Java学习笔记 --抽象类与接口 基于类Shape

//先写一个抽象类 

import java.awt.print.Printable;public abstract class Polygon {private int num;public Polygon(int a) {// TODO Auto-generated constructor stubnum = a;}public void Printable(){System.out.println("num:"+num);}}

再写一个接口 

public interface Shape {void area();void permitate();}

再写出正方形类去继承抽象类 实现接口

import java.awt.geom.Area;public class Square extends Polygon implements Shape {private double length;public Square(int a) {super(a);// TODO Auto-generated constructor stublength = a;}public void area(){System.out.println("area = " + length*length);}public void permitate(){System.out.println("permitate = "+4*length);}}

最后写一个测试类 作为程序的入口

public class test {public static void main(String args[]){Square a = new Square(3);a.area();a.permitate();}}