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。

代码实现：

//*定义一个shape接口用来做柱体的底*//
package cn.edu.ccut.po;
public interface Shape {
    abstract double getArea();
}

//*定义圆形类继承shape接口*//
package cn.edu.ccut.po;
public class Circle implements Shape{
    final double PI=3.14;
    double r;
    Circle(double r){
        this.r=r;
    }
    public double getArea(){
        return PI*r*r;
    }
}

//*定义一个矩形类继承shape结口*//
package cn.edu.ccut.po;
public class Rectangle implements Shape{
    double width;
    double length;
    
    Rectangle(double width,double length){
        this.length=length;
        this.width=width;
    }
    public double getArea(){
        return width*length;
    }
}

//*定义一个正方形类继承shape接口*//
package cn.edu.ccut.po;
public class Square implements Shape {
    double length;
    double area;
    Square(double length){
        this.length=length;
    }
    public double getArea(){
        return area=length*length;
    }
}
 

//*定义一个梯形类继承shape接口*//
package cn.edu.ccut.po;
public class Trapezoid implements Shape{
    double shangdi;
    double xiadi;
    double height;
    
    Trapezoid(double shangdi,double xiadi,double height){
        this.shangdi=shangdi;
        this.xiadi=xiadi;
        this.height=height;
    }
    public double getArea(){
        return(shangdi+xiadi)*height/2;
    }
}

//*定义一个三角形类继承shape接口*//
package cn.edu.ccut.po;
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 p=(a+b+c)/2;
        return Math.sqrt(p*(p-a)*(p-b)*(p-c));
    }
}

//*定义柱体类，定义一个换底方法*//
package cn.edu.ccut.po;
public class Cone {
    Shape shape;
    double high;
    
    public Cone(Shape shape,double high){
        this.shape=shape;
        this.high=high;
    }
    public double getVolume(){
        return shape.getArea()*high;
    }
    public void setShape(Shape shape){
        this.shape=shape;
    }
}

//*创建一个工厂类，并用switch语句选择柱体的底的形状*//
package cn.edu.ccut.po;
import java.util.*;
public class Factory {
    Shape shape=null;
    Scanner input=new Scanner(System.in);
    public Factory(double height){
        Cone cone=new Cone(this.getShape(),height);
        System.out.println(cone.getVolume());
    }
    public Shape getShape(){
        System.out.println("请选择底的图形：矩形:R；正方形:S；圆形:C；三角形:V；梯形:T");
        char A=input.next().charAt(0);
        switch(A){
        case'R':System.out.println("以矩形为底的柱体体积为：");shape=new Rectangle(5,8);break;
        case'S':System.out.println("以正方形为底的柱体体积为：");shape=new Square(6);break;
        case'C':System.out.println("以圆形为底的柱体体积为：");shape=new Circle(2);break;
        case'V':System.out.println("以三角形为底的柱体体积为：");shape=new Triangle(5,3,4);break;
        case'T':System.out.println("以梯形为底的柱体体积为：");shape=new Trapezoid(4,5,9);break;
        }
        return shape;
    }
}

//*测试类*//
package cn.edu.ccut.po;
public class Text {
    public static void main(String[] args) {
        double height=8;
        Factory factory=new Factory(height);
    }

}

运行结果：