Java practical sharing—the operating effects and existing problems of the book lending system

I have been learning the basics of Java by myself and hope to develop in the direction of JavaWeb. I have been studying by myself for a long time, but I basically don’t know how to record it every time. Yesterday I saw the GitChat push, and I felt that I should record my daily learning, so that it can serve as a supervision.

Today this is a small Java exercise, a book lending system. The functions that need to be implemented are:

• Determine whether the user needs to borrow a book

• When the user chooses to borrow a book, the book list is displayed

• The book list includes the book serial number, book name, borrowing price, and author

• The user selects the number of books to borrow, and selects the corresponding book and the number of borrowing days

• Calculate the amount the user needs to pay

Book.java

package com.imooc;/**
 * 图书类 包含图书序号 名称 价格
 * */public class Book {
    private int id;    private String name;    private double price;    private String author;    public Book(int id, String name, double price, String author) {        // TODO Auto-generated constructor stub
        this.id = id;        this.setName(name);        this.price = price;        this.author = author;
    }    public void setId(int id) {        this.id = id;
    }    public int getId() {        return id;
    }    public void setPrice(double price) {        this.price = price;
    }    public double getPrice() {        return price;
    }    public void setAuthor(String author) {        this.author = author;
    }    public String getAuthor() {        return author;
    }    public void setName(String name) {        this.name = name;
    }    public String getName() {        return name;
    }

}

BorrowBooks.java

package com.imooc;

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;public class BorrowBooks {    /**
     * @param args
     */
    public static void main(String[] args) {        // TODO Auto-generated method stub
        System.out.println("~~~~~~~欢迎使用图书借阅系统~~~~~~~~ ");
        System.out.println("您是否要借书：1.是 >> 点击其他键退出");
        BorrowBooks test = new BorrowBooks();        while (test.test1()) {
            System.out.println(">>>您可选择图书及其价目表：");
            System.out.println("-------------------------------------------");
            Book[] books = { new Book(0, "红楼梦", 12, "曹雪芹"),                    new Book(1, "西游记", 12, "吴承恩"),                    new Book(2, "汉乡", 12, "孑与2"),                    new Book(3, "大魏宫廷", 12, "贱宗首席"),                    new Book(4, "三国演义", 12, "罗贯中"),                    new Book(5, "水浒传", 12, "施耐庵") };
            System.out.println("序号" + "  " + "\t" + "书名" + "     " + "\t"
                    + "租金" + "      " + "\t" + "作者");            for (Book book : books) {                if (book.getClass().equals(Book.class)) {
                    System.out.println(book.getId() + "\t" + "\t"
                            + book.getName() + "\t" + "\t" + book.getPrice()
                            + "/天" + "\t" + "\t" + book.getAuthor() + "/著");
                }
            }
            System.out.println("-------------------------------------------");
            System.out.println("-->请输入你要借书的数量：");
            Scanner zScanner = new Scanner(System.in);            int BookNum = zScanner.nextInt();            if (BookNum > 0) {
                List<Book> bookList = new ArrayList<Book>();                int add = 0;                int bookPrice = 0;                for (int i = 0; i < BookNum; i++) {
                    System.out.println(">>请输入第" + (i + 1) + "本书的序号：");                    int num = zScanner.nextInt();                    try {
                        bookList.add(books[num]);
                        System.out.println("----成功添加："
                                + bookList.get(add).getName());                        if (books[num].getClass().equals(Book.class)) {
                            bookPrice += ((Book) bookList.get(add)).getPrice();
                        }
                        add++;
                    } catch (Exception e) {                        // TODO: handle exception
                        System.out.println("您输入的图书序号不正确");
                        i = i - 1;
                        BookNum = BookNum;
                    }

                }
                System.out.println("->请输入借阅的天数：");
                Scanner g = new Scanner(System.in);                int bookDay = g.nextInt();
                bookPrice = bookPrice * bookDay;
                System.out.println("------------借阅选书完成------------" + "\n"
                        + "下面开始统计数据..........");
                System.out.print("您借阅的图书" + BookNum + "本：" + " ");                for (Book book : bookList) {
                    System.out.println(book.getName() + " " + "\n");
                }
                System.out.println();
                System.out.println("共租用：" + bookDay + " 天");
                System.out.println("需要付款：" + bookPrice + " 元");
                System.out.println("->请输入付款金额：");
                System.out.println("------------");
                Scanner x = new Scanner(System.in);                 int priceSpread = bookPrice - x.nextInt();//定义差价
                 while (bookPrice != x.nextInt())

                 System.out.println("------------" + "\n" + "输入错误，请重新输入金额！");                /*
                 while (bookPrice != x.nextInt())
                 {
                 if (bookPrice > x.nextInt()) {
             int priceSpread = bookPrice - x.nextInt();//定义差价
                 System.out.println("------------" + "\n" + "您已付款"
             + x.nextInt() + "元，还需支付" + priceSpread + "元");
                 }

             if (bookPrice <x.nextInt()) {
                 int priceSpread = x.nextInt()-bookPrice ;//定义差价
             System.out.println("------------" + "\n" + "您已付款"
             + x.nextInt() + "元，找您" + priceSpread + "元");
             }
*/
                System.out.println("------------");
                System.out.println("              交易成功！");
                System.out.println();
                System.out.println("------------感谢您的使用--------------");
                System.out.println("………………继续借书请按1，退出请按其他键………………");
            } else {
                System.out.println("您输入的借书数量为“0”，自动为您退出系统");
                System.exit(0);
            }

        }

    }    private static Object bookPrice(int nextInt) {        // TODO Auto-generated method stub
        return null;
    }    // 捕获输入参数不正确异常
    public boolean test1() {        try {
            Scanner z = new Scanner(System.in);            if (z.nextInt() == 1) {                return true;
            } else {                return false;
            }
        } catch (Exception e1) {            return false;
        }
    }
}

---

Running renderings

##There is a problem

In the BorrowBooks.java class, the following code is intended to determine whether the amount entered by the user is consistent with the amount payable, and give a different reply if it is inconsistent. However, I have tried many methods, but none of them have been implemented. I still know too little. :

     while (bookPrice != x.nextInt())
                 {                 if (bookPrice > x.nextInt()) {                 int priceSpread = bookPrice - x.nextInt();//定义差价
                 System.out.println("------------" + "\n" + "您已付款"
                 + x.nextInt() + "元，还需支付" + priceSpread + "元");
                 }                 if (bookPrice <x.nextInt()) {                 int priceSpread = x.nextInt()-bookPrice ;//定义差价
             System.out.println("------------" + "\n" + "您已付款"
             + x.nextInt() + "元，找您" + priceSpread + "元");
                 }
                 }

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