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。

二、源代码

Shape.java

package a.b;
/*
 * 建一个形状接口，求面积的抽象方法
 */
public interface Shape {
    double getArea();

}

Rectangle.java

package a.b;
/*
 * 求长方形面积
 */
public class Rectangle implements Shape {
    double width;
    double length;
    public Rectangle(double width,double length) {
        this.width=width;
        this.length=length;
    }
    public double getArea() {
        return width*length;
    }

}

Zheng.java

package a.b;
/*
 * 求正方形面积
 */
public class Zheng extends Rectangle {
    public Zheng(double side) {
        super(side,side);
    }
    public Zheng(){
        super(0,0);
    }
    public double getArea() {
        return width*width;
    }

}

Trangle.java

package a.b;
/*
 * 计算三角形面积
 */
public class Trangle implements Shape {
    double a;
    double b;
    double c;
    public Trangle(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));
    }

}

 

Circle.java

package a.b;
/*
 * 求圆面积
 */
public class Circle implements Shape {
    public final static double PI=3.14;
    double r;
    public Circle(double r) {
        this.r=r;
    }

    public double getArea() {
        return r*r*PI;
    }

}

Trapezoid.java

package a.b;
/*
 * 求梯形面积
 */
public class Trapezoid implements Shape {
    double sd;
    double xd;
    double h;
    public Trapezoid(double sd,double xd,double h) {
        this.sd=sd;
        this.xd=xd;
        this.h=h;
    }

    @Override
    public double getArea() {
        return (sd+xd)*h/2;
    }

}

Cone.java

package a.b;
/*
 * 定义一个柱体类利用接口回调求体积
 */
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;     //接口回调
    }
    

}

Factory.java

package a.b;
/*
 * 键一个工厂类
 */
import java.util.*;
public class Factory {
    Shape getShape(char c) {
        Scanner sc = new Scanner(System.in);
        Shape shape = null;
        switch(c) {
        case 'r':
            System.out.println("请输入矩形的长和宽");
            shape = new Rectangle(sc.nextInt(), sc.nextDouble());
            break;
        case 'z':
            System.out.println("请输入正方形的边长");
            shape = new Zheng(sc.nextDouble());
            break;
        case 's':
            System.out.println("输入三角形的边长");
            shape=new Trangle(sc.nextDouble(),sc.nextDouble(),sc.nextDouble());
            break;
        case'c':
            System.out.println("请输入圆形的半径");
            shape=new Circle(sc.nextDouble());
            break;
        case't':
            System.out.println("请输入梯形的上底、下底和高");
            shape=new Trapezoid(sc.nextDouble(),sc.nextDouble(),sc.nextDouble());
            break;
        }
        return shape;
    }

}

Test.java

package a.b;
import java.util.*;
public class Test {

    public static void main(String[] args) {
        while(true) {
        Scanner in=new Scanner(System.in);
        System.out.println("输入要计算的形状和柱体的高：长方形（r） 正方形（z） 三角形（s） 圆形（c） 梯形（t）");
        char c=in.next().charAt(0);
        Factory factory=new Factory();
        Cone cone = new Cone(factory.getShape(c), in.nextDouble());
        
        System.out.println(cone.getVolume());

    }

}
}

三、运行结果