public String [] dvd = new String [50] ; //储存DVD信息
    public int[] Lendstate = new int [50] ;//借出状态，0为已借出,1为可借出
    public String[] data = new String [50];//定义日期
    Scanner sc = new Scanner (System.in);



    //借出DVD
    
    public void lentdvd (){
        String lentname="";
        boolean zhi = true;
        System.out.println("可以借出的DVD：");
        for (int w=0;w<dvd.length;w++){
            if (dvd[w]!=null){
            System.out.println(dvd[w]);
            }
        }
        System.out.println("请输入需要借出的DVD:");
        
        //for (int t=0;t<data.length;t++){
            lentname = sc.next();
            int random = (int)(Math.random()*49);
            System.out.println("请输入借出的日期(以-号分隔,参照:2012-06-01):");
            String riqi = sc.next();
            if (data[random]==null){
                data[random]=riqi;//////////////////无法将这个值放入数组，而且在下面无法获取
            }
        for (int r=0;r<dvd.length;r++){
            if (lentname.equalsIgnoreCase(dvd[r])&&Lendstate[r]==1){
                System.out.println("借出成功!");
                //Lendstate=1; //定义借出成功状态
                Lendstate[r]=0;
                zhi=true;
            }
            //}
        }
        if (zhi==false){
            System.out.println("借出失败");
            System.out.println();    
        }
        
        for (int q=0;q<data.length;q++){
            if (data[q]!=null){
                System.out.println(data[q]);
            }
        }
        
        }
        
    
    /////////////////////////////////////////////////////////归还DVD
    
    public void returndvd (){
        boolean zhi = true;
        System.out.println("请输入DVD名称：");
        String returnName = sc.next();
        
        for (int c=0;c<data.length;c++){
            if (data[c]!=null){
                System.out.println(data[c]);
            }
        }
        
        
        System.out.println("请输入归还的日期(以-号分隔,参照:2012-06-01):");
        String sReturn =  sc.next();//归还的日期
        String sBorrow="";
        for (int e=0;e<dvd.length;e++){
            if ((returnName.equalsIgnoreCase(dvd[e]))&&Lendstate[e]==0&&data[e]!=null){
                zhi=true;
                sBorrow=data[e];/////////////这一步有错，但按照逻辑来说是没错的
            }
        }
        if (zhi==true){
            
            final double MILLS_TO_DAY = 1000d * 60 * 60 * 24;

            // 可以加一些格式验证

            SimpleDateFormat formater = new SimpleDateFormat("yyyy-MM-dd");
            Date borrowDate = null;
            Date returnDate = null;
                try
                {
                    borrowDate = formater.parse(sBorrow);
                    returnDate = formater.parse(sReturn);
                }
            
            
            catch (ParseException e)
            {
                e.printStackTrace();
            }
            
        //else{
            
            
            //System.out.println("归还失败!");
            
            System.out.println("供需支付(元):"+(returnDate.getTime() - borrowDate.getTime())/ MILLS_TO_DAY);
            
        }
}

int random = (int)(Math.random()*49); //不知道这个随机的意义是什么
            System.out.println("请输入借出的日期(以-号分隔,参照:2012-06-01):");
            String riqi = sc.next();
            //if (data[random]==null){
            //    data[random]=riqi;//这里是随机保存，和DVD的位置不一致
            //}

          for (int r=0;r<dvd.length;r++){
            if (lentname.equalsIgnoreCase(dvd[r])&&Lendstate[r]==1){ 
                System.out.println("借出成功!");
                //Lendstate=1; //定义借出成功状态
                Lendstate[r]=1;
                data[r] = riqi; //在这里设置借书日期
                zhi=true;
            }
            //}
        }