练习

package caseclass

import scala.collection.mutable.ListBuffer

object classClass03 {

  // 1
  case class Book(id:String, bookName:String, author:String, price:Double)

  def main(args: Array[String]): Unit = {

    val book1 = Book("001", "高效能人士的七个习惯", "韦伯", 50)
    val book2 = Book("002", "沉思录", "皇帝", 20)
    val book3 = Book("003", "自控力", "xx", 3)
    // 2, 3
    val bookList = scala.collection.mutable.ListBuffer(book1, book2, book3)

    val book4 = Book("004", "高效能人士的七个习惯", "韦伯", 10)
    // 4,5
    if(addNewBook(bookList, book4)){
      println("添加成功")
    } else {
      println("图书已经存在，添加失败")
    }

    // 6
    val bookName = "沉思录"
    if(queryBook(bookList, bookName)){
      println(s"<<${bookName}>> 存在！")
    } else {
      println(s"<<${bookName}>> 不存在！")
    }

    // 7,8
    delBook(bookList,bookName)

    // 9
    val orderBookList = bookList.sortBy(_.price).reverse

    // 10
    orderBookList.foreach(ele => {
      println(s"书名：《${ele.bookName}》")
      println(s"作者： ${ele.author}")
      println(s"价格： ${ele.price}")
      println()
    })
  }

  def delBook(bookList: ListBuffer[Book], bookName: String):Boolean = {
    // 检查图书是否存在
    val result = bookList.find(_.bookName == bookName)
    if(result.isDefined){
      bookList -= result.get
      true
    } else {
      false
    }
  }

  def queryBook(bookList: ListBuffer[Book], bookName: String):Boolean = {
    bookList.exists(_.bookName == bookName)
  }

  def addNewBook(bookList: ListBuffer[Book], book: Book):Boolean = {
    // 检查书是否存在
    if(bookList.exists(_.id==book.id)){
      false
    } else {
      bookList += book
      true
    }
  }
}