第9次作业--接口及接口回调

一、题目

       利用接口和接口回调，实现简单工厂模式，当输入不同字符，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。

package angle;

public interface shape {
    double getArea();

}

package angle;


public class rectangle implements shape{
    double length;
    double width;
    public rectangle(double length,double width){
        this.length=length;
        this.width=width;
    }
    public double getArea() {
        return length*width;
    }

}

package angle;

public class triangle implements shape{
    double a;
    double b;
    double c;
    public triangle(double a,double b,double c){
        this.a=a;
        this.b=b;
        this.c=c;
    }
    double p=(a+b+c)/2;
    
    public double getArea() {
        return Math.sqrt(p*(p-a)*(p-b)*(p-c));
    }

}

package angle;

public class circular implements shape{
    double r;
    public circular(double r){
        this.r=r;
    }
    public double getArea() {
        return 3.14*r*r;
    }

}

package angle;

import java.util.Scanner;

public class choice {
    
        Scanner reader = new Scanner(System.in);
        shape shape = null;
        public shape choice(char c){
        switch (c) {
        case 'r':
            System.out.println("请输入矩形的长和宽");
            shape=new rectangle(2, 2);
            break;
        case 't':
            System.out.println("请输入三角形的三条边");
            shape = new triangle(4,5,6);
            break;
        case 'c':
            System.out.println("请输入圆的半径");
            shape = new circular(5);
            break;
            }

return shape;
        }
    }
    

package angle;

import java.util.Scanner;

public class Text {

    public static void main(String[] args) {
        System.out.println("请选择需要的图形用图形名称首字母小写来代替");
        Scanner reader=new Scanner(System.in);
        char c = reader.next().charAt(0);
               choice factory = new choice();
               cone cone = new cone(factory.choice(c), reader.nextDouble());//获取底面积，高
                System.out.print(cone.getvolum());
        

    }

}

package angle;

public class cone {
    shape shape;
    double high;
    public cone(shape shape ,double high){
        this.shape=shape;
        this.high=high;
}
    public double getvolum(){
        return high*shape.getArea();
        
    }
    public void changeDi(){
        this.shape=shape;
    }
}