Java入门第三季1-9 借书系统尝试

自己编写的尽量用到了，老师课程中所授的内容
欢迎大家交流，错误地方请指正
自定义异常类

package com.kangjia.book;

public class DigitalAcross extends Exception {
    public DigitalAcross() {
    }

    public DigitalAcross(String msg) {
        super(msg);
    }
}

主要类

package com.kangjia.book;

import java.util.InputMismatchException;
import java.util.Scanner;

public class Book {
    static String BookNameSql[] = { "高数", "数据结构" };
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int Choose = 0;
        while (true) {
            System.out.println("输入命令：1-按照名称查找图书；2-按照序号查找图书");
            Scanner scanner = new Scanner(System.in);
            try {
                Choose = scanner.nextInt();
                even(Choose);
            } catch (DigitalAcross e) {
                // TODO Auto-generated catch block
                System.out.println("您输入的数字不符合要求");
            } catch (InputMismatchException e) {
                System.out.println("请您输入数字");
            }
            if (Choose == 1) {
                NameQuery();
            } else if (Choose == 2) {
                NumberQuery();
            }

        }

    }
    // 自定义异常，用于判断用户输入的数字是否满足要求
    public static void even(int Choose) throws DigitalAcross {
        if (Choose > 3 || Choose < 0) {
            throw new DigitalAcross("");
        }
    }

    // 图书名称查询
    public static void NameQuery() {
        System.out.println("请输入图书名称");
        Scanner scanner = new Scanner(System.in);
        String BookName = scanner.next();
        if (Query(BookName)==1) {
            System.out.println("图书不存在");    
        }
    }
//图书名称查询辅助循环方法
    public static int Query(String BookName){
        for (String NameQuery : BookNameSql) {
            if (BookName.equals(NameQuery)) {
                System.out.println("Book:"+NameQuery);
                return 0;
            } 
        }
        return 1;

    }
    // 图书编号进行查询
    public static void NumberQuery() {
        System.out.println("请输入图书序号");
        Scanner scanner = new Scanner(System.in);
        int BookNumber = scanner.nextInt();
        try {
            if (BookNameSql[BookNumber] != null) {
                System.out.println("Book:"+BookNameSql[BookNumber]);
                System.exit(0);
            }
        } catch (Exception e) {
            System.out.println("图书不存在");
        }
    }

}