caseclass

一： set对装入的对象进行去重

import scala.collection.mutable
object class22 {
  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 = scala.collection.mutable.Set(1,2)
    set1 += 1
    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)
  }
}

二：case class与普通class的区别

case class: 样板类

1. 可以省略 new
2. 属性默认是不可变的：val 修饰
3. 它会自动去实现toString, equals, hashCode等方法

scala
 
object class23 {

 case class Student(name:String, age:Int)

 def main(args: Array[String]): Unit = {
   // val st1 = new Student("小花", 18)
   val st1 = Student("小花", 18)
   val st2 = Student("小花", 18)
   // 属性默认是不可变的：val 修饰
   // st1.name = "小花"

   println(st1)
   println(st1 == st2)
 }