第9次作业--接口及接口回调

题目：

       利用接口和接口回调，实现简单工厂模式，当输入不同的字符，代表相应图形时，利用工厂类获得图形对象，再计算以该图形为底的柱体体积。

代码及注释：

package com.ccut.java;

/**
 * 接口，一个抽象方法
 * 
 *
 */
public interface Shape {
    abstract double getArea();
}

package com.ccut.java;
/**
 * 圆类继承shape接口
 * @author Administrator
 *
 */
public class Circle implements Shape {
    final double PAI=3.14;
    double r;
    Circle(double r){
        this.r=r;
    }
    public double getArea() {
        return PAI*r*r;
    }

}

package com.ccut.java;

/**
 * 梯形类，继承自Shape接口
 * 
 * @author Administrator
 *
 */
public class Ladder implements Shape {

    double upper_base;
    double under_base;
    double height;

    Ladder(double upper_base, double under_base, double height) {
        this.upper_base = upper_base;
        this.under_base = under_base;
        this.height = height;
    }

    public double getArea() {
        return (upper_base + under_base) * height / 2;
    }
}

package com.ccut.java;
/**
 * 矩形类 继承接口，求面积，以及构造方法
 * @author Administrator
 *
 */
public class Rectangle implements Shape {
    double length;
    double width;
    Rectangle(double length,double width){
        this.length=length;
        this.width=width;
    }

        public double getArea(){
        
            return length*width;
        }
}

package com.ccut.java;
/**
 * 正方形类继承Shape接口
 *
 */
public class Square implements Shape {

    double length;
    double area;

    Square(double length) {
        this.length = length;
    }

    public double getArea() {

        return area = length * length;
    }
}

package com.ccut.java;
/**
 * 三角形类 继承自Shape接口
 * @author Administrator
 *
 */
public class Triangle implements Shape {

    double a;
    double b;
    double c;

    Triangle(double a, double b, double c) {
        this.a = a;
        this.b = b;
        this.c = c;
    }

    public double getArea() {
        double d = (a + b + c) / 2;
        return Math.sqrt(d * (d - a) * (d - b) * (d - c));
    }
}

package com.ccut.java;
/**
 * 柱体类，一个换底方法
 * @author Administrator
 *
 */
public class Podetium{


Shape shape;
double height;
Podetium(Shape shape,double height){
    this.shape=shape;
    this.height=height;
}
void changeBase(Shape shape) {
    this.shape=shape;
}
double getVolume(){
    return shape.getArea()*height;
}
}

package com.ccut.java;

import java.util.Scanner;
/**
 * 工厂类，将计算工厂包装起来
 *
 */
public class Factory {
    Shape shape=null;
    Scanner reader = new Scanner(System.in);
    
    public Factory(double height) {
        Podetium podetium=new Podetium(this.getShape(),height);
        System.out.println(podetium.getVolume());
    }
public Shape getShape() {
    System.out.println("请选择所求柱体的底：（j（矩形）z（正方形）y（圆形）s（三角形）t（梯形）");
    char S=reader.next().charAt(0);
        switch(S) {
        case'j':System.out.println("矩形柱体的体积是：");shape=new Rectangle(2,3);break;
        case'z':System.out.println("正方形柱体的体积是：");shape=new Square(7);break;
        case'y':System.out.println("圆形柱体的体积是：");shape=new Circle(7);break;
        case's':System.out.println("三角形柱体的体积是：");shape=new Triangle(2,3,4);break;
        case't':System.out.println("梯形柱体的体积是：");shape=new Ladder(2,3,4);break;
        }
        return shape;
}
}

package com.ccut.java;

/**
 * 测试类
 *
 */
public class Test {
    public static void main(String[] args) {
        double height = 6;
        Factory factory = new Factory(height);
    }
}

测试运行：