java编程关于接口的程序？

Question

java编程关于接口的程序

Answer 1

package com.shape; public interface Volume {         double PI = 3.1415926;         //计算体积    public double calVolume();         //计算表面积    public double calArea(); }package com.shape; //圆柱体public class Cylinder implements Volume {         private double Radius ;    private double Height;         public Cylinder(double Radius, double Height) {                 this.Radius = Radius;        this.Height = Height;    }     public double getRadius() {        return Radius;    }         public void setRadius(double radius) {        Radius = radius;    }     public double getHeight() {        return Height;    }     public void setHeight(double height) {        Height = height;    }         @Override    public double calVolume() {        // TODO Auto-generated method stub        return PI * Radius * Radius * Height;    }     @Override    public double calArea() {        // TODO Auto-generated method stub        return PI * Radius * Radius * 2 + PI * Radius * Height * 2;    } }package com.shape; //圆锥public class Cone implements Volume {     private double Radius;    private double Height;     public double getRadius() {        return Radius;    }    public void setRadius(double radius) {        Radius = radius;    }    public double getHeight() {        return Height;    }    public void setHeight(double height) {        Height = height;    }     public Cone(double Radius, double Height) {        this.Radius = Radius;        this.Height = Height;    }     //圆锥体的母线的长    public double getConeLine() {         double Line = Radius * Radius + Height * Height;        return Math.sqrt(Line);    }     @Override    public double calVolume() {        // TODO Auto-generated method stub        return PI * Radius * Radius * Height / 3;    }     @Override    public double calArea() {        // TODO Auto-generated method stub        return  PI * Radius * Radius + PI * Radius * getConeLine();    } }public class ShapeTestDemo {     public static void main(String[] args) {        // TODO Auto-generated method stub                 Cylinder cy = new Cylinder(3, 4);        System.out.println(cy.calVolume());        System.out.println(cy.calArea());                 Cone cone = new Cone(3, 4);        System.out.println(cone.calVolume());        System.out.println(cone.getConeLine());        System.out.println(cone.calArea());     } }

Answer 2

package temp; public class VolumeTestDemo {     public static void main(String[] args) {        // TODO Auto-generated method stub             }         interface Volume{        final double pai = 3.1415;        //体积计算        public double calVolume();    }         //圆柱体类    class Cylinder implements Volume{                 //底边半径        double r =0;        //高        double h =0;                 public Cylinder(double r,double h){            this.r = r;            this.h = h;        }         //圆柱体体积计算        @Override        public double calVolume() {            // TODO Auto-generated method stub            return r*r*pai*h;        }             }     //圆锥类    class Cone implements Volume{                 //底边半径        double r =0;        //高        double h =0;                 public Cone(double r,double h){            this.r = r;            this.h = h;        }                 @Override        public double calVolume() {            // TODO Auto-generated method stub            return 1/3*pai*r*r*h;        }             }}

Answer 3

public class Test {    public static void main(String[] args) throws Exception{        Lamp lamp = new Lamp(new RedBulb());        lamp.on();        lamp.setB(new GreenBulb());        lamp.on();    }}class Lamp{    private Bulb b;    public Lamp(Bulb b){        this.b = b;    }    public void on(){        b.light();    }    public void setB(Bulb b){        this.b = b;    }}interface Bulb{    void light();}class RedBulb implements Bulb{    @Override    public void light() {        System.out.println("Red light.");    }}class GreenBulb implements Bulb{    @Override    public void light() {        System.out.println("Green light.");    }}