34.scala编程思想笔记——基于类型的模式匹配

34.scala编程思想笔记——基于类型的模式匹配

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源码下载连接请见第一篇笔记。

可以基于值的模式匹配，还可以按照值的类型来匹配。

例如：

import com.atomicscala.AtomicTest._

 

def acceptAnything(x:Any):String = {

  x match {

    cases:String => "A String: " + s

    case i:Intif(i < 20) =>

      s"AnInt Less than 20: $i"

    case i:Int=> s"Some Other Int: $i"

    casep:Person => s"A person ${p.name}"

    case _=> "I don't know what that is!"

  }

}

acceptAnything(5) is

  "An IntLess than 20: 5"

acceptAnything(25) is "Some Other Int: 25"

acceptAnything("Some text") is

"A String: Some text"

 

case class Person(name:String)

val bob = Person("Bob")

acceptAnything(bob) is "A person Bob"

acceptAnything(Vector(1, 2, 5)) is

"I don't know what that is!"

执行如下：

An Int Less than 20: 5

Some Other Int: 25

A String: Some text

A person Bob

I don't know what that is!

其中acceptAnything的参数类型Any.

Any 允许任何类型的参数。

Match表达式会查找String,Int或我们自己的类型Person.

注意下划线作用是通配符，用来匹配任何值都不匹配的对象。