Vehicle.java

package com.imooc;

public class Vehicle {
    public int id;
    public String name;
    public int price;
    public int getPrice() {
        return price;
    }
}

Car.java

package com.imooc;

public class Car extends Vehicle implements IPeople {
    public int Num;

    public Car(int id,String name,int price,int Num){
        this.id=id;
        this.name=name;
        this.price=price;
        this.Num=Num;
    }
    public String toString(){
        return id+"\t"+name+"\t"+price+"元/天\t"+Num+"人";
    }

    @Override
    public int getPeople() {
        // TODO Auto-generated method stub
        return Num;
    }
}

Truck.java

package com.imooc;

public class Truck extends Vehicle implements ICargo {
    public int Weight;
    public Truck(int id,String name,int price,int Weight){
        this.id=id;
        this.name=name;
        this.price=price;
        this.Weight=Weight;
    }
    public String toString(){
        return id+"\t"+name+"\t"+price+"元/天\t"+Weight+"吨";
    }
    @Override
    public int getCargo() {
        // TODO Auto-generated method stub
        return Weight;
    }
}

Pickup.java

package com.imooc;

public class Pickup extends Vehicle implements IPeople, ICargo {
    public int Num;
    public int Weight;
    public Pickup(int id,String name,int price,int Num,int Weight){
        this.id=id;
        this.name=name;
        this.price=price;
        this.Num=Num;
        this.Weight=Weight;
    }
    public String toString(){
        return id+"\t"+name+"\t"+price+"元/天\t"+Num+"人,"+Weight+"吨";
    }
    @Override
    public int getCargo() {
        // TODO Auto-generated method stub
        return Weight;
    }

    @Override
    public int getPeople() {
        // TODO Auto-generated method stub
        return Num;
    }

}

ICargo.java

package com.imooc;

public interface ICargo {
    public int getCargo();
}

IPeople.java

package com.imooc;

public interface IPeople {
    public int getPeople();
}

RentSystem.java

package com.imooc;
import java.util.Scanner;

public class RentSystem {
    int rentSum=0;
    String PeopleVehicle="",cargoVehicle="";

    public void method(){
        Vehicle[] Vehicles={new Car(1,"奥迪A4",500,4),
                new Car(2,"马自达6",400,4),
                new Pickup(3,"皮卡雪6",450,4,2),
                new Car(4,"金龙",800,20), 
                new Truck(5,"松花江",400,4), 
                new Truck(6,"依维柯",1000,20)};
        System.out.println("welcome to RentSystem");
        System.out.println("Which car do you like to pick:1.car;2.truck;3.pickup;4.no need.");
        Scanner input1=new Scanner(System.in);
        switch (input1.nextInt()){
        case 4:{
            System.out.println("quit!");
            System.exit(0);
            break;
        }
        case 1:{
            for(int i=0;i<Vehicles.length;i++){
                if(Vehicles[i].getClass()==Car.class){
                    System.out.println(Vehicles[i]);
                }   
            }
            break;
        }
        case 2:{
            for(int i=0;i<Vehicles.length;i++){
                if(Vehicles[i].getClass()==Truck.class){
                    System.out.println(Vehicles[i]);
                }   
            }   
            break;
        }
        case 3:{
            for(int i=0;i<Vehicles.length;i++){
                if(Vehicles[i].getClass()==Pickup.class){
                    System.out.println(Vehicles[i]);
                }   
            }
            break;
        }
        default:
            System.out.println("Wrong Input!");
            System.exit(0);
        }
        System.out.println("Which one:");
        Scanner input2=new Scanner(System.in);
        int idNum=input2.nextInt();
        System.out.println("How long:");
        Scanner input3=new Scanner(System.in);
        int day=input3.nextInt();
        rentSum=day*Vehicles[idNum-1].getPrice();
        System.out.println("Totally:"+rentSum+"元");

    }

    public static void main(String[] args) {
        RentSystem service = new RentSystem();
        int quit=0;
        do{
            service.method();
            System.out.println("Do you like to pick another one?1.yes,2.no");
            Scanner input0=new Scanner(System.in);
            quit=input0.nextInt();
        }while(quit==1);
        System.out.println("quit!1");

    }
}

参考了前面人的代码，做了简单的实现，两个接口获得载货和载客量没有用上，主程序控制部分还有优化空间