面向对象---多态(代码片段)

//类名  对象名  = new   类名（）；
  Dog  d = new Dog();
  

  Penguin  p = new Penguin();

//语法
Pet  dog=new Dog();

//语法
Dog dog=(Dog)pet

//汽车类
public abstract class MotoVehicle 
    //车牌号   品牌  日租金
private  String no;
private   String brand;
private   int perRent;


//构造方法：车牌号   品牌  日租金

public MotoVehicle(String no, String brand, int perRent) 
    this.no = no;
    this.brand = brand;
    this.perRent = perRent;
                
//set/get方法
public String getNo() 
    return no;


public void setNo(String no) 
    this.no = no;



public String getBrand() 
    return brand;



public void setBrand(String brand) 
    this.brand = brand;


public int getPerRent() 
    return perRent;


public void setPerRent(int perRent) 
    this.perRent = perRent;





//抽象方法:计算租金
public abstract float calcRent(int days);

//轿车类
public  class Car extends MotoVehicle
    private String type;
    //构造方法：车牌号   品牌  日租金  类型
    public Car(String no, String brand, int perRent,String type) 
    super(no,brand,perRent);
    this.type=type;
    
    //set/get方法
    public String getType() 
        return type;
    

    public void setType(String type) 
        this.type = type;
    

    @Override
    public float calcRent(int days) 
        float price=this.getPerRent()*days;
        if(days>7&&days<=30)          //大于7天小于30天9折
            price*=0.9f;
        else if(days>30&&days<=150)
            price*=0.8f;
        else if(days>150)
            price*=0.7f;
        
        return price;
    
    

public class bus extends MotoVehicle 
    //私有属性座位
private int seatCount;
//构造方法：车牌号   品牌  日租金  座位
public bus(String no, String brand, int perRent,int seatCount)
    super(no,brand,perRent);
    this.seatCount=seatCount;


//set/get方法
public int getSeatCount() 
    return seatCount;


public void setSeatCount(int seatCount) 
    this.seatCount = seatCount;

@Override
public float calcRent(int days) 
    float price=this.getPerRent()*days;
    if(days>3&&days<=7)
        price*=0.9f;
    else if(days>=7&&days<30)
        price*=0.8f;
    else if(days>=30&&days<=150)
        price*=0.7f;
    else if(days>=150)
        price*=0.6f;
    
    return price;

public class VehicleOperation 
    //汽车业务类
MotoVehicle []motoVehicle=new MotoVehicle[5];
//汽车数组
//初始化几个汽车信息
public void show()
    motoVehicle[0]=new Car("苏A6666","宝马",800,"520i");
    motoVehicle[1]=new Car("苏A1111","宝马",500,"x6");
    motoVehicle[2]=new Car("苏A2222","别克",600,"林荫大道");
    motoVehicle[3]=new Car("苏A8888","宝马",710,"GL8");
    motoVehicle[4]=new bus("苏A9999","金龙",800,24);


//父类类型作为返回值
//租车   
//参数   品牌   座位数   型号    
public MotoVehicle rentMontoVehicle(String brand,int seatCount,String type)
    MotoVehicle v= null;
    //循环是小汽车还是大巴车
    for(MotoVehicle motovehicle:motoVehicle)
        if( motovehicle instanceof Car)
            Car car=(Car) motovehicle;  //向下转型
            //轿车品牌和型号与用户想要的品牌信号吻合
            if(car.getBrand().equals(brand)&&car.getType().equals(type))
                v=car;
                break;
            
        else
            bus b=(bus)motovehicle;
            if(b.getBrand().equals(brand)&&b.getSeatCount()==seatCount)
                v=b;
                break;
            
            
        
    
    return v;
    

//汽车租赁系统测试类
public class TestRent 
public static void main(String[] args) 
    Scanner input=new Scanner(System.in);
    
    System.out.println("*********欢迎来到汽车租赁公司！**********");
    System.out.print("请选择亲您需要租赁的车型：1、轿车  2、客车");
    int vehicleType=input.nextInt();
    //获取用户租赁汽车的三个条件;:品牌    座位数   型号
    String brand="";
    int seatCount=0;
    String type="";
    switch( vehicleType)
    case 1:
        System.out.print("请选择您要租赁的汽车品牌: 1、别克    2、宝马");
        int choose =input.nextInt();
        if(choose==1)
            brand="别克";
            System.out.print("请选择您需要租赁的类型：1、林荫大道   2、GL8");
            type=(input.nextInt()==1)?"林荫大道":"GL8";
        else
            
            brand="宝马";
            System.out.print("请选择您需要租赁的类型：1、x6   2、520i");
            type=(input.nextInt()==1)?"x6":"520i";
        
        break;
    case 2:
        System.out.println("请选择您要租赁的汽车品牌：1、金杯    2、金龙");
        brand =(input.nextInt()==1)?"金杯":"金龙";
        System.out.println("请选择需要租赁的座位数：");
        seatCount=(input.nextInt()==1)?16:34;
                break;
    
    
    VehicleOperation vehicleOper=new     VehicleOperation();
    vehicleOper.show();
    MotoVehicle m=vehicleOper.rentMontoVehicle(brand, seatCount, type);
    System.out.println("请输入您需要租赁的天数：");
    int days=input.nextInt();
    float price=m.calcRent(days);
    System.out.println("您的汽车车牌号为："+m.getNo());
    System.out.println("您需要支付租赁费用："+price+"元");