写一个图书管理系统java代码，要简单且有增加，删除，查询，修改四个功能；

好的，以下是一个简单的图书管理系统Java代码，包含增加、删除、查询和修改四个功能：

import java.util.ArrayList;
import java.util.Scanner;

public class BookManagementSystem {
    private static ArrayList<Book> bookList = new ArrayList<Book>();
    private static Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) {
        // 初始化图书列表
        bookList.add(new Book("001", "Java程序设计", "张三", "清华大学出版社", 59.9));
        bookList.add(new Book("002", "数据结构与算法", "李四", "人民邮电出版社", 49.9));
        bookList.add(new Book("003", "数据库系统原理", "王五", "机械工业出版社", 69.9));

        while (true) {
            System.out.println("请输入数字选择对应的功能：");
            System.out.println("1. 添加图书");
            System.out.println("2. 删除图书");
            System.out.println("3. 查询图书");
            System.out.println("4. 修改图书信息");
            System.out.println("5. 退出系统");
            int choice = scanner.nextInt();
            scanner.nextLine(); // 清空缓冲区

            switch (choice) {
                case 1:
                    addBook();
                    break;
                case 2:
                    deleteBook();
                    break;
                case 3:
                    searchBook();
                    break;
                case 4:
                    updateBook();
                    break;
                case 5:
                    System.out.println("感谢使用图书管理系统！");
                    System.exit(0);
                default:
                    System.out.println("请输入正确的数字！");
                    break;
            }
        }
    }

    // 添加图书
    private static void addBook() {
        System.out.println("请输入添加的图书信息：");
        System.out.print("编号：");
        String id = scanner.nextLine();
        System.out.print("书名：");
        String name = scanner.nextLine();
        System.out.print("作者：");
        String author = scanner.nextLine();
        System.out.print("出版社：");
        String publisher = scanner.nextLine();
        System.out.print("价格：");
        double price = scanner.nextDouble();
        scanner.nextLine(); // 清空缓冲区

        Book book = new Book(id, name, author, publisher, price);
        bookList.add(book);
        System.out.println("添加成功！");
    }

    // 删除图书
    private static void deleteBook() {
        System.out.println("请输入要删除图书的编号：");
        String id = scanner.nextLine();

        for (int i = 0; i < bookList.size(); i++) {
            Book book = bookList.get(i);
            if (book.getId().equals(id)) {
                bookList.remove(i);
                System.out.println("删除成功！");
                return;
            }
        }
        System.out.println("没有找到对应的图书！");
    }

    // 查询图书
    private static void searchBook() {
        System.out.println("请输入要查询图书的编号：");
        String id = scanner.nextLine();

        for (Book book : bookList) {
            if (book.getId().equals(id)) {
                System.out.println(book);
                return;
            }
        }
        System.out.println("没有找到对应的图书！");
    }

    // 修改图书信息
    private static void updateBook() {
        System.out.println("请输入要修改图书的编号：");
        String id = scanner.nextLine();

        for (Book book : bookList) {
            if (book.getId().equals(id)) {
                System.out.println("请输入修改后的图书信息：");
                System.out.print("书名（原书名：" + book.getName() + "）：");
                String name = scanner.nextLine();
                System.out.print("作者（原作者：" + book.getAuthor() + "）：");
                String author = scanner.nextLine();
                System.out.print("出版社（原出版社：" + book.getPublisher() + "）：");
                String publisher = scanner.nextLine();
                System.out.print("价格（原价格：" + book.getPrice() + "）：");
                double price = scanner.nextDouble();
                scanner.nextLine(); // 清空缓冲区

                book.setName(name);
                book.setAuthor(author);
                book.setPublisher(publisher);
                book.setPrice(price);
                System.out.println("修改成功！");
                return;
            }
        }
        System.out.println("没有找到对应的图书！");
    }
}

class Book {
    private String id;
    private String name;
    private String author;
    private String publisher;
    private double price;

    public Book(String id, String name, String author, String publisher, double price) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.publisher = publisher;
        this.price = price;
    }

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public String getPublisher() {
        return publisher;
    }

    public void setPublisher(String publisher) {
        this.publisher = publisher;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    @Override
    public String toString() {
        return "编号：" + id + "，书名：" + name + "，作者：" + author + "，出版社：" + publisher + "，价格：" + price;
    }
}

使用方法：
1. 将代码保存到名为 `BookManagementSystem.java` 的文件中
2. 在命令行中进入代码所在的目录，执行 `javac BookManagementSystem.java` 编译代码
3. 执行 `java BookManagementSystem` 运行程序，按照提示进行操作