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))