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。

/**  创建了一个图形接口 shape ，抽象方法getArea() ,

      创建矩形类Rectangle、正方形类Square、圆形类Cricle、三角形类Triangle、梯形类Trapezoid 调用接口，

      创建一个柱体类 Cone ，包含一个换底方法和一个求体积的方法 getVolume() ，

      创建一个工厂类Factory，利用switch语句选择柱体的底，数据回调给接口Shape，

      创建主类 Test ，由用户输入图形字符，输入以相应图形为底的柱体体积 。   */

图形接口 shape：

public interface Shape {
    double getArea();
}

矩形类Rectangle：

public class Rectangle implements Shape {
    protected double length;
    protected double width;
    public Rectangle(double length,double width) {
        this.length=length;
        this.width=width;
    }
    Rectangle() {
        // TODO Auto-generated constructor stub
    }

    public double getArea() {
        // TODO Auto-generated method stub
        return length*width;
    }
    
}

正方形类Square：

public class Square implements Shape {
    double side;
    Square(double side){
        this.side=side;
    }
    public double getArea() {
        return side*side;
    }
}

圆形类Cricle：

public class Cricle implements Shape{
    double r;
    final double PI=3.14;
    public Cricle(double r) {
        this.r=r;
    }
    public double getArea() {
        return PI*r*r;
    }
    
}

三角形类Triangle：

public class Triangle implements Shape{
    double tr1;
    double tr2;
    double tr3;
    public Triangle(double tr1,double tr2,double tr3) {
        this.tr1=tr1;
        this.tr2=tr2;
        this.tr3=tr3;
    }
    public double getArea() {
        double p=(tr1+tr2+tr3)/2;
        return Math.sqrt(p*(p-tr1)*(p-tr2)*(p-tr3));
    }
    
}

梯形类Trapezoid：

public class Trapezoid implements Shape {
    double a;
    double b;
    double c;
    public Trapezoid(double a,double b,double c) {
        this.a=a;
        this.b=b;
        this.c=c;
    }

    public double getArea() {
        return (a+b)*c/2;
    }
    
}

柱体类 Cone：

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;
    }
}

工厂类Factory：

import java.util.Scanner;

public class Factory {
    Shape shape = null;
    Scanner sc=new Scanner(System.in);
    Shape getShape(char c) {
        switch (c) {
        case 'j':System.out.print("请依次输入矩形的长和宽：\n");
        double length=sc.nextDouble();
        double width=sc.nextDouble();
        shape=new Rectangle(length,width);
        break;
        case 'z':System.out.print("请输入正方形的边长：\n");
        double side=sc.nextDouble();
        shape=new Square(side);
        break;
        case 'y':System.out.print("请输入圆形的半径：\n");
        double r=sc.nextDouble();
        shape=new Cricle(r);
        break;
        case 's':System.out.print("请输入三角形的三边长：\n");
        double tr1=sc.nextDouble();
        double tr2=sc.nextDouble();
        double tr3=sc.nextDouble();
        shape=new Triangle(tr1, tr2, tr3);
        break;
        case 't':System.out.print("请依次输入梯形的上底，下底，高：\n");
        double a=sc.nextDouble();
        double b=sc.nextDouble();
        double h=sc.nextDouble();
        shape=new Trapezoid(a, b, h);
        break;
        }
        return shape;
    }
}

主类 Test：

import java.util.Scanner;

public class Test {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Factory f=new Factory();
        System.out.print("矩形：j；正方形：z；圆形：y；三角形：s；梯形：t"+"\n"+"请输入图形字符：\n");
        Scanner sc=new Scanner(System.in);
        while(true) {
            char c=sc.next().charAt(0);
            if(c!='j'&&c!='z'&&c!='y'&&c!='s'&&c!='t') {
                System.out.print("输入错误，请重新输入\n");
            }
            else {
                System.out.print("请输入柱体的高：");
                double h=sc.nextDouble();
                Cone cone=new Cone(f.getShape(c),h);
                System.out.print("体积为："+cone.getVolume());
            }
        }
    }

}

运行截图：