java實現介面類

要求：定義一個介面，介面中有四個抽象方法。

介面類函數：

<br />public interface jiekou {<br />public double area();<br />public double len();<br />public void area1();<br />public void len1();<br />}<br />

Circle類，實現介面：

public class Circle implements jiekou {<br />double r;<br />double esp =3.1415926;<br />Circle(double a)<br />{<br />r=a;<br />}<br />public double area() {<br />// TODO Auto-generated method stub<br />return esp*r*r;<br />}<br />public void area1() {<br />// TODO Auto-generated method stub<br />System.out.println("Circle area()=3.1415926*r*r");<br />}<br />public double len() {<br />// TODO Auto-generated method stub<br />return 2*esp*r;<br />}<br />public void len1() {<br />// TODO Auto-generated method stub<br />System.out.println("Circle len()=2*3.1415926*r");<br />}<br />}<br />

Rectangle類，實現介面：

public class Rectangle implements jiekou {<br />double h,w;<br /> Rectangle(double a,double b)<br />{<br />h=a;w=b;<br />}<br />public double area() {<br />// TODO Auto-generated method stub<br />return h*w;<br />}<br />public void area1() {<br />// TODO Auto-generated method stub<br />System.out.println("h*w");<br />}<br />public double len() {<br />// TODO Auto-generated method stub<br />return 2*h+2*w;<br />}<br />public void len1() {<br />// TODO Auto-generated method stub<br />System.out.println("2*h+2*w");<br />}</p><p>}<br />

主函數：

public class MAIN {<br />/**<br /> * @param args<br /> */<br />public static void main(String[] args) {<br />// TODO Auto-generated method stub<br />jiekou a=new Circle(10);</p><p>System.out.println(a.area());<br />a.area1();<br />jiekou b= new Rectangle(10,20);<br />System.out.println((int )b.area());<br />b.area1();<br />}<br />}<br />