交作业，请大神指点如何继续优化，不胜感激

抽象类car

import java.util.*;
public abstract class Car {
 public String name;
 public int num;
 public int person;
 public int loads;
 public int rent;
 public void setNum(int num) {
  this.num=num;
  }
 public int getNum() {
  return num;
  }
 public void setRent(int rent) {
  this.rent=rent;
  }
 public int getRent() {
  return rent;
  }
 public void setPerson(int person) {
  this.person=person;
    }
  public int getPerson() {
   return person;
 }
  public void setLoads(int loads) {
   this.loads=loads;
 }
  public int getLoads() {
   return loads;
 }
  public void setName(String name) {
   this.name=name;
  }
  public String getName() {
   return name;
  }
  
}
 子类轿车Auto 

public class Auto extends Car {
  public Auto(int num,String name,int person,int rent) {
      this.setNum(num);
      this.setName(name);
      this.setPerson(person);
      this.setRent(rent);
     }
  public String toString() {
   return (num+"\t"+name+"\t"+"载人"+person+"位"+"\t\t"+rent);
  }
}   

子类卡车Truck

public class Truck extends Car {

    public Truck(int num,String name,int loads,int rent) {
     this.setNum(num);
     this.setName(name);
     this.setLoads(loads);;
     this.setRent(rent);
    }
    public String toString() {
   return (num+"\t"+name+"\t"+"载货"+loads+"吨"+"\t\t"+rent);
  }
}

子类皮卡Van       

public class Van extends Car {
   public Van(int num,String name,int person,int loads,int rent) {
      this.setNum(num);
      this.setName(name);
      this.setPerson(person);
      this.setLoads(loads);
      this.setRent(rent);
     }
   public String toString() {
    return (num+"\t"+name+"\t"+"载人"+person+"位，载货"+loads+"吨\t"+rent);
   }
}

主程序

import java.util.Scanner;
public class Carsys {

    public static void main(String[] args) {
  // TODO Auto-generated method stub
       Scanner input=new Scanner(System.in);
       int rentNum=0;//租车数量
       int rentDay=0;//租车天数
        //初始化车辆列表
  Car cars[]=new Car[6];
  cars[0]= new Auto(1,"奥迪A4",4,500);
  cars[1]= new Auto(2,"马自达6",4,400);
  cars[2]= new Van(3,"皮卡雪6",4,2,450);
  cars[3]= new Auto(4,"金龙",20,800);
  cars[4]= new Truck(5,"松花江",4,400);
  cars[5]= new Truck(6,"依维柯",20,1000);
  cars[0].getName();
     System.out.println("您好！欢迎使用哒哒租车系统");
     while(true) {
     System.out.println("请选择：租车服务输入1,退出系统输入2");
      int a=input.nextInt();
     if(a==2) {
      System.out.println("谢谢使用，再见！");
      break;
      
     }else if(a==1){
      System.out.println("以下是租车列表：");
      System.out.println("编 号"+"\t类 型"+"\t容 量"+"\t\t日租金/天");
      for(Car each:cars) {
       System.out.println(each);
      }
      System.out.println("请输入您要租车的数量");
      rentNum=input.nextInt();
      Car rentCar[]=new Car[rentNum];
      int price=0;
      int totalPerson=0;
      int totalLoads=0;
      for(int i=0;i<rentNum;i++) {
       while(true) {
        System.out.println("请输入第"+(i+1)+"辆车的编号：");
        int b=input.nextInt();
        if(b>6||b<0) {
         System.out.println("输入有误");
        }else {
         rentCar[i]=cars[b-1];
         break;
        }
       }
      }
      for(int i=0;i<rentNum;i++) {
       totalPerson=totalPerson+rentCar[i].person;
      }
      for(int i=0;i<rentNum;i++) {
       totalLoads=totalLoads+rentCar[i].loads;
      }
      System.out.println("请输入租车天数");
      rentDay=input.nextInt();
      for(int i=0;i<rentNum;i++) {
       price=price+rentCar[i].rent*rentDay;
      }
      System.out.println("您的账单如下：");
      System.out.println("***可载人的车有：");
      for(int i=0;i<rentNum;i++) {
       if(rentCar[i].person!=0)
       System.out.println(rentCar[i].name);
      }
      System.out.println("共可载人"+totalPerson+"人");
      System.out.println("***可载货的车有：");
      for(int i=0;i<rentNum;i++) {
       if(rentCar[i].loads!=0)
       System.out.println(rentCar[i].name);
      }
      System.out.println("共可载货"+totalLoads+"吨");
      System.out.println("***租车总价格："+price+"元");
      System.out.println("感谢惠顾，欢迎下次光临！");
      break; 
     }else {
      System.out.println("输入有误，请重新输入");
     }
     }
     input.close();
 }
}