一个简陋的java图书管理系统

import java.util.Scanner;
public class Menu {
 int Min = 1;
 int Max = 3;
 public void getMenu(){
 System.out.println("1、显示/2、输入/3、查找");
 }
 public void getFindMenu(){
 System.out.println("1、编号/2、书名/3、作者");
 }
 public int setMenu(){
 System.out.println("输入序号:");
 Scanner reader = new Scanner(System.in);
 int num = reader.nextInt();
 if(num >= Min || num <= Max)
 return num;
 else
 return -1;
 }
}

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.util.Scanner;
import java.io.IOException;

public class Book {
 public void find(){
 Menu menu = new Menu();
 menu.getFindMenu();
 Scanner reader = new Scanner(System.in);
 int num = menu.setMenu();
 switch(num){
 case 1:
 System.out.println("请输入编号");
 Find(reader.next(), 0);
 break;
 case 2:
 System.out.println("请输入书名");
 Find(reader.next(), 1);
 break;
 case 3:
 System.out.println("请输入作者");
 Find(reader.next(), 2);
 break;
 }
 }
 public void Find(String s,int n){
 try {
 Scanner in = new Scanner(new File("res/Book.txt"));
 while (in.hasNextLine()) {
 String str = in.nextLine();
 String[] book = str.trim().split("#");
 if(book[n].compareTo(s) == 0)
  System.out.println(book[0] +" "+ book[1] +" "+ book[2]);
 }
 } catch (FileNotFoundException e) {
 e.printStackTrace();
 }
 }
 public String findNum(String s,int n){
 try {
 Scanner in = new Scanner(new File("res/Book.txt"));
 while (in.hasNextLine()) {
 String str = in.nextLine();
 String[] book = str.trim().split("#");
 if(book[n].compareTo(s) == 0)
  return book[n];
 }
 } catch (FileNotFoundException e) {
 e.printStackTrace();
 }
 return "没有找到";
 }
 public String message(){
 Scanner reader = new Scanner(System.in);
 String str = "";
 String s = "";
 System.out.println("请输入编号");
 str = reader.next();
 if(findNum(str,0).compareTo("没有找到") != 0){
 System.out.println("此编号存在输入错误");
 return "@@!!";
 }
 s += str + "#";
 System.out.println("请输入书名");
 str = reader.next();
 s += str + "#";
 System.out.println("请输入作者");
 str = reader.next();
 s += str + "#\n";
 return s;
 }
 public void setBook() {
 FileOutputStream fop = null;
 File file;
 String content = message();
 if(content.compareTo("@@!!") == 0)
 return ; 
 try {
 file = new File("res/Book.txt");
 fop = new FileOutputStream(file,true);
 byte[] contentInBytes = content.getBytes();
 fop.write(contentInBytes);
 fop.flush();
 fop.close();
 System.out.println("Done");
 } catch (IOException e) {
 e.printStackTrace();
 } finally {
 try {
 if (fop != null) {
  fop.close();
 }
 } catch (IOException e) {
 e.printStackTrace();
 }
 }
 }

 public void getBook() {
 try {
 Scanner in = new Scanner(new File("res/Book.txt"));
 while (in.hasNextLine()) {
 String str = in.nextLine();
 splitt(str);
 }
 } catch (FileNotFoundException e) {
 e.printStackTrace();
 }
 }

 public static String[] splitt(String str) {
 String[] book = str.trim().split("#");
 for (int i = 0; i < book.length; i++) {
 System.out.println(book[i]);
 }
 System.out.println("\n*********************");
 return book;
 }
}

public class ManageBook {
 public static void main(String[] agse){
 Menu menu = new Menu();
 Book book = new Book();
 while(true){
 menu.getMenu();
 int num = menu.setMenu();
 switch(num){
 case 1:
  book.getBook();
  break;
 case 2:
  book.setBook();
  break;
 case 3:
  book.find();
  break;
 case -1:
  System.out.println("输入有误");
  break;
 }
 }
 }

}