Java杂谈之接口和继承的经典案例

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以下是关于接口和的一个经典案例。

包含Shape接口(形状)，Point类(点)，Circle类(圆)，Column类(圆柱)，Test类(测试)

一些注意点和知识在其中的注释中已经说明了，就不额外赘述了。

1.Shape接口：

package JavaInterface;public interface Shape {public abstract double area();public abstract double volume();public abstract String getName();}

2.Point类：

package JavaInterface;public class Point implements Shape {private int x;private int y;public Point() {this.x = 0;this.y = 0;}public Point(int x, int y) {this.x = x;this.y = y;}public int getX() {return x;}public void setX(int x) {this.x = x;}public int getY() {return y;}public void setY(int y) {this.y = y;}@Overridepublic double area() {// TODO Auto-generated method stubreturn 0;}@Overridepublic double volume() {// TODO Auto-generated method stubreturn 0;}@Overridepublic String getName() {// TODO Auto-generated method stubreturn "点：[" + this.x + "," + this.y + "]";}}

3.Circle类：

package JavaInterface;public class Circle extends Point implements Shape {private int r;public Circle() {this.r = 0;}public Circle(int x, int y, int r) {super(x, y);this.r = r;}@Overridepublic double area() {return Math.PI * r*r;}@Overridepublic String getName() {return "圆：半径=" + this.r;}public int getR() {return r;}public void setR(int r) {this.r = r;}}

4.Column类：

package JavaInterface;public class Column extends Circle {private int h;public Column() {this.h = 0;}public Column(int x, int y, int r, int h) {super(x, y, r);this.h = h;}@Overridepublic String getName() {return "圆柱：高度=" + this.h;}@Overridepublic double area() {return super.area() * 2 + 2 * Math.PI * h * super.getR();}@Overridepublic double volume() {return super.area() * h;}}

5.Test类：

package JavaInterface;public class Test {public static void main(String[] args) {//圆//将对象的引用定义为接口，即面向接口的编程Shape sc = new Circle(2,4,8);Circle c = new Circle(2,4,8);System.out.println("类型："+c.getName());System.out.println("面积："+c.area());System.out.println("体积："+c.volume());//圆柱Column col = new Column(2,4,8,2);System.out.println("类型："+col.getName());System.out.println("面积："+col.area());System.out.println("体积："+col.volume());}}

6.结果截图：

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