马老爷子真牛逼，泛型搞了这么多的上界、下界、ViewBound、ContextBound，开发学的不亦乐乎啊

需求仍然是选择girl.

步骤：

1、新建MyGirl类

class  MyGirl(val name:String,val age:Int,val faceValue:Int){}

2、新建ContexBoundDemo

class ContextBoundDemo[T: Ordering] {//为啥这个地方Ordering后面又不加T了呢？真尼玛诡异  def selectGirl(g1: T, g2: T): T = {    val ord: Ordering[T] = implicitly[Ordering[T]]    if (ord.gt(g1, g2)) g1 else g2  }}

这个地方，我不太理解，为啥Ordering后面就不加T了，之前Ordered全加的，梁东老师讲的不是很透彻，只能靠我再去看书了。

3、新建一个隐式值

package testimplicitimport scalapackage.testfanxing.MyGirl/**  * Created by Germmy on 2018/4/8.  */object MyPreDef {   implicit  object  OrderingGirl extends  Ordering[MyGirl]{    override def compare(x: MyGirl, y: MyGirl): Int = {      if(x.faceValue==y.faceValue){        y.age-x.age      }else{        x.faceValue-y.faceValue      }    }  }}

4、新建main

object ContextBoundDemo {  def main(args: Array[String]) {    import testimplicit.MyPreDef.OrderingGirl    val cbd = new ContextBoundDemo[MyGirl]    val g1=new MyGirl("daya",40,90)    val g2=new MyGirl("erya",39,90)    val res=cbd.selectGirl(g1,g2)    println(res.name)  }}