更新w3文件夹的Car类相关代码

w3/Car.java

@@ -0,0 +1,107 @@
+package com.rental;
+
+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
+    public Car(String licensePlate, String brand, String model, double dailyRent) {
+        this.licensePlate = licensePlate;
+        this.brand = brand;
+        this.model = model;
+        setDailyRent(dailyRent); // 用setter自带校验
+        this.isRented = false;
+        totalCars++;
+    }
+
+    // 重载构造：默认日租金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;
+    }
+
+    // 租金必须>0
+    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
+    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("租车成功！");
+        }
+    }
+
+    // 还车
+    public void returnCar() {
+        if (!isRented) {
+            System.out.println("车辆未被租用，无需归还");
+        } else {
+            isRented = false;
+            System.out.println("还车成功！");
+        }
+    }
+
+    // 计算租金
+    public double calculateRent(int days) {
+        return dailyRent * days;
+    }
+
+    // 静态方法：获取车辆总数
+    public static int getTotalCars() {
+        return totalCars;
+    }
+
+    // 打印车辆信息
+    public void displayInfo() {
+        System.out.println("=====车辆信息=====");
+        System.out.println("车牌号：" + licensePlate);
+        System.out.println("品牌：" + brand);
+        System.out.println("型号：" + model);
+        System.out.println("日租金：" + dailyRent);
+        System.out.println("是否租出：" + (isRented ? "是" : "否"));
+        System.out.println("==================\n");
+    }
+}

w3/TestCar.java

@@ -0,0 +1,34 @@
+package com.rental;
+
+public class TestCar {
+    public static void main(String[] args) {
+        // 创建3辆车，使用不同构造
+        Car car1 = new Car("京A12345", "丰田", "Camry", 260);
+        Car car2 = new Car("沪B67890", "大众", "Magotan");
+        Car car3 = new Car("粤C98765", "比亚迪", "Han", 350);
+
+        // 打印信息
+        car1.displayInfo();
+        car2.displayInfo();
+        car3.displayInfo();
+
+        // 测试租车/还车重复操作
+        System.out.println("===测试车辆1租车===");
+        car1.rentCar();
+        car1.rentCar();
+
+        System.out.println("===测试车辆1还车===");
+        car1.returnCar();
+        car1.returnCar();
+
+        // 计算5天租金
+        System.out.println("\n车辆2租用5天费用：" + car2.calculateRent(5));
+
+        // 测试非法租金
+        System.out.println("\n===尝试设置非法租金===");
+        car3.setDailyRent(-100);
+
+        // 静态变量：总车辆数
+        System.out.println("\n系统总车辆数：" + Car.getTotalCars());
+    }
+}