java/w3/Car.java

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");
    }
}