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scala中的case class

news 2025/7/14 4:03:43

package test_27
//Set的特点：唯一（元素不同）；无序
//case class定义一组数据
case class Book(var bookName:String,var author:String,var price:Double){}
object caseclass {def main(args: Array[String]): Unit = {//定义一个可变setval set1=scala.collection.mutable.Set[Book]()//向Set中添加两条一样的数据val book1=new Book("西游记","吴承恩",100)val book2=new Book("西游记","吴承恩",100)val book3=new Book("西游记","吴承恩",100)println(book1==book2)set1+=book1set1+=book2set1+=book3set1.foreach(s=>{println(s.author)})}}

去掉case还能否去重？

package test_27
//Set的特点：唯一（元素不同）；无序
//case class定义一组数据
//case class Book(var bookName:String,var author:String,var price:Double){
//
//}class Book(var bookName:String,var author:String,var price:Double){//判断是否相等的逻辑bookName相等override def equals(obj: Any): Boolean = {
//    println("equal")
//   trueval ob=obj.asInstanceOf[Book]ob.bookName==bookName}override def hashCode(): Int = bookName.hashCodeoverride def toString: String = s"书名：$bookName\t 作者：$author \t 价格：$price"
}//1.属性的默认修饰是val（不可变），说明定义对象不能改属性
//2.可以省略new
//3.case class它自动提供：
//equals方法
//hashCode方法
//toString方法
case class Student( name:String)
object caseclass {def main(args: Array[String]): Unit = {val s1=new Student("小花")
println(s1)//定义一个可变setval set1=scala.collection.mutable.Set[Book]()//向Set中添加两条一样的数据val book1=new Book("西游记","吴承恩",100)val book2=new Book("西游记","吴承恩",100)val book3=new Book("西游记","吴承恩",100)println(book1==book2)set1+=book1set1+=book2set1+=book3set1.foreach(s=>{println(s.author)})}}