利用异常处理编写模拟借书系统程序

import java.util.*;
class Index {
    static int  flag = 0;
    //定义一个字符串数组存放书籍
    String[] books = new String[]
    {"java编程思想","高等数学","Java疯狂讲义",
    "从你的全世界路过","幻城","大学英语","努力","加油","做自己"};
    //浏览方式选择方法
    public void showEnter() {
        System.out.println("请选择浏览图书的方式：");
        System.out.println("1:按照名称查找"+"\t"+"2:按照序号查找");
        Scanner sc = new Scanner(System.in);
        int choose = sc.nextInt();
        if (choose==1) {
            flag = 1;
            System.out.println("请输入名称");
            dispByName();

        }else if (choose==2) {
            flag = 1;
            System.out.println("请输入序号");

            dispByNum();
        }else {
            System.out.println("输入无效，请按照要求输入！");
            showEnter();
        }   
    }

    //主方法
    public static void main(String[] args) 
    {
        Index ix = new Index();
        while(flag==0) {
            ix.chooseStyle();
        }   
    }
    //判断选择方式的方法
    public void chooseStyle() {
        try {
                showEnter();    
            }
            catch (InputMismatchException e) {
                System.out.println("输入无效，请重新选择浏览方式：");
                chooseStyle();
            }
    }
    //定义一个按照序号显示图书的方法
    public void dispByNum() {       
        Scanner sc = new Scanner(System.in);        
        try{    
            int index = sc.nextInt();
            if (index<=0||index>books.length) {
                throw new Exception();
            }
            System.out.println(books[index-1]);
        }catch(Exception e) {
            System.out.println("请输入合适的序号1-"+books.length);
            dispByNum();
        }       
    }
    //定义一个按照名称显示图书的方法
    public void dispByName() {
        Scanner sc = new Scanner(System.in);
        String name = sc.nextLine();
        int flag = 0;
        int j = 0;
        try {
            for (int i=0;i<books.length ;i++ ) {
                if (books[i].equals(name)) {                
                    j = i;
                    System.out.println("你好，你查找的图书是第"+(j+1)+"个");
                    flag=1;
                }
            }
            if (flag==0) {
                throw new Exception();
            }
        }catch (Exception e) {
            System.out.println("输入的名字有误，重新输入：");        
            dispByName();
        }   
    }
}