java第三季 图书管理系统 学习异常

import java.util.Scanner;

public class Book {

    /**
     * @param args
     */

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input=new Scanner(System.in);
        System.out.println("欢迎来到");
    //定义图书数组
        final int [] booknum ={1,2,3,4,5};
        final String [] bookname={"c++","java","计算机基础","汇编语言","算法"};
    //展示编号和图书
        for(int i=0;i<5;i++)
        System.out.println(booknum[i]+"\t"+bookname[i]+"\t");
    //选择方式
        System.out.println("请输入查询方式的编号！1.按照编号查询 2.按照书名查询");
        try{
        String number=input.next();
    //进行选择
        switch(number){
        case "1":       //1编号查询
            System.out.println("请输入编号");
            nums(bookname);
            break;
        case "2":       //2书名查询
            System.out.println("请输入书名");
            names(bookname);
            break;
        default:        //输入错误
            System.out.println("输入错误,请输入正确数字");
        }
        }catch(Exception aaa){
            System.out.println(aaa.getMessage());

        }

}

    //编号查询方法
    public static void nums(String [] bookname){
        Scanner in=new Scanner(System.in);
        try{
            int a=in.nextInt();
            System.out.println("给你"+bookname[a-1]);
        }catch(Exception a){
            System.out.println("无此书");
        }
    }

    //名字查询方法
    public static void names(String [] bookname)
            throws Exception{
        Scanner in=new Scanner(System.in);
            String b=in.nextLine();
            for(int i=0;i<bookname.length;i++){
                if (b.equals(bookname[i]))
                System.out.println("给你"+bookname[i]);
                                return;
            }throw new Exception("暂无此书");
    }   
    }