match表达式
// 正则匹配 val pattern = "([0-9]+) ([a-z]+)".r; "741258933 hadoop" match { case pattern(num,item) => println(num+":"+item) }
输出结果:741258933:hadoop
数组匹配
def match_array(arr:Any) = arr match{ case Array(0) => println("Array:0" ) case Array(x,y) => println("Array:x="+x+",y="+y ) case Array(0,_*) => println("Array:..." ) case _ => println("something else" ) } match_array(Array(0)) match_array(Array(0,1)) match_array(Array(0,1,2,3,4,5)) match_array(Array("one","two","three"))
输出结果:
Array:0
Array:x=0,y=1
Array:...
somethingelse
case class匹配
Scala的case class使得对对象进行模式匹配变得非常方便,简单的来说,Scala的case class就是在普通的类定义前加case这个关键字,然后你可以对这些类来模式匹配。
abstract class Person case class Student(age:Int) extends Person case class Worker(age:Int,salary:Double) extends Person case object Shared extends Person /** * 1、声明case class 每个成员都会默认生成val,如age:Int * 2、每个case class 都会有伴生对象,每个伴生对象都会有自己case class的具体对象 * 3、模式匹配的时候,可以从case class提取内容,提取方法从apply中。 */ object case_class_object { def main(args: Array[String]): Unit = { def caseOps(person:Person) = person match{ case Student(age) => println("I am " + age + " years old"); case Worker(_,salary) => println("Wow,I got "+salary) case Shared => println("no property..."); } caseOps(Student(19)) caseOps(Worker(19,4000)) caseOps(Shared) val worker = Worker(29,3000); val worker2 = worker.copy(salary = 5000); val worker3 = worker.copy(age = 31); } }
输出结果:
Iam 19 years old
Wow,Igot 4000.0
noproperty...