一个借书系统，主要是使用异常来对借书时的情况进行把控。
基本可以跑。写的还是有点乱。
不足的地方还是很多的，希望大家指教，代码如下：

package com.Library;
import java.util.*;
public class BookNewSystem {
    final Book[] books={new Book(1,"数据结构"),new Book(2,"高数"),new Book(3,"C语言")}; 
     static Scanner input = new Scanner(System.in);
    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        BookNewSystem BNS = new BookNewSystem();        
        while(true){
        System.out.println("输入命令：1-按照书名查找图书；2-按照序号查找图书");
        try{
        int input_number = inputNumber(); 
        switch(input_number){
        case 1:
            System.out.println("输入图书名称：");
            String bookname = input.next();
            String temp = BNS.FindBookByName(bookname);
//          BNS.FindBookByName(bookname);
            System.out.println("book："+bookname);
            break;
        case 2:
            BNS.FindBookByOrder();
//          System.out.println("输入图书序号：");
//          int booknumber = inputNumber();
            break;

        default:
            System.out.println("命令输入错误！请根据提示输入数字命令！");
            continue;
        }
        break;
        }

        catch(Exception me){
            System.out.println(me.getMessage());
            continue;
        }       
        }

    }

     int FindBookByOrder(){
         int j=0;
         while(true){
         System.out.println("输入图书序号：");
         int booknumber = inputNumber();
         if(booknumber==-1){
             System.out.println("命令输入错误！请根据提示输入数字命令！");
             continue;
         }
         else{
             if(booknumber>books.length){
                 System.out.println("图书不存在");

                 break;
             }
             else{
                 System.out.println("book:"+books[booknumber-1].BookName);
                 break;
             }
         }

      }
         return 0; 
     }

     String FindBookByName(String name) throws Exception {
        int i=0;
        for(;i<books.length;++i){
            if(name.equals(books[i].BookName))
                return name;
        }
        throw new Exception("图书真的不存在！"+name);
    }

    static int inputNumber(){
        int order;
        Scanner inp = new Scanner(System.in);
        try{
            order = inp.nextInt();
            return order;
        }
        catch(Exception e){
            return -1;
        }       
    }   
}