JAVA基础篇—抽象类，抽象方法

class Shape

package com.shape;

public abstract class Shape {
    double area;//
    double per;//
    String color;//
    public  Shape() {
    }
    public  Shape(String c){
        this.color=c;
    }
    abstract  double getArea();
    abstract  double getPer();
    abstract  void showAll();
    public  void getColor(String c){
        this.color=c;
        
    }
    
}

class Rectangle

package com.shape;

public class Rectangle  extends Shape{
    double Width;//
    double height;//
     
    @Override
    double getArea() {
        return super.area=Width*height;
    }

    @Override
    double getPer() {
        return super.per=Width*2+height*2;
    }

    @Override
    void showAll() {
        // TODO Auto-generated method stub
        System.out.println("���ε����Ϊ��"+getArea()+"�ܳ�Ϊ"+getPer());
    }
    public Rectangle(){}
    public  Rectangle(double w,double h){
        this.Width=w;
        this.height=h;
    } 

}

class Circle

package com.shape;

public class Circle  extends Shape{
    double radius;//�뾶

    @Override
    double getArea() {
        return super.area=radius*3.14*radius;
    }

    @Override
    double getPer() {
        return super.per=2*radius*3.14;
    }

    @Override
    void showAll() {
        // TODO Auto-generated method stub
        System.out.println("Բ�ε����Ϊ��"+getArea()+"�ܳ�Ϊ"+getPer());
    }
    public Circle(double r){
        this.radius=r;
    }
   public Circle(String c){
       this.color=c;
       
   }
}

text

package com.shape;

public class text {
    public static void main(String[] args) {
        Rectangle r=new Rectangle(3.0,4.0);
        r.showAll();
        Circle c=new Circle(5.3);
        c.showAll();
    }
}