多态初步认识

首先创建父类，因为BYD和BMW同输入汽车，有共同的属性和方法
 1 public class Car {
    int price;
    String type;
    String color;
    public Car() {
        super();
    }
    public Car(int price, String type, String color) {
        super();
        this.price = price;
        this.type = type;
        this.color = color;
    }
    
    public void show(){
        System.out.println("I can run!");
    }
}

创建BYD子类，并重写方法
 1 public class BYD extends Car {
    
    public BYD() {
        super();
    }

    public BYD(int price, String type, String color) {
        super(price, type, color);
    }

    public void show(){
        System.out.println("BYD");
        System.out.println("价格"+price);
        System.out.println("型号"+type);
        System.out.println("颜色"+color);
    }
}

public class BMW extends Car {
    
    public BMW() {
        super();
    }

    public BMW(int price, String type, String color) {
        super(price, type, color);
    }

    public void show(){
        System.out.println("BMW");
        System.out.println("价格"+price);
        System.out.println("型号"+type);
        System.out.println("颜色"+color);
    }
}

静态和非静态的问题也要注意，到底是谁调用
 1 public class Driver {
    static String name;
    
    public Driver(String sex) {
        this.name = name;
    }
    public Driver() {
    }
    /*
     * 创建方法
     */
    public static void drive(Car A){//static?
        System.out.println(name+"Let's run!");
        A.show();
    }
    
    public static void main(String[] args) {
        Driver driver=new Driver("张三");
        Car byd=new BYD(3000000,"唐","红");
        driver.drive(byd);//这样调用可以不是static
        Car bmw=new BMW(8000000,"x5","黑");
        Driver.drive(bmw);//这样调用必须是static
    }
}