做项目要的就是最少的代码实现最多的功能，而且用最简单的知识来实现它。
------玄鉴

//父类——车。省略了set/get方法

public class Che {
private String brand;
static int day;
private int daymoney;
private int price;

public int priceAll(int day){
price= this.day*daymoney;
return price;
};

//子类轿车。省略了set/get方法

public class Car extends Che {

private String type;

@Override
public int priceAll(int day) {

return getDaymoney()*day;

}

——————————————

子类——客车。省略了set/get方法
public class Bus extends Che {

private int seat;

@Override
public int priceAll(int day) {

return  getDaymoney()*day;
}

——————————

流程测试类。

public class Liucheng {

/**
 * @param args
 */
public static void main(String[] args) {

    Scanner in = new Scanner(System.in);
    System.out.println("欢迎来到汽车租赁公司");
    System.out.println("请输入要租赁的天数：");

    Che che = new Che();
    Car car = new Car();
    Bus bus = new Bus();

    int sum = 0;
    int aa = in.nextInt();
    che.setDay(aa);

    do {

        System.out.println("请输入要租赁的汽车类型（1.轿车  2，客车   ）");

        switch (in.nextInt()) {
        case 1:// 轿车
            System.out.println("请你选择品牌：（1，宝马   2.别克）");
            switch (in.nextInt()) {
            case 1:// 宝马

                car.setType("宝马550i");
                car.setDaymoney(500);
                System.out.println("租金为：" + car.priceAll(car.getDay()));// 验证是否设置成功

                break;
            case 2:// 别克
                che.setBrand("别克");
                System.out.println("请选择别克轿车型号：（1.别克商务舱Gl8  2.别克林荫大道）");
                switch (in.nextInt()) {
                case 1:// 商务
                    car.setType("别克商务舱Gl82");
                    car.setDaymoney(600);
                    System.out.println("租金为：" + car.priceAll(che.getDay()));

                    break;
                case 2:// 林荫大道
                    car.setType("别克林荫大道");
                    car.setDaymoney(300);
                    System.out.println("租金为：" + car.priceAll(car.getDay()));

                    break;

                default:
                    System.out.println("输入错误请重新输入。");
                    break;
                }
                break;

            default:
                System.out.println("输入错误请重新输入。");

                break;
            }
            break;
        case 2:// 客车
            System.out.println("请选择座位数：");

            bus.setSeat(in.nextInt());
            if (bus.getSeat() >= 16) {
                bus.setDaymoney(1500);

            } else {
                bus.setDaymoney(800);

            }
            System.out.println("请选择品牌：（1，金杯2.宇通）");
            switch (in.nextInt()) {
            case 1:
                bus.setBrand("金杯");
                System.out.println("租金为：" + bus.priceAll(bus.getDay()));

                break;
            case 2:
                bus.setBrand("宇通");
                System.out.println("租金为：" + bus.priceAll(che.getDay()));

                break;

            default:
                System.out.println("输入错误请重新输入。");
                break;
            }

            break;

        default:
            System.out.println("输入错误请重新输入。");
            break;
        }
        sum = sum + car.priceAll(aa) + bus.priceAll(aa);
        System.out.println("请问要继续租赁吗？");
    } while (in.next().equals("y"));

    System.out.println("总租金为：" + sum);
}

}