简单来说，Scala的case class就是在普通的类定义前加case关键字，然后你可以对这些类来模式匹配。
case class带来的最大的好处是它们支持模式匹配。
简单的case class 模式匹配代码示例：
package com.yl.Scala
abstract class Person //定义抽象类Person
case class Student(age: Int) extends Person //case类Student
case class Worker(age: Int, salary: Double) extends Person
case object Shared extends Person //case 单例对象
object CaseClass {
def main(args: Array[String]){
def caseTest(person: Person) = person match{
case Student(age) => println("I am " + age + " years old.") //与Student类对象类型进行匹配
case Worker(_, salary) => println("I got only " + salary + " ...")//与Worker类对象类型进行匹配
case Shared => println("单例对象Shared，直接用本身进行传递") //与单例对象Shared对象类型进行匹配
}
caseTest(Student(24))
caseTest(Worker(34, 1000))
caseTest(Shared)
val worker1 = Worker(24, 3800) //case class 实例化可免去new
val worker2 = Worker(25, 4100)
val worker3 = Worker(26, 8000)
val worker4 = Worker(27, 9500)
caseTest(worker1)
caseTest(worker2)
caseTest(worker3)
caseTest(worker4)
}
}运行结果:
I am 24 years old.
I got only 1000.0 ...
单例对象Shared，直接用本身进行传递
I got only 3800.0 ...
I got only 4100.0 ...
I got only 8000.0 ...
I got only 9500.0 ...Scala 中嵌套的case class的模式匹配示例：
package com.yl.Scala
abstract class Item
case class Book(description : String, price: Double) extends Item
case class Bundle(description : String, price: Double, items: Item*) extends Item //含有嵌套类类型Item
object CaseClassAdvanced {
def main(args: Array[String]){
def caseTest(thing: Item) = thing match{
//Bundle
case Bundle(_, _, art @Book(_, _), rest @ _*)
=> println(art.description + " price: " + art.price + "$") //嵌套Book类实例对象art
//Book
case maths @Book(_, _) => println(maths.description + " price: " + maths.price + "$")
case _ => println("something else.")
}
caseTest(Bundle("sth.", 34.22, Book("Book name : Art", 24.45)))
caseTest(Book("Book name : Maths", 55.33))
}
}运行结果：
Book name : Art price: 24.45$
Book name : Maths price: 55.33$