feat(w3): 添加w3文件夹及Car.java、TeatCar.java和实验报告PDF

w3/Car.java

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+// Car.java
+public class Car {
+    // 私有属性
+    private final String licensePlate;
+    private String brand;
+    private String model;
+    private double dailyRent;
+    private boolean isRented;
+
+    // 静态变量：统计车辆总数
+    private static int totalCars = 0;
+
+    // 全参构造方法
+    public Car(String licensePlate, String brand, String model, double dailyRent) {
+        this.licensePlate = licensePlate;
+        this.brand = brand;
+        this.model = model;
+        setDailyRent(dailyRent);
+        this.isRented = false;
+        totalCars++;
+    }
+
+    // 重载构造方法（日租金默认300）
+    public Car(String licensePlate, String brand, String model) {
+        this(licensePlate, brand, model, 300.0);
+    }
+
+    // Getter/Setter
+    public String getLicensePlate() {
+        return licensePlate;
+    }
+
+    public String getBrand() {
+        return brand;
+    }
+
+    public void setBrand(String brand) {
+        this.brand = brand;
+    }
+
+    public String getModel() {
+        return model;
+    }
+
+    public void setModel(String model) {
+        this.model = model;
+    }
+
+    public double getDailyRent() {
+        return dailyRent;
+    }
+
+    public void setDailyRent(double dailyRent) {
+        if (dailyRent > 0) {
+            this.dailyRent = dailyRent;
+        } else {
+            System.out.println("日租金必须大于0，设置失败！");
+        }
+    }
+
+    public boolean isRented() {
+        return isRented;
+    }
+
+    // 业务方法：租车
+    public void rentCar() {
+        if (isRented) {
+            System.out.println("车辆已租出，无法再次租用！");
+        } else {
+            isRented = true;
+            System.out.println("车辆已成功租出！");
+        }
+    }
+
+public class Car {
+    private final String licensePlate;
+    private String brand;
+    private String model;
+    private double dailyRent;
+    private boolean isRented;
+    private static int totalCars = 0;
+
+    // 全参构造方法
+    public Car(String licensePlate, String brand, String model, double dailyRent) {
+        this.licensePlate = licensePlate;
+        this.brand = brand;
+        this.model = model;
+        setDailyRent(dailyRent);
+        this.isRented = false;
+        totalCars++;
+    }
+
+    // 重载构造方法
+    public Car(String licensePlate, String brand, String model) {
+        this(licensePlate, brand, model, 300.0);
+    }
+
+    // Getter/Setter
+    public String getLicensePlate() { return licensePlate; }
+    public String getBrand() { return brand; }
+    public void setBrand(String brand) { this.brand = brand; }
+    public String getModel() { return model; }
+    public void setModel(String model) { this.model = model; }
+    public double getDailyRent() { return dailyRent; }
+
+    public void setDailyRent(double dailyRent) {
+        if (dailyRent > 0) {
+            this.dailyRent = dailyRent;
+        } else {
+            System.out.println("日租金必须大于0，设置失败！");
+        }
+    }
+
+    public boolean isRented() { return isRented; }
+
+    // 租车方法
+    public void rentCar() {
+        if (isRented) {
+            System.out.println("车辆已租出，无法再次租用！");
+        } else {
+            isRented = true;
+            System.out.println("车辆已成功租出！");
+        }
+    }
+
+    // 还车方法
+    public void returnCar() {
+        if (!isRented) {
+            System.out.println("车辆未被租用，无需归还！");
+        } else {
+            isRented = false;
+            System.out.println("车辆已成功归还！");
+        }
+    }
+
+    // 计算租金
+    public double calculateRent(int days) {
+        return dailyRent * days;
+    }
+
+    // 静态方法：获取总车辆数
+    public static int getTotalCars() {
+        return totalCars;
+    }
+
+    // 打印车辆信息
+    public void displayInfo() {
+        System.out.println("车牌号：" + licensePlate +
+                " | 品牌：" + brand +
+                " | 型号：" + model +
+                " | 日租金：" + dailyRent +
+                " | 状态：" + (isRented ? "已出租" : "可租"));
+    }
+}

w3/TestCar.java

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+public class TestCar {
+    public static void main(String[] args) {
+        // 创建3个Car对象
+        Car car1 = new Car("京A12345", "特斯拉", "Model 3", 280.0);
+        Car car2 = new Car("沪B67890", "比亚迪", "汉EV");
+        Car car3 = new Car("粤C24680", "丰田", "凯美瑞", 220.0);
+
+        // 输出车辆信息
+        System.out.println("=== 所有车辆信息 ===");
+        car1.displayInfo();
+        car2.displayInfo();
+        car3.displayInfo();
+        System.out.println("总车辆数：" + Car.getTotalCars());
+
+        // 测试租车/还车
+        System.out.println("\n=== 测试租车/还车 ===");
+        car1.rentCar();
+        car1.rentCar();
+        car1.returnCar();
+        car1.returnCar();
+
+        // 测试租金计算
+        System.out.println("\n=== 测试租金计算 ===");
+        double rent = car2.calculateRent(5);
+        System.out.println("租用5天总租金：" + rent + "元");
+
+        // 测试日租金校验
+        System.out.println("\n=== 测试日租金校验 ===");
+        car3.setDailyRent(-100.0); // 改为double类型字面量
+        System.out.println("修改后日租金：" + car3.getDailyRent());
+    }
+}