case class的定义
case class 是 Scala 中一种特殊的类，它用于创建不可变的数据容器。
语法如下：
case class ClassName(parameter1: Type1, parameter2: Type2,...)
Set对装入的对象去重
需补充的方法：
-
override def equals(obj: Any): Boolean = { val other = obj.asInstanceOf[Book] other.id == id && other.name == name }
-
override def hashCode(): Int = id }
package caseclass
//Set对装入的对象去重 import scala.collection.mutable
object caseclass1 { class Book(var id:Int, var name:String) { override def equals(obj: Any): Boolean = { val other = obj.asInstanceOf[Book] other.id == id && other.name == name }
override def hashCode(): Int = id
}
def main(args: Array[String]): Unit = { val set1: mutable.Set[Int] = mutable.Set(1, 2)
set1 += 1
set1 += 1
set1 += 1
println(set1)
val book1 = new Book(1, "西游记")
val book2 = new Book(1, "西游记")
println(book1 == book2)
// 定义一个set，它的类型是Book，它可以装入的数据是Book类型
val set2: mutable.Set[Book] = mutable.Set()
set2 += book1
set2 += book2
println(set2)
} }
case class: 样板类
- 可以省略 new
- 属性默认是不可变的。val 修饰
- 它会自动去实现toString, equals, hashCode等方法
object caseclass2 {
case class Student (name:String,age:Int)
def main(args: Array[String]): Unit = {
//val st1 = new Student("芒果",7)
// 1.可以省略new
val st1 = Student("芒果",7)
val st2 = Student("芒果",7)
// 2.默认属性是不可变的，val 修饰
// st1.name = "芒果果"
println(st1)
println(st1 == st2)
}
}
