1. 输入命令类型错误，抛出命令错误异常，并提示重新输入
2. 输入命令不存在，抛出命令错误异常，并提示重新输入
3. 输入书名不存在，抛出异常，并提示重新输入
4. 输入序号类型错误，抛出序号不正确异常，并提示重新输入
5. 输入序号越界，抛出序号越界异常，并提示重新输入

package com.xk;
import java.util.Scanner;

public class FindBook {
    Scanner input=new Scanner(System.in);
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String books[]= new String[]{"语文","数学","英语","Java","Android"};
        System.out.println("-----------欢迎使用我的借书系统-----------");
        FindBook fb=new FindBook();
        while(true) {
            System.out.println("请您输入命令:1.按名称查找书籍\t2.按序号查找书籍");
            switch(fb.scanf()) {
            case 1: 
                try {
                    System.out.println("book:"+fb.byName(books));
                    break;
                    }catch(Exception e){
                        System.out.println(e.getMessage());
                        continue;
                    }
            case 2:
                try {
                    System.out.println("book:"+fb.byId(books));
                    break;
                    }catch(Exception e){
                    System.out.println(e.getMessage());
                    continue;
                    }
            default : System.out.println("错误命令请按提示输入,请重新输入:");continue;
            }
            break;
        }
        fb.input.close();
    }

    public int scanf(){
        try{
            int in=input.nextInt();
            return in;
        }catch(Exception e){
            input=new Scanner(System.in);
            return -1;
        }
    }

    public String byName(String books[])throws Exception{
        System.out.println("请输入图书名称:");
        String name=input.next();
        for(int i=0;i<books.length;i++){
            if(name.equals(books[i])){
                return books[i];
            }
        }
        throw new Exception("图书不存在!");
    }

    public String byId(String books[])throws Exception{
        System.out.println("请输入图书序号:");
        FindBook fb=new FindBook();
        int flag=fb.scanf();
        if(flag==-1) {
            throw new Exception("输入序号不正确");
        }
        try {
            return books[flag];
        }catch(ArrayIndexOutOfBoundsException e){
            throw new ArrayIndexOutOfBoundsException("输入序号越界");
        }
    }
}