修改项目目录

src/Example22.java

@@ -1,2 +0,0 @@
-package PACKAGE_NAME;public class Example22 {
-}

src/Example23.java

@@ -1,2 +0,0 @@
-package PACKAGE_NAME;public class Example23 {
-}

src/GetMax.java

@@ -1,2 +0,0 @@
-package PACKAGE_NAME;public class GetMax {
-}

src/chapter2/ClassScoreAnalyzer.java

@@ -1,3 +1,5 @@
+package chapter2;
+
 public class ClassScoreAnalyzer {
     public static void main(String[] args) {
         // 1. 创建并初始化数组

src/chapter2/Department.java

@@ -1,3 +1,5 @@
+package chapter2;
+
 import java.util.Scanner;
 
 public class Department {

src/chapter2/Example07.java

@@ -1,3 +1,5 @@
+package chapter2;
+
 public class Example07 {
     public static void main(String[] args) {
         int x = 5;

src/chapter2/Example08.java

@@ -1,3 +1,5 @@
+package chapter2;
+
 public class Example08 {
     public static void main(String[] args) {
         int num = 20;

src/chapter2/Example09.java

@@ -1,3 +1,5 @@
+package chapter2;
+
 public class Example09 {
     public static void main(String[] args) {
         int grade = 75;

src/chapter2/Example10.java

@@ -1,3 +1,5 @@
+package chapter2;
+
 public class Example10 {
     public static void main(String[] args) {
         int x = 0;

src/chapter2/Example11.java

@@ -1,3 +1,5 @@
+package chapter2;
+
 public class Example11 {
     public static void main(String[] args) {
         int week = 1;

src/chapter2/Example12.java

@@ -1,3 +1,5 @@
+package chapter2;
+
 public class Example12 {
     public static void main(String[] args) {
         int x = 5;  // 定义变量x，初始值为1

src/chapter2/Example13.java

@@ -1,3 +1,5 @@
+package chapter2;
+
 public class Example13 {
     public static void main(String[] args) {
         int x = 5;

src/chapter2/Example14.java

@@ -1,3 +1,5 @@
+package chapter2;
+
 public class Example14 {
     public static void main(String[] args) {
         int sum = 0;

src/chapter2/Example16.java

@@ -1,10 +1,12 @@
+package chapter2;
+
 public class Example16 {
     public static void main(String[] args) {
         int x = 1;
         while (x <= 4) {
             System.out.println("x = " + x);
             if (x == 3) {
-                break;
+                continue;
             }
             x ++;
         }

src/chapter2/Example17.java

@@ -1,3 +1,5 @@
+package chapter2;
+
 public class Example17 {
     public static void main(String[] args) {
         int x = 1;

src/chapter2/Example19.java

@@ -1,6 +1,8 @@
+package chapter2;
+
 public class Example19 {
     public static void main(String[] args) {
-        printRectangle(3, 40);
+        printRectangle(3, 5);
     }
 
     // 下面定义了一个打印矩形的方法，接收两个参数，其中height为高，width为宽
@@ -8,10 +10,8 @@ public class Example19 {
         // 下面是使用嵌套for循环实现*打印矩形
         for (int i = 0; i < height; i++) {
             for (int j = 0; j < width; j++) {
-                System.out.print("*");
+
             }
-//            System.out.print("\n");
-            System.out.println();
         }
 
     }

src/chapter2/Example20.java

@@ -1,3 +1,5 @@
+package chapter2;
+
 public class Example20 {
     public static void main(String[] args) {
         int area = getArea(3, 5);

src/chapter2/Example21.java

@@ -1,3 +1,5 @@
+package chapter2;
+
 public class Example21 {
     public static void main(String[] args) {
         // 下面针对求和方法的调用

src/chapter2/Example22.java

@@ -0,0 +1,15 @@
+package chapter2;
+
+public class Example22 {
+    public static void main(String[] args) {
+        int[] arr;              // 声明变量
+        arr = new int[3];       // 创建数据对象
+
+        System.out.println("arr[0] = " + arr[0]);       // 访问数组中的第一个元素
+        System.out.println("arr[1] = " + arr[1]);       // 访问数组中的第二个元素
+        System.out.println("arr[2] = " + arr[2]);       // 访问数组中的第三个元素
+
+        System.out.println("数组的长度是：" + arr.length); // 打印数组的长度
+
+    }
+}

src/chapter2/Example23.java

@@ -0,0 +1,14 @@
+package chapter2;
+
+public class Example23 {
+    public static void main(String[] args) {
+        int[] arr = new int[4];     // 定义可以存储4个元素的整数类型数组
+        arr[0] = 1;                 // 为第1个元素赋值1
+        arr[1] = 1;                 // 为第2个元素赋值2
+        //依次打印数组中每个元素的值
+        System.out.println("arr[0]: " + arr[0]);
+        System.out.println("arr[1]: " + arr[1]);
+        System.out.println("arr[2]: " + arr[2]);
+        System.out.println("arr[3]: " + arr[3]);
+    }
+}

src/chapter2/GetMax.java

@@ -0,0 +1,7 @@
+package chapter2;
+
+public class GetMax {
+    public static void main(String[] args) {
+
+    }
+}

src/chapter2/SuperMarket.java

@@ -1,3 +1,5 @@
+package chapter2;
+
 import java.util.Scanner;
 
 public class SuperMarket {
@@ -29,26 +31,23 @@ public class SuperMarket {
                     int cupnumber = sc1.nextInt();
                     double cupnum = cupnumber * cup;
                     System.out.println("你购买了水杯" + cupnumber + "个，需要花费" + cupnum + "元");
-                    System.out.println("需要继续购买请输入Y，否则输入N");
-                    continueShopping = sc1.next();
                     break;
                 case 2:
                     System.out.println("请输入你需要购买苹果的数量:");
                     int applenumber = sc1.nextInt();
                     double applenum = applenumber * apple;
                     System.out.println("你购买了苹果" + applenumber + "斤，需要花费" + applenum + "元");
-                    System.out.println("需要继续购买请输入Y，否则输入N");
-                    continueShopping = sc1.next();
                     break;
                 case 3:
                     System.out.println("请输入你需要购买香蕉的数量:");
                     int banananumber = sc1.nextInt();
                     double banananum = banananumber * banana;
                     System.out.println("你购买了香蕉" + banananumber + "斤，需要花费" + banananum + "元");
-                    System.out.println("需要继续购买请输入Y，否则输入N");
-                    continueShopping = sc1.next();
                     break;
             }
+
+            System.out.println("需要继续购买请输入Y，否则输入N");
+            continueShopping = sc1.next();
         }
 
         System.out.println("期待您的下次光临！");

src/chapter2/User.java

@@ -0,0 +1,122 @@
+package chapter2;
+
+import java.util.Scanner;
+
+public class User {
+    // 存储用户名和密码
+    // 两个数组前加上static属性，这样做是为了让本类都可以使用到这两个数组
+    static String[] usernames = new String[10];
+    static String[] passwords = new String[10];
+
+    static int count = 1;
+
+    public static void main(String[] args) {
+        // 假设系统中已经有一个用户
+        usernames[0] = "java";
+        passwords[0] = "123456";
+
+        while (true) {
+            print();
+            Scanner input = new Scanner(System.in);
+            System.out.println("请选择功能：");
+            int option = input.nextInt();
+            switch (option) {
+                case 0:
+                    System.exit(0);
+                case 1:
+                    login();
+                    break;
+                case 2:
+                    register();
+                    break;
+                case 3:
+                    show();
+                    break;
+                default:
+                    System.out.println("输入错误！");
+                    break;
+            }
+        }
+    }
+
+    /*
+     * 登录功能，键盘输入用户名与密码
+     * 使用for循环加if判断验证输入的用户名与密码是否正确
+     */
+    public static void login() {
+        Scanner input = new Scanner(System.in);
+
+        System.out.println("请输入用户名：");
+        String username = input.next();
+
+        System.out.println("请输入密码：");
+        String password = input.next();
+
+        for (int i = 0; i < count; i++) {
+            if (username.equals(usernames[i]) && password.equals(passwords[i])) {
+                System.out.println("登录成功！");
+                return;
+            }
+        }
+
+        System.out.println("登录失败，请重新输入");
+    }
+
+    /*
+     * 注册功能
+     * 定义一个boolean变量，使用for循序判断用户是否存在
+     * 如果用户不存在，在数组中插入注册的账号密码时
+     * 可能会有数组长度不够的情况，所以需要使用到
+     * 增加数组的长度，这里调用增加数组长度的方法add()。
+     */
+    public static void register() {
+        Scanner input = new Scanner(System.in);
+
+        System.out.println("请输入用户名：");
+        String username = input.next();
+
+        System.out.println("请输入密码：");
+        String password = input.next();
+
+        boolean flag = true;
+        for (int i = 0; i < count; i++) {
+            if (username.equals(usernames[i])) {
+                System.out.println("用户名已存在");
+                flag = false;
+            }
+        }
+
+        if (flag) {
+            if (count < usernames.length) {
+                count++;
+                usernames[count - 1] = username;
+                passwords[count - 1] = password;
+                System.out.println("注册成功！");
+            } else {
+                System.out.println("数组空间不足！");
+            }
+
+        }
+    }
+
+    /*
+     * 查看功能
+     */
+    public static void show() {
+        for (int i = 0; i < count; i++) {
+            System.out.println("用户名：" + usernames[i] + "，密码：" + passwords[i]);
+        }
+    }
+
+    /*
+     * 打印功能菜单
+     */
+    public static void print() {
+        System.out.println("-----------------用户管理系统-------------------");
+        System.out.println("1.登录功能");
+        System.out.println("2.注册功能");
+        System.out.println("3.查看");
+        System.out.println("0.退出");
+        System.out.println("-----------------用户管理系统-------------------");
+    }
+}

src/chapter3/Example01.java

@@ -0,0 +1,37 @@
+package chapter3;
+
+class Student {
+    String name;
+    int age;
+    String sex;
+
+    void read() {
+        System.out.println("大家好，我是" + name + "，我在看书！");
+    }
+
+    void introduce() {
+        System.out.println("大家好，我叫" + name + "，我今年" + age + "岁了，我是" + sex + "孩");
+    }
+}
+
+public class Example01 {
+    public static void main(String[] args) {
+        Student s1 = new Student();
+        Student s2 = new Student();
+
+        s1.name = "小明";
+        s1.sex = "男";
+        s1.age = 20;
+
+
+        s2.name = "小红";
+        s2.sex = "女";
+        s2.age = 19;
+
+        s1.read();
+        s2.read();
+
+        s1.introduce();
+        s2.introduce();
+    }
+}

src/chapter3/Example05.java

@@ -0,0 +1,59 @@
+package chapter3;
+
+class Book {
+    int id;       // 编号
+    String name;  // 书名
+
+//    public Book() {
+//        this.id = 0;
+//        this.name = "未命名";
+//        System.out.println("初始化：无参构造被调用！");
+//    }
+
+    // 打印信息
+    public void print() {
+        System.out.println("print函数 - ID：" + this.id + "，书名：" + this.name);
+    }
+
+    // 获取书号
+    public int getId() {
+        return id;
+    }
+
+    // 设置书号
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    // 获取书名
+    public String getName() {
+        return name;
+    }
+
+    // 设置书名
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public static void main(String[] args) {
+        Book[] books = new Book[10];
+
+        // 使用 setter 初始化
+        books[0] = new Book();
+        books[0].print();
+        System.out.println("初始化：手动");
+        books[0].setId(1);
+        books[0].setName("Java教程");
+        books[0].print();
+
+        System.out.println("============");
+
+        // 直接访问属性进行初始化（注意访问控制）
+        books[1] = new Book();
+        books[1].print();
+        System.out.println("初始化：手动");
+        books[1].id = 2;
+        books[1].name = "JSP教程";
+        books[1].print();
+    }
+}

src/chapter3/demo31/Book.java

@@ -0,0 +1,36 @@
+package chapter3.demo31;
+
+public class Book {
+    private final int id;       // 编号
+    private final String name;  // 书名
+    private final double price; // 价格
+    private final int storage;  // 库存
+
+    // 有参构造
+    public Book(int id, String name, double price, int storage) {
+        this.id = id;
+        this.name = name;
+        this.price = price;
+        this.storage = storage;
+    }
+
+    // 获取书号
+    public int getId() {
+        return id;
+    }
+
+    // 获取书名
+    public String getName() {
+        return name;
+    }
+
+    // 获取价格
+    public double getPrice() {
+        return price;
+    }
+
+    // 获取库存
+    public int getStorage() {
+        return storage;
+    }
+}

src/chapter3/demo31/Order.java

@@ -0,0 +1,43 @@
+package chapter3.demo31;
+
+public class Order {
+    private final String orderId;
+    private final OrderItem[] items;
+    private double total;
+
+    // 有参构造
+    public Order(String orderId) {
+        this.orderId = orderId;
+        this.items = new OrderItem[3];
+    }
+
+    // 获取订单号
+    public String getOrderId() {
+        return orderId;
+    }
+
+    // 获取订单列表
+    public OrderItem[] getItems() {
+        return items;
+    }
+
+    // 获取订单总额
+    public double getTotal() {
+        calTotal();
+        return total;
+    }
+
+    // 指定一个订单项
+    public void setItem(OrderItem item, int i) {
+        this.items[i] = item;
+    }
+
+    // 计算订单总额
+    public void calTotal() {
+        double total = 0;
+        for (OrderItem item : items) {
+            total += item.getNum() * item.getBook().getPrice();
+        }
+        this.total = total;
+    }
+}

src/chapter3/demo31/OrderItem.java

@@ -0,0 +1,22 @@
+package chapter3.demo31;
+
+public class OrderItem {
+    private final Book book;
+    private final int num;
+
+    // 有参构造方法
+    public OrderItem(Book book, int num) {
+        this.book = book;
+        this.num = num;
+    }
+
+    // 获取图书对象
+    public Book getBook() {
+        return book;
+    }
+
+    // 获取订购图书数量
+    public int getNum() {
+        return num;
+    }
+}

src/chapter3/demo31/PayBooks.java

@@ -0,0 +1,64 @@
+package chapter3.demo31;
+
+import java.util.Scanner;
+
+public class PayBooks {
+    public static void main(String[] args) {
+        Book[] books = new Book[3];
+        // 模拟从数据库中读取图书信息并输出
+        outBooks(books);
+        // 顾客购买图书
+        Order order = purchase(books);
+        // 输出订单信息
+        outOrder(order);
+    }
+
+    // 顾客购买图书
+    public static Order purchase(Book[] books) {
+        Order order = new Order("00001");
+        OrderItem item = null;
+        Scanner in = new Scanner(System.in);
+
+        for (int i = 0; i < 3; i++) {
+            System.out.println("请输入图书编号选择图书：");
+            int cno = in.nextInt();
+            System.out.println("请输入购买图书数量：");
+            int pnum = in.nextInt();
+            item = new OrderItem(books[cno - 1], pnum);
+            order.setItem(item, i);
+            System.out.println("请继续购买图书。");
+        }
+        in.close();
+        return order;
+    }
+
+    // 输出订单信息
+    public static void outOrder(Order order) {
+        System.out.println("\n===================图书订单===================");
+        System.out.println("图书订单号：" + order.getOrderId());
+        System.out.println("图书名称\t购买数量\t图书单价");
+        System.out.println("--------------------------------------");
+        OrderItem[] items = order.getItems();
+        for (OrderItem item : items) {
+            System.out.println(
+                    item.getBook().getName() + "\t" + item.getNum() + "\t" + item.getBook().getPrice());
+        }
+        System.out.println("---------------------------------------");
+        System.out.println("订单总额：\t\t" + order.getTotal());
+    }
+
+    // 模拟从数据库中读取图书信息并输出
+    public static void outBooks(Book[] books) {
+        books[0] = new Book(1, "Java教程", 30.6, 30);
+        books[1] = new Book(2, "JSP教程", 42.1, 40);
+        books[2] = new Book(3, "SSH架构", 47.3, 15);
+        System.out.println("===================图书列表===================");
+        System.out.println("图书编号\t图书名称\t\t图书单价\t库存数量");
+        System.out.println("---------------------------------------");
+        for (int i = 0; i < books.length; i++) {
+            System.out.println(
+                    i + 1 + "\t" + books[i].getName() + "\t" + books[i].getPrice() + "\t" + books[i].getStorage());
+        }
+        System.out.println("---------------------------------------");
+    }
+}