运用集合来做一个DVD管理器（全代码）

package DVD;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
import java.util.Scanner;
import java.util.TreeSet;

class Dvd{
   String name;
   String date;
   int state;
   int count;

   public Dvd(String name,int state,String date,int count){
       this.name = name;
       this.date = date;
       this.state = state;
       this.count = count;
   }

   public String toString() {
       // TODO Auto-generated method stub
       if(state==1){
           return "可借 "+"《"+name+"》 "+date;
       }
       return "不可借 "+"《"+name+"》 "+date;
   }
}

//比较器
class DVDCompar implements Comparator<Dvd>{
   @Override
   public int compare(Dvd o1, Dvd o2) {
       // TODO Auto-generated method stub
       return o2.count-o1.count;
   }
}

class DvdMgr{

   List<Dvd> list = new ArrayList<Dvd>(); //创建一个list集合

   public void initial(){
       Dvd dvd = new Dvd("罗马假日", 0, "2016-12-1", 20);
       Dvd dvd2 = new Dvd("浪漫满屋", 1, " ", 30);
       Dvd dvd3 = new Dvd("风声鹤唳", 1, " ", 10);

       // 初始化集合
       list.add(dvd);
       list.add(dvd2);
       list.add(dvd3);
   }

// 菜单
   public void returnMenu(){
       System.out.println("******欢迎使用迷你DVD管理器******");
       System.out.println("****************************");
       System.out.println("******* 0.借出排行榜 **********");
       System.out.println("******* 1.新增DVD **********");
       System.out.println("******* 2.查看DVD **********");
       System.out.println("******* 3.删除DVD **********");
       System.out.println("******* 4.借出DVD **********");
       System.out.println("******* 5.归还DVD **********");
       System.out.println("******* 6.退       出    **********");
       System.out.println("**************************** ");

       System.out.print("请选择：");
       Scanner scanner = new Scanner(System.in);
       int input = scanner.nextInt();

       switch (input) {
       case 0:
           Top();
           break;
       case 1:
           add();
           break;
       case 2:
           search();
           break;
       case 3:
           delete();
           break;
       case 4:
           lend();
           break;
       case 5:
           returnDVD();
           break;
       case 6:
           System.out.println("*****欢迎下次继续使用！*****");
           break;
       default:
           System.out.println("输入错误，这个功能正在完善中....");
           break;
       }
   }
//添加
   public void add(){
       System.out.println("欢迎进入新增页面！");
       System.out.print("请输入DVD名称： ");
       Scanner scanner = new Scanner(System.in);
       String inputName = scanner.next();
       int num = list.size();

       Dvd dvd = new Dvd(inputName, 1, " ", 0);
       list.add(dvd);

       if(list.size()>num){
           System.out.println("新增《"+inputName+"》成功");

           returnCom();

       } else {
           System.out.println("新增失败");
       }
   }
//查找
   public void search(){
       System.out.println("********欢迎进入查找页面******** ");
       System.out.println("序号状态 "+"名称 "+"借出日期");
       for(int i = 0; i < list.size(); i++){
           System.out.println((i+1)+" "+list.get(i));
       }

       returnCom();
   }
//删除
   public void delete(){
       System.out.println("*****欢迎进入删除页面*****");
       while(true){
           System.out.print("请输入DVD名称：");
           Scanner scanner = new Scanner(System.in);
           String input = scanner.next();

           boolean b = false;
           for(int i = 0; i < list.size(); i++){
               if(list.get(i).name.equals(input)){
                   list.remove(i);
                   b = true;
               }
           }

           if(b == true){
               System.out.println("删除《"+input+"》成功");
               returnCom();
           }else {
               System.out.println("没有这个DVD,请重新输入！");
           }
       }
   }

// 借出
   public void lend(){
       System.out.println("******欢迎进入借出页面*****");
       System.out.print("请输入DVD名称：");
       Scanner scanner = new Scanner(System.in);
       String input = scanner.next();

       boolean b = false;
       for(int i = 0; i < list.size(); i++){
           Dvd dvd = list.get(i);
           if(dvd.name.equals(input)){
               b = true;
               if(dvd.state==1){
                   System.out.println("请输入借出日期：(yyyy-MM-dd):");
                   Scanner scanner2 = new Scanner(System.in);
                   String string = scanner2.next();
                   dvd.date = string;
                   dvd.state = 0;
                   dvd.count++;
               }else {
                   System.out.println("您要借的DVD已被借出！");
               }
           }
       }

       if(b == false){
           System.out.println("您输入的DVD不存在");
       }
       returnCom();
   }

//归还
   public void returnDVD(){
       System.out.println("******欢迎进入归还页面*****");
       System.out.print("请输入DVD名称：");
       Scanner scanner = new Scanner(System.in);
       String input = scanner.next();

       for(int i = 0; i < list.size(); i++){
           Dvd dvd = list.get(i);
           if(dvd.name.equals(input)){
               if(dvd.state == 0){
                   dvd.state = 1;
                   System.out.print("请输入归还的日期(yyyy-MM-dd)： ");
                   Scanner scanner2 = new Scanner(System.in);
                   String string = scanner2.next();
                   long money = money(string,dvd);
                   System.out.println("归还《"+input+"》成功");
                   System.out.println("需要付租金（￥）："+money);
               }else {
                   System.out.println("这DVD不是我们这里的吧，我们的DVD没有被借出！");
               }
           }
       }
       returnCom();
   }

// 算钱
   public long money(String string, Dvd dvd){
       long change = 0;
       SimpleDateFormat sd=new SimpleDateFormat("yyyy-MM-dd"); // 字符串转为Date做计算
       try{
           Date d1 = sd.parse(dvd.date); //该时间是以毫秒为单位，计算时记得转换
           Date d2 = sd.parse(string);
           change = (d2.getTime()-d1.getTime())/(24*60*60*1000); //转换得到天
       } catch(ParseException e){
           e.printStackTrace();
       }
       dvd.date = " ";
       return change;
   }

// 排行榜
   public void Top(){
       System.out.println("------TOP------");
       System.out.println("次数名称");

       Iterator<Dvd> it = list.iterator();
       TreeSet<Dvd> tSet = new TreeSet<>(new DVDCompar()); //传个比较器比较
       while(it.hasNext()){
           tSet.add(it.next());
       }
       it = tSet.iterator();
       while(it.hasNext()){
           Dvd dvd = it.next();
           System.out.println(dvd.count+" "+dvd.name);
       }

       returnCom();
   }

// 输入0返回菜单
   public void returnCom(){
       while(true){
           System.out.print("请输入0返回： ");
           Scanner scanner2 = new Scanner(System.in);
           int inputNum = scanner2.nextInt();

           if(inputNum == 0){
               System.out.println();
               returnMenu();
               break;
           } else {
               System.out.println("指令错误，请重新输入！");
           }
       }
   }

}
public class Demo {
   public static void main(String[] args) {
       // TODO Auto-generated method stub
       DvdMgr dvdMgr = new DvdMgr();
       dvdMgr.initial();
       dvdMgr.returnMenu();
   }
}