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。

Shape.java

package com;
//接口
public interface Shape {
    double getArea();

}

Rectangle.java

package com;

public class Rectangle implements Shape {
    double a;//矩形長
    double b;//矩形寬

    public Rectangle(double a, double b) {
        this.a = a;
        this.b = b;
    }

    @Override
    public double getArea() {

        return a * b;//返回面積
    }

}

Squera.java

package com;

public class Squera extends Rectangle {
    public Squera(double a) {//正方形的邊
        super(a, a);

    }

    public double getArea() {
        return a * a;
    }

}

package com;

public class Triangle implements Shape {

    double a;//三角形三邊長
    double b;
    double c;

    public 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));//三角形面積
    }

}

Cricle.java

package com;

public class Cricle implements Shape {

    double r;//半径
    double PI = 3.14;

    public Cricle(double r) {
        this.r = r;
    }

    public double getArea() {

        return r * r * PI;//
    }

}

Trapezoid.java

package com;

public class Trapezoid implements Shape {

    double a;//梯形的两边及高
    double b;//
    double h;//
    public Trapezoid(double a,double b,double h) {
        this.a=a;
        this.b=b;
        this.h=h;
        // TODO Auto-generated constructor stub
    }
    public double getArea() {
        
        return (a+b)*h/2;//梯形面积
    }

}

Cone.java

package com;

public class Cone {
    Shape shape;//定義接口變量
    double h;//高

    public Cone(Shape shape, double h) {
        this.shape = shape;
        this.h = h;

    }

    public double getV() {//球體積
        return shape.getArea() * h;
    }

    public void changeD() {//換底
        this.shape = shape;
    }
}

Factory.java

package com;

import java.util.Scanner;

public class Factory {

    Shape getShape(char c) {
        Scanner reader = new Scanner(System.in);
        Shape shape = null;
        switch (c) {//根据字符判断形状
        case 'R':
            System.out.println("请输入矩形的长和宽
");
            shape = new Rectangle(reader.nextInt(), reader.nextDouble());
            break;
        case 'Z':
            System.out.println("请输入正方形的边长，柱体的高
");
            shape = new Squera(reader.nextDouble());
            break;
        case 'C':
            System.out.println("请输入圆的半径
");
            shape = new Cricle(reader.nextDouble());
            break;
        case 't':
            System.out.println("请输入三角形的三条边
");
            shape = new Triangle(reader.nextDouble(), reader.nextDouble(),
                    reader.nextDouble());
            break;

        case 'T':
            System.out.println("请输入梯形的上底下底和高
");
            shape = new Trapezoid(reader.nextDouble(), reader.nextDouble(),
                    reader.nextDouble());
            break;

        }
        return shape;//
    }
}

Test.java

package com;

import java.util.Scanner;

public class Test {
    public static void main(String[] args) {

        Scanner reader = new Scanner(System.in);
        System.out.print("请输入你选择的形状:矩形R,正方形Z,三角形t,圆C,梯形T:
");
        char c = reader.next().charAt(0);
        Factory factory = new Factory();
        Cone cone = new Cone(factory.getShape(c), reader.nextDouble());//获取底面积，高
        System.out.print(cone.getV());

    }
}