java/w3/w3car

package com.rental;

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
    public Car(String licensePlate, String brand, String model, double dailyRent) {
        this.licensePlate = licensePlate;
        this.brand = brand;
        this.model = model;
        this.dailyRent = dailyRent;
        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; }

    public void setDailyRent(double dailyRent) {
        if (dailyRent > 0) {
            this.dailyRent = dailyRent;
        } else {
            System.out.println("日租金必须大于0，修改失败！");
        }
    }

    public boolean isRented() { return isRented; }

    // 业务方法
    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");
        }
    }

    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");
        }
    }

    public double calculateRent(int days) {
        return dailyRent * days;
    }

    public void displayInfo() {
        System.out.println("车牌号：" + licensePlate +
                "，品牌：" + brand +
                "，型号：" + model +
                "，日租金：" + dailyRent +
                "元/天，状态：" + (isRented ? "已租出" : "可租"));
    }

    public static int getTotalCars() {
        return totalCars;
    }
}