关于租车的实现，结构上有什么问题，求指导

Question

package muke.stu.one;

import java.util.Scanner;

import muke.stu.one.entity.Car;
import muke.stu.one.entity.Coatch;
import muke.stu.one.entity.Pika;
import muke.stu.one.entity.Truck;

public class rentCar {
    static Scanner in = new Scanner(System.in);
    public static void main(String[] args) {
        Boolean isRentCar = false;
        int carNum = 0;
        String rentInformation = null;
        Car[] carInit = {new Pika("皮卡",2,6,1200), new Truck("大货车",20,800),new Coatch("客车",20,1000),new Pika("破皮卡",3,5,800),
                        new Coatch("破客车",25,1000)};
        
        System.out.println("是否需要租车：1.是     2.否");
        int rentCar = in.nextInt();
        if(rentCar == 1){
            isRentCar = true;
        }
        if(isRentCar){
            System.out.println("租用几辆车：");
            carNum = in.nextInt();
            rentInformation = rent(carNum,carInit);
            System.out.println("您的租车信息："+"\n"+rentInformation);
        }
        System.out.println("谢谢使用");
    }
    //租车界面
    public static String rent(int carNum,Car[] carArray){
        String rentInformation = null;
        int carID;
        double cost =0.0;
        int  people=0;
        int capacity=0;
        int days =0;
        String addPeople ="";
        String addCapacity="";
        //展示车辆信息
        System.out.println("序号 \t类型 \t容量 \t价格(元/天)");
        for(int i=0;i<carArray.length;i++){
            System.out.println(i+1+"\t"+carArray[i].getType()
                            +"\t"+carArray[i].getContent()+"\t"+carArray[i].getPrice());
        }
        //获取选择车辆
        for(int m=0;m<carNum;m++){
            System.out.println("请输入您需要车辆序号：");
            carID=in.nextInt();
            Car carRent =carArray[carID-1];
            if(carRent instanceof Pika){
                cost += carRent.getPrice();
                people += ((Pika) carRent).getManned();
                capacity += ((Pika) carRent).getCapacity();
                addPeople += carRent.getType()+"\t";
                addCapacity += carRent.getType()+"\t";
            }else if(carRent instanceof Truck){
                cost += carRent.getPrice();
                capacity += ((Truck) carRent).getCapacity();
                addCapacity += carRent.getType()+"\t";
            }else{
                cost += carRent.getPrice();
                people += ((Coatch) carRent).getManned();
                addPeople += carRent.getType()+"\t";
            }
        }
        System.out.println("请输入您需要租借的天数");
        days= in.nextInt();
        cost = cost*days;
        //格式化租车信息
        rentInformation ="您租用载人的车有："+"\n"+addPeople+"共载人："+people+"\n" 
                +"您租用货物的车有："+"\n"+addCapacity+"共载货物："+capacity+"\n"
                +"您租车："+days+"天"+"\t"+"共花费："+cost+"元";
        return rentInformation;
    }

}




package muke.stu.one.entity;

public class Car {
    //名字，类型
    private String type;
    //价钱
    private double price;
    //容量
    private String content;
    public String getContent() {
        return content;
    }
    public void setContent(String content) {
        this.content = content;
    }
    public String getType() {
        return type;
    }
    public void setType(String type) {
        this.type = type;
    }
    public double getPrice() {
        return price;
    }
    public void setPrice(double price) {
        this.price = price;
    }
    
}

package muke.stu.one.entity;

import muke.stu.one.serivce.transportGoods;
import muke.stu.one.serivce.transportPeople;

public class Pika extends Car implements transportGoods,transportPeople{
    private int capacity;
    private int manned;
    
    public int getCapacity() {
        return capacity;
    }
    public void setCapacity(int capacity) {
        this.capacity = capacity;
    }
    public int getManned() {
        return manned;
    }
    public void setManned(int manned) {
        this.manned = manned;
    }
    public Pika(){
        super();
    }
    public Pika(String type,int manned,int capacity,double price){
        this.setType(type);
        this.setCapacity(capacity);
        this.setManned(manned);
        this.setPrice(price);
        this.setContent(transportPeople()+transportGoods());
    }
    
    
    @Override
    public String transportPeople() {
        String transportPeople ="载人量:"+this.getManned();
        return transportPeople;
        
    }

    @Override
    public String transportGoods() {
        String transportGoods="载货量："+this.getCapacity();
        return transportGoods;
    }
    
}

package muke.stu.one.entity;

import muke.stu.one.serivce.transportPeople;

public class Coatch extends Car implements transportPeople{

    private int manned;

    public int getManned() {
        return manned;
    }
    public void setManned(int manned) {
        this.manned = manned;
    }
    public Coatch(){
        super();
    }
    public Coatch(String type,int manned,double price){
        this.setType(type);
        this.setManned(manned);
        this.setPrice(price);
        this.setContent(transportPeople());
    }
    @Override
    public String transportPeople() {
        String transportPeople ="载人量:"+this.getManned();
        return transportPeople;
        
    }
}
package muke.stu.one.entity;

import muke.stu.one.serivce.transportGoods;

public class Truck extends Car implements transportGoods{
    private int capacity;
    public int getCapacity() {
        return capacity;
    }
    public void setCapacity(int capacity) {
        this.capacity = capacity;
    }
    public Truck(){
        super();
    }
    public Truck(String type,int capacity,double price){
        this.setType(type);
        this.setCapacity(capacity);
        this.setPrice(price);
        this.setContent(transportGoods());
    }
    @Override
    public String transportGoods() {
        String transportGoods="载货量："+this.getCapacity();
        return transportGoods;
    }
    
}
package muke.stu.one.serivce;

public interface transportGoods {
    public String transportGoods();
}
package muke.stu.one.serivce;

public interface transportPeople {
    public  String transportPeople();
}

Answer 1

哪里出错了，这么多怎么看，