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 stub num = 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 stub length = 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(); } }