运用ArrayList编写简单的图书管理系统

public class SystemEntry {

    public static void main(String[] args) {
        BookOperator operator = new BookOperator();
        Scanner sc = new Scanner(System.in);
        while (true) {
            System.out.println("--------欢迎来到图书管理系统--------");
            System.out.println("1 添加图书");
            System.out.println("2 删除图书");
            System.out.println("3 修改图书");
            System.out.println("4 查看图书");
            System.out.println("5 退出");
            System.out.println("请输入您的选择:");
            String choice = sc.next();
            switch (choice) {
                case "1":
                    operator.addBook();
                    break;
                case "2":
                    operator.delBook();
                    break;
                case "3":
                    operator.updeteBook();
                    break;
                case "4":
                    operator.findAllBooks();
                    break;
                case "5":
                    System.out.println("欢迎下次再来");
                    System.exit(0);//退出
                default:
                    System.out.println("输入有误!!");
                    break;
            }
        }
    }
}

public class Book {
   private String id;
   private String name;
   private double price;
   private String description;

    public Book() {
    }

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

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public double getPrice() {
        return price;
    }

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

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    @Override
    public String toString() {
        return "Book{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", price=" + price +
                ", description='" + description + '\'' +
                '}';
    }
}

public class BookOperator {

    private ArrayList<Book> books = new ArrayList<>();
    private Scanner sc = new Scanner(System.in);

    public void addBook() {
        String id = null;
        while (true) {
            System.out.println("请输入图书id");
            id = sc.next();
            int index = findIndexById(id);
            if (index < 0) {
                break;
            } else {
                System.out.println("输入的图书id重复,请重新输入!!");
            }
        }

        System.out.println("请输入书名");
        String name = sc.next();
        System.out.println("请输入价格");
        double price = sc.nextDouble();
        System.out.println("请输入图书描述");
        String description = sc.next();
        Book book = new Book(id, name, price, description);
        books.add(book);
        System.out.println("添加成功!!");
    }

    public void delBook() {
        System.out.println("请输入图书id");
        String id = sc.next();
        int index = findIndexById(id);
        if (index < 0) {
            System.out.println("删除的图书不存在,请重新输入");
        } else {
            books.remove(index);
            System.out.println("删除成功!!");
        }
    }


    public void updeteBook() {
        System.out.println("请输入图书id");
        String id = sc.next();
        int index = findIndexById(id);
        if (index < 0) {
            System.out.println("更新的图书不存在,请重新输入");
        } else {
            System.out.println("请输入书名");
            String name = sc.next();
            System.out.println("请输入价格");
            double price = sc.nextDouble();
            System.out.println("请输入图书描述");
            String description = sc.next();
            Book book = new Book(id, name, price, description);
            books.set(index, book);
            System.out.println("更新成功!!");
        }
    }

    private int findIndexById(String id) {
        for (int i = 0; i < books.size(); i++) {
            if (id.equals(books.get(i).getId())) {
                return i;
            }
        }
        return -1;
    }


    public void findAllBooks() {
        if (books == null || books.size() == 0) {
            System.out.println("图书为空,请先添加");
            return;
        }
        System.out.println("图书id\t书名\t价格\t描述");
        for (int i = 0; i < books.size(); i++) {
            Book book = books.get(i);
            System.out.println(book.getId() + "\t" + book.getName() + "\t" +
                    book.getPrice() + "元\t" + book.getDescription());
        }
    }
}