From a6c31111f50251053c49726fc0d6a76bdeea6765 Mon Sep 17 00:00:00 2001
From: Luojiale <2272532647@qq.com>
Date: Mon, 23 Mar 2026 10:19:45 +0800
Subject: [PATCH] =?UTF-8?q?=E8=BD=A6=E8=BE=86=E7=AE=A1=E7=90=86=E7=B3=BB?=
 =?UTF-8?q?=E7=BB=9F=E4=B8=AD=E7=9A=84Car=E7=B1=BB?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 w1/Student.java |   0
 w3/Car.java     | 113 ++++++++++++++++++++++++++++++++++++++++++++++++
 w3/TestCar.java |  35 +++++++++++++++
 3 files changed, 148 insertions(+)
 create mode 100644 w1/Student.java
 create mode 100644 w3/Car.java
 create mode 100644 w3/TestCar.java

diff --git a/w1/Student.java b/w1/Student.java
new file mode 100644
index 0000000..e69de29
diff --git a/w3/Car.java b/w3/Car.java
new file mode 100644
index 0000000..6a70709
--- /dev/null
+++ b/w3/Car.java
@@ -0,0 +1,113 @@
+public class Car {
+    // 1. 私有属性
+    private final String licensePlate; // 车牌号（不可变）
+    private String brand;              // 品牌
+    private String model;              // 型号
+    private double dailyRent;          // 日租金
+    private boolean isRented;          // 是否已出租
+
+    // 静态变量：统计车辆总数
+    private static int totalCars = 0;
+
+    // 2. 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); // 通过setter校验租金
+        this.isRented = false;   // 初始状态：未出租
+        totalCars++;             // 每创建一个对象，总数+1
+    }
+
+    // 3. 三参构造方法（调用全参构造，日租金默认300元）
+    public Car(String licensePlate, String brand, String model) {
+        this(licensePlate, brand, model, 300.0);
+    }
+
+    // 4. Getter/Setter 方法
+    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 setter：必须校验是否大于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;
+    }
+
+    // 注意：isRented 不提供 setter，只能通过业务方法修改状态
+
+    // 5. 业务方法
+    // 租车：将状态置为已出租
+    public void rentCar() {
+        if (isRented) {
+            System.out.println("车辆 " + licensePlate + " 已出租，无法再次租用！");
+        } else {
+            isRented = true;
+            System.out.println("车辆 " + licensePlate + " 已成功出租！");
+        }
+    }
+
+    // 还车：将状态置为未出租
+    public void returnCar() {
+        if (!isRented) {
+            System.out.println("车辆 " + licensePlate + " 未被租用，无需归还！");
+        } else {
+            isRented = false;
+            System.out.println("车辆 " + licensePlate + " 已成功归还！");
+        }
+    }
+
+    // 计算总租金：日租金 × 天数（假设天数>0）
+    public double calculateRent(int days) {
+        if (days > 0) {
+            return dailyRent * days;
+        } else {
+            System.out.println("租赁天数必须大于0！");
+            return 0.0;
+        }
+    }
+
+    // 6. 静态方法：获取总车辆数
+    public static int getTotalCars() {
+        return totalCars;
+    }
+
+    // 辅助方法：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 + " 元/天");
+        System.out.println("状态：" + (isRented ? "已出租" : "可租"));
+        System.out.println("================");
+    }
+}
\ No newline at end of file
diff --git a/w3/TestCar.java b/w3/TestCar.java
new file mode 100644
index 0000000..6cb34e4
--- /dev/null
+++ b/w3/TestCar.java
@@ -0,0 +1,35 @@
+public class TestCar {
+    public static void main(String[] args) {
+        // 创建3个Car对象（使用不同构造方法）
+        Car car1 = new Car("京A12345", "丰田", "凯美瑞", 280.0);
+        Car car2 = new Car("沪B67890", "本田", "雅阁"); // 日租金默认300元
+        Car car3 = new Car("粤C11111", "大众", "帕萨特", 320.0);
+
+        // 打印所有车辆信息
+        System.out.println("=== 初始车辆信息 ===");
+        car1.displayInfo();
+        car2.displayInfo();
+        car3.displayInfo();
+
+        // 测试租车/还车业务
+        System.out.println("\n=== 测试租车/还车 ===");
+        car1.rentCar();    // 第一次租车
+        car1.rentCar();    // 重复租车（提示已出租）
+        car1.returnCar();  // 第一次还车
+        car1.returnCar();  // 重复还车（提示未出租）
+
+        // 计算租金
+        System.out.println("\n=== 计算租金 ===");
+        double rent = car1.calculateRent(5);
+        System.out.println("车辆 " + car1.getLicensePlate() + " 租赁5天，总租金：" + rent + " 元");
+
+        // 测试setDailyRent非法值
+        System.out.println("\n=== 测试日租金非法值 ===");
+        car1.setDailyRent(-100); // 非法值，提示错误
+        System.out.println("修改后日租金：" + car1.getDailyRent() + " 元/天");
+
+        // 测试静态变量
+        System.out.println("\n=== 车辆总数 ===");
+        System.out.println("当前系统中车辆总数：" + Car.getTotalCars() + " 辆");
+    }
+}
\ No newline at end of file