy), (2,zz), (3,xx), (3,yy), (3,zz))