scala的set

//Set特点：唯一（元素不相同）：无序
//case  class：定义一组数据
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set
    val 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)
    //book1 == book2 ？
    println(book1 == book2)  // true ？ false

    set1 += book1
    set1 += book2
    set1 += book3

    set1.foreach(s => {
      println(s.author)
       })
  }
}

//Set特点：唯一（元素不相同）：无序
//case  class：定义一组数据
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("equals")
//    true
    val ob = obj.asInstanceOf[Book]
    ob.bookName == bookName
  }

  override def hashCode(): Int = bookName.hashCode()

  override def toString: String = s"书名:$bookName \t 作者:$author \t 价格:$price"
}
//1.属性的默认修饰符是val（不可变），说明对象不能改属性
//2.可以省略new
//3.case class  它自动提供：
//           equals方法
//           headCode方法
 case class Student(name:String)
object caseclass{
  def main(args: Array[String]): Unit = {
    val s1 = Student("小花")
    println(s1)

    //定义一个可变set
    val 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)
    println(book1)
    val book2 = new Book("西游记","吴承恩",100)
    val book3 = new Book("西游记","吴承恩",100)
    //book1 == book2 ？
    println(book1 == book2)  // true ？ false

    set1 += book1
    set1 += book2
    set1 += book3

    set1.foreach(s => {
      println(s.author)
       })
  }
}

"C:\Program Files\Java\jdk-17\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2022.2.2\lib\idea_rt.jar=53933:C:\Program Files\JetBrains\IntelliJ IDEA 2022.2.2\bin" -Dfile.encoding=UTF-8 -classpath "E:\untitled\untitled9\out\production\untitled9;C:\Program Files (x86)\scala\lib\scala-library.jar;C:\Program Files (x86)\scala\lib\scala-reflect.jar" caseclass
Student(小花)
书名:西游记  作者:吴承恩  价格:100.0
true
吴承恩

进程已结束,退出代码0

原文地址：https://blog.csdn.net/2301_81557172/article/details/143745830

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