diff --git a/w3/Car.java b/w3/Car.java
new file mode 100644
index 0000000..138acf3
--- /dev/null
+++ b/w3/Car.java
@@ -0,0 +1,105 @@
+public class Car {
+    // 私有属性
+    private final String licensePlate; // 车牌号不可变
+    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); // 借用setter做校验
+        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;
+    }
+
+    // 日租金必须>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;
+    }
+
+    // 业务方法：租车
+    public void rentCar() {
+        if (!isRented) {
+            isRented = true;
+            System.out.println(licensePlate + " 租车成功！");
+        } else {
+            System.out.println(licensePlate + " 车辆已租出，无法再次租用");
+        }
+    }
+
+    // 业务方法：还车
+    public void returnCar() {
+        if (isRented) {
+            isRented = false;
+            System.out.println(licensePlate + " 还车成功！");
+        } else {
+            System.out.println(licensePlate + " 车辆未被租用，无需归还");
+        }
+    }
+
+    // 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");
+    }
+}
diff --git a/w3/README.md b/w3/README.md
new file mode 100644
index 0000000..78aab32
--- /dev/null
+++ b/w3/README.md
@@ -0,0 +1,11 @@
+实验目的
+
+1.掌握 Java 封装思想，使用 private 修饰属性，通过 getter/setter 访问。
+
+2.练习构造方法重载与 this() 调用。
+
+3.学会在 setter 和业务方法中做数据合法性校验。
+
+4.练习静态变量与静态方法实现全局统计。
+
+5.编写测试类验证类功能。
\ No newline at end of file
diff --git a/w3/TestCar.java b/w3/TestCar.java
new file mode 100644
index 0000000..0156e5d
--- /dev/null
+++ b/w3/TestCar.java
@@ -0,0 +1,34 @@
+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", 280);
+        Car car2 = new Car("沪B67890", "大众", "Magotan");
+        Car car3 = new Car("粤C54321", "比亚迪", "汉", 350);
+
+        // 打印信息
+        car1.displayInfo();
+        car2.displayInfo();
+        car3.displayInfo();
+
+        // 测试租车、重复租车、还车、重复还车
+        System.out.println("===测试car1租车还车===");
+        car1.rentCar();
+        car1.rentCar();
+        car1.returnCar();
+        car1.returnCar();
+        System.out.println();
+
+        // 计算5天租金
+        System.out.println("car2 租赁5天费用：" + car2.calculateRent(5));
+        System.out.println();
+
+        // 测试非法日租金
+        System.out.println("===尝试设置非法日租金===");
+        car3.setDailyRent(-100);
+        System.out.println("设置后car3日租金：" + car3.getDailyRent());
+        System.out.println();
+
+        // 静态总数
+        System.out.println("系统总车辆数：" + Car.getTotalCars());
+    }
+}