租车系统，可以再加输入校验进行完善

Car.java

public class Car {
    int num;
    String name;
    double rentPrice;//租车单价
    int capacityForPeople;//载人数量
    double capacityForCargo;//载客数量

    public int  capPeople(){
        return capacityForPeople;
    }

    public double capCargo(){
        return capacityForCargo;
    }

    public double totalPrice(int day){
        return rentPrice*day;
    }

}

Audi.java

package jimsty.test.carrental;

public class Audi extends Car {
    {
        num = 1;
        name = "奥迪A4";
        rentPrice = 500.0;
        capacityForPeople = 4;
        capacityForCargo = 0;

    }
}

Chevrolet .java

package jimsty.test.carrental;

public class Chevrolet extends Car {
    {
        num = 3;
        name = "皮卡雪6";
        rentPrice = 450.0;
        capacityForPeople = 4;
        capacityForCargo = 2;

    }
}

Mazda.java

package jimsty.test.carrental;

public class Mazda extends Car {
    {
        num = 2;
        name = "马自达6";
        rentPrice = 400.0;
        capacityForPeople = 4;
        capacityForCargo = 0;

    }
}

KingLong.java

package jimsty.test.carrental;

public class KingLong extends Car {
    {
        num = 4;
        name = "金龙";
        rentPrice = 800.0;
        capacityForPeople = 20;
        capacityForCargo = 0;

    }
}

SongHuaJiang.java

package jimsty.test.carrental;

public class SongHuaJiang extends Car {
    {
        num = 5;
        name = "松花江";
        rentPrice = 400.0;
        capacityForPeople = 0;
        capacityForCargo = 4;

    }
}

Naveco.java

package jimsty.test.carrental;

public class Naveco extends Car {
    {
        num = 6;
        name = "依维柯";
        rentPrice = 1000.0;
        capacityForPeople = 0;
        capacityForCargo = 20;

    }
}

主程序
InterfaceUI.java

package jimsty.test.carrental;

import java.util.Scanner;

public class InterfaceUI {
    int rentNum = 0;// 租车数量
    int day = 0;// 租车天数
    int totalPeople = 0;
    double totalCargo = 0;
    double totalMoney = 0;

    public void run() {
        // 进入嗒嗒租车系统
        System.out.println("欢迎使用嗒嗒租车系统:");
        Scanner in = new Scanner(System.in);
        System.out.println("您是否要租车：1是 0否");
        int b = in.nextInt();
        if (b == 0) {
            in.close();
            return;
        }

        // 可租车属性显示
        System.out.println("你可租车的类型有:\n" + "序号    汽车名称      租金                  容量\n"
                + "1.  奥迪A4  500元/天          载人：4人\n" + "2.  马自达6  400元/天         载人：4人 \n"
                + "3.  皮卡雪6  450元/天         载人：4人 载货：2吨\n" + "4.  金龙            800元/天         载人：20人\n"
                + "5.  松花江        400元/天         载货：4吨\n" + "6.  依维柯        1000元/天       载货：20吨\n");

        // 租车数量类型判断
        System.out.println("请输入您要租汽车的数量：");
        rentNum = in.nextInt();
        if (rentNum <= 0) {
            System.out.println("输入有误，请输入您要租汽车的数量：");
        }
        int a[] = new int[rentNum];
        for (int i = 0; i < rentNum; i++) {
            System.out.println("请输入第" + (i + 1) + "辆车的序号：");
            a[i] = in.nextInt();
        }

        // 租车天数
        System.out.println("请输入租车天数：");
        day = in.nextInt();
        in.close();

        // 输出用户账单
        System.out.println("您的账单：");

        String displayCarForPeople = "";// 显示账单中的载人车型
        String displayCarForCargo = "";// 显示账单中的载货车型
        for (int i = 0; i < rentNum; i++) {

            switch (a[i]) {
            case 1: {
                Car car = new Audi();
                totalPeople = totalPeople + car.capPeople();
                displayCarForPeople = displayCarForPeople + car.name + " ";
                totalMoney = totalMoney + car.totalPrice(day);
                break;
            }
            case 2: {
                Car car = new Mazda();
                totalPeople = totalPeople + car.capPeople();
                displayCarForPeople = displayCarForPeople + car.name + " ";
                totalMoney = totalMoney + car.totalPrice(day);
                break;
            }
            case 3: {
                Car car = new Chevrolet();
                totalPeople = totalPeople + car.capPeople();
                totalCargo = totalCargo + car.capCargo();
                displayCarForPeople = displayCarForPeople + car.name + " ";
                displayCarForCargo = displayCarForCargo + car.name + " ";
                totalMoney = totalMoney + car.totalPrice(day);
                break;
            }
            case 4: {
                Car car = new KingLong();
                totalPeople = totalPeople + car.capPeople();
                displayCarForPeople = displayCarForPeople + car.name + " ";
                totalMoney = totalMoney + car.totalPrice(day);
                break;
            }
            case 5: {
                Car car = new SongHuaJiang();
                totalCargo = totalCargo + car.capCargo();
                displayCarForCargo = displayCarForCargo + car.name + " ";
                totalMoney = totalMoney + car.totalPrice(day);
                break;
            }
            case 6: {
                Car car = new Naveco();
                totalCargo = totalCargo + car.capCargo();
                displayCarForCargo = displayCarForCargo + car.name + " ";
                totalMoney = totalMoney + car.totalPrice(day);
                break;
            }

            }

        }
        System.out.println("***可载人的车有：\n" + displayCarForPeople + "共载人：" + totalPeople + "人");
        System.out.println("***载货的车有：\n" + displayCarForCargo + "" + totalCargo + "吨");

        System.out.println("***租车总价格：" + totalMoney + "元");

    }

    public static void main(String[] args) {
        InterfaceUI ui = new InterfaceUI();
        ui.run();
    }

}