Java异常之图书管理系统

package com.tony;
/*
 * 图书租赁系统
 */
public class Book {
 public String bookName;
 public int bookId;
 public Book(String bookName, int bookId){
  this.bookName = bookName;
  this.bookId = bookId;
 } 
}

package com.tony;
/*
 * 自定义异常类
 */
public class MyException extends Exception{
 //有参构造方法
 public MyException(String message) {
  super(message);
 };
}

package com.tony;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;
/*
 * 主程序
 */
public class BorrowBook {

 Book book [] = {new Book("高等数学", 1), new Book("大学英语", 2), new Book("Android", 3), new Book("会计基础", 4)};
 public List<Book> listBooks;
 //无参构造方法
 public BorrowBook() {
  this.listBooks = new ArrayList<Book>();
 }
 public void addBook(){
  listBooks.addAll(Arrays.asList(book));
 } 
 public void systemOut() {
  System.out.println("*******欢迎使用借书系统*******");
  System.out.println("*-*-*-*图书一览表：*-*-*-*");
  System.out.println("  书名" + "\t\t" + "序号");
  for(Book book:listBooks) {
   System.out.println(book.bookName + "\t\t " +book.bookId);
  }
 }
 private Scanner scanner = new Scanner(System.in);
 public static void main(String[] args) {
  BorrowBook borrowBook = new BorrowBook();
  borrowBook.addBook();
  borrowBook.systemOut();

  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");
   switch (borrowBook.scanf()) {
   case 1://根据用户不同的输入内容执行
    try {
     System.out.println("书籍：" + borrowBook.findByName());
     break;
    } catch (Exception e) {
     System.out.println(e.getMessage());
     continue;
    }
   case 2:
    try {
     System.out.println("书籍：" + borrowBook.findById()); 
     break;
    } catch (Exception e) {
     System.out.println(e.getMessage());
     continue;
    }
    default:
     System.out.println("命令错误，请重试.");
     continue;
   }
   break;
  }
  borrowBook.scanner.close();
 }
 public String findByName() throws MyException{
  System.out.println("*****请输入书籍的名称-->");
  String name = scanner.next();
  for (Book books : book) {
   if (name.equals(books.bookName)) {
    return books.bookName + "\t序号：" +books.bookId;
   }
  }
  throw new MyException("名称错误，请重试.");
 }
 public String findById() throws MyException {
  System.out.println("*****请输入书籍的序号-->");
  int in = scanner.nextInt();
  for (int i = 0; i < book.length; i++) {
   if (in == (i + 1)) {
    return book[i].bookName + "\t序号：" + (i+1);
   }
  }
  throw new MyException("下标越界，请重试.");
 }
 public int scanf() {
  try {
   int in = scanner.nextInt();
   return in;
  } catch(Exception e) {
   scanner = new Scanner(System.in);
   return -1;
  }
 }
}