Scala的模式匹配

一：普通的模式匹配

1.概述

2.程序示例（普通的示例）

 1 package ty
 2 
 3 object MatchCaseTest {
 4   def main(args: Array[String]): Unit = {
 5     judgeGrade("B")
 6   }
 7   def judgeGrade(grade:String): Unit ={
 8     grade match {
 9       case "A"=>println("Excellent")
10       case "B"=>println("Good")
11       case "C"=>println("so")
12       case _=>println("bad")
13     }
14   }
15 }

3.效果

4.if守卫

 1 package ty
 2 
 3 object MatchCaseTest {
 4   def main(args: Array[String]): Unit = {
 5     judgeGrade("B","tom")
 6     judgeGrade("E","tom")
 7   }
 8   def judgeGrade(grade:String,name:String ): Unit ={
 9     grade match {
10       case "A"=>println("Excellent")
11       case "B"=>println("Good")
12       case "C"=>println("so")
13       case _ if name=="tom"=>println("very good")
14       case _=>println("bad")
15     }
16   }
17 }

5.效果

二：Array模式匹配

1.模式匹配（Array）

2.程序示例（Array）

 1 package ty
 2 
 3 object ArrayMatch {
 4   def main(args: Array[String]): Unit = {
 5     judge(Array("x1"))
 6     judge(Array("X2","X3","X4"))
 7     judge(Array("caojun","ui"))
 8   }
 9   def judge(arr:Array[String]): Unit ={
10     arr match {
11         //完全匹配
12       case Array("x1")=>println("x1")
13         //个数匹配
14       case Array(a,b,c)=>println(a,b,c)
15         //某一个元素打头
16       case Array("caojun",_*)=>println("caojun start")
17       case _=>println("======")
18     }
19   }
20 }

3.效果

三：List模式匹配

1.模式匹配（List）

2.程序示例

 1 package ty
 2 
 3 object ListMatch {
 4   def main(args: Array[String]): Unit = {
 5     judge(List("ui"))
 6     judge(List("jj","hh","ff"))
 7     judge(List("lao","li"))
 8   }
 9   def judge(list:List[String]): Unit ={
10     list match {
11       case "ui"::Nil=>println("ui")
12       case b1::b2::b3::Nil=>println(b1+","+b2+","+b3)
13       case "lao"::tail=>println("hi lao start")
14       case _=>println("===")
15     }
16   }
17 }

3.效果

四：遍历与模式匹配结合

1.遍历

 1 package ty
 2 
 3 object ForMatch {
 4   def main(args: Array[String]): Unit = {
 5     "hello world" foreach(c=>println(
 6       c match {
 7         case ' ' =>"space"
 8         case ch =>"Char:"+ch
 9       }
10     ))
11   }
12 }

2.效果

五：样例类

1.模式匹配（case class）

2.程序示例（传统）

 1 package ty
 2 class S(name:String,age:Int){
 3   def say=println("hello")
 4 }
 5 object S{
 6   def apply(name: String, age: Int): S = new S(name, age)
 7 }
 8 object TraditionMatch {
 9   def main(args: Array[String]): Unit = {
10     var s=S("zahngsan",20)
11     s.say
12   }
13 }

3.效果

4.程序示例（case class）

 1 package ty
 2 case class R(name:String,age:Int){
 3   def say=println("hi")
 4 }
 5 object CaseClass {
 6   def main(args: Array[String]): Unit = {
 7     var r=R("lisi",32)
 8     r.say
 9   }
10 }

5.效果

六：类模式匹配

1.程序示例，模式匹配（匹配类）　　

 1 package ty
 2 
 3 //定义一个类
 4 class Per
 5 case class TT(name:String,project:String) extends Per{
 6 
 7 }
 8 case class SS(name:String,room:String) extends Per{
 9 
10 }
11 class JudgeClass(){
12   def judge(per:Per){
13     per match {
14       case TT(name,project)=>println(name+","+project)
15       case SS(name,room)=>println(name+","+room)
16       case _=>println("===")
17     }
18   }
19 }
20 object ClassMatch {
21   def main(args: Array[String]): Unit = {
22     var t=TT("tom","en")
23     var s=SS("Bob","202")
24     new JudgeClass().judge(t)
25   }
26 }

3.效果