自己一直在自學Java基礎，期望向JavaWeb方向發展。自學了好長時間，每次基本上都不會怎麼記錄，昨天看了GitChat的推送，覺著應當把自己每天的學習記錄下來，這樣可以做到監督的作用。
今天這個是一個Java小練習，一個圖書借閱系統，需要實現的功能有：

• 判斷使用者是否需要進行借書
• 在使用者選擇借書時，展示出圖書列表
• 圖書列表包含 圖書序號、圖書名稱、借閱價格、作者
• 使用者選擇借書數量、並選擇對應圖書、借閱天數
• 計算出使用者需支付金額

Book.java

package com.imooc;

/**
 * 圖書類 包含圖書序號 名稱 價格
 * */

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("~~~~~~~歡迎使用圖書借閱系統~~~~~~~~ ");
        System.out.println("您是否要借書：1.是 >> 點選其他鍵退出");
        BorrowBooks test = new BorrowBooks();
        while (test.test1()) {
            System.out.println(">>>您可選擇圖書及其價目表：");
            System.out.println("-------------------------------------------");
            Book[] books = { new Book(0, "紅樓夢", 12, "曹雪芹"),
                    new Book(1, "西遊記", 12, "吳承恩"),
                    new Book(2, "漢鄉", 12, "孑與2"),
                    new Book(3, "大魏宮廷", 12, "賤宗首席"),
                    new Book(4, "三國演義", 12, "羅貫中"),
                    new Book(5, "水滸傳", 12, "施耐庵") };
            System.out.println("序號" + "  " + "\t" + "書名" + "     " + "\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("-->請輸入你要借書的數量：");
            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(">>請輸入第" + (i + 1) + "本書的序號：");
                    int num = zScanner.nextInt();
                    try {
                        bookList.add(books[num]);
                        System.out.println("----成功新增："
                                + 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("您輸入的圖書序號不正確");
                        i = i - 1;
                        BookNum = BookNum;
                    }

                }
                System.out.println("->請輸入借閱的天數：");
                Scanner g = new Scanner(System.in);
                int bookDay = g.nextInt();
                bookPrice = bookPrice * bookDay;
                System.out.println("------------借閱選書完成------------" + "\n"
                        + "下面開始統計資料..........");
                System.out.print("您借閱的圖書" + 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("->請輸入付款金額：");
                System.out.println("------------");
                Scanner x = new Scanner(System.in);
                 int priceSpread = bookPrice - x.nextInt();//定義差價
                 while (bookPrice != x.nextInt())

                 System.out.println("------------" + "\n" + "輸入錯誤，請重新輸入金額！");


                /*
                 while (bookPrice != x.nextInt())
                 {
                 if (bookPrice > x.nextInt()) {
             int priceSpread = bookPrice - x.nextInt();//定義差價
                 System.out.println("------------" + "\n" + "您已付款"
             + x.nextInt() + "元，還需支付" + priceSpread + "元");
                 }

             if (bookPrice <x.nextInt()) {
                 int priceSpread = x.nextInt()-bookPrice ;//定義差價
             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("------------感謝您的使用--------------");
                System.out.println("………………繼續借書請按1，退出請按其他鍵………………");
            } else {
                System.out.println("您輸入的借書數量為“0”，自動為您退出系統");
                System.exit(0);
            }

        }

    }

    private static Object bookPrice(int nextInt) {
        // TODO Auto-generated method stub
        return null;
    }

    // 捕獲輸入引數不正確異常
    public boolean test1() {
        try {
            Scanner z = new Scanner(System.in);
            if (z.nextInt() == 1) {
                return true;
            } else {
                return false;
            }
        } catch (Exception e1) {
            return false;
        }
    }
}

執行效果圖

存在問題

在BorrowBooks.java這個Class中，下面這段程式碼本想實現判斷使用者輸入的金額是否和應付金額一致，不一致時給出不同的回覆，但是自己試了好多種方法，都沒有實現，還是自己懂得太少：

     while (bookPrice != x.nextInt())
                 {
                 if (bookPrice > x.nextInt()) {
                 int priceSpread = bookPrice - x.nextInt();//定義差價
                 System.out.println("------------" + "\n" + "您已付款"
                 + x.nextInt() + "元，還需支付" + priceSpread + "元");
                 }

                 if (bookPrice <x.nextInt()) {
                 int priceSpread = x.nextInt()-bookPrice ;//定義差價
             System.out.println("------------" + "\n" + "您已付款"
             + x.nextInt() + "元，找您" + priceSpread + "元");
                 }
                 }