java/w3/Car.java

package com.rental;

public class Car {
    // 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;            // 租出状态
    
    // 静态变量（选做）
    private static int totalCars = 0;
    
    // 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;
        this.dailyRent = dailyRent;
        this.isRented = false;  // 初始化为未租出
        totalCars++;  // 创建车辆时总数加1
    }
    
    // 三参构造方法（日租金使用默认值300）
    public Car(String licensePlate, String brand, String model) {
        this(licensePlate, brand, model, 300.0);  // 调用全参构造
    }
    
    // Getter方法
    public String getLicensePlate() {
        return licensePlate;
    }
    
    public String getBrand() {
        return brand;
    }
    
    public String getModel() {
        return model;
    }
    
    public double getDailyRent() {
        return dailyRent;
    }
    
    public boolean isRented() {
        return isRented;
    }
    
    // Setter方法
    public void setBrand(String brand) {
        this.brand = brand;
    }
    
    public void setModel(String model) {
        this.model = model;
    }
    
    public void setDailyRent(double dailyRent) {
        if (dailyRent > 0) {
            this.dailyRent = dailyRent;
        } else {
            System.out.println("错误：日租金必须大于0，保持原值：" + this.dailyRent);
        }
    }
    
    // 业务方法：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("车辆 " + licensePlate + " 租用成功");
        }
    }
    
    // 业务方法：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("车辆 " + licensePlate + " 归还成功");
        }
    }
    
    // 业务方法：计算租金
    public double calculateRent(int days) {
        return dailyRent * days;
    }
    
    // 显示车辆信息的方法
    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("租出状态：" + (isRented ? "已租出" : "未租出"));
        System.out.println("================================");
    }
    
    // 静态方法
    public static int getTotalCars() {
        return totalCars;
    }
}