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、源程序
package com.ccut;/**创建接口,创建方法求面积*/ public interface Shape { abstract double getArea(); }
package com.ccut;/**创建一个圆类继承shape接口,定义半径r,PI,圆的构造方法和重写求面积方法*/ public class Circle implements Shape{ double r; final double PI=3.14; Circle(double r){ this.r=r; } public double getArea(){ return r*r*PI; } }
package com.ccut;/**创建一个正方形类继承shape接口,定义边长a,正方形构造方法和重写求面积方法*/ public class Square implements Shape { double a; public double getArea(){ return a*a; } Square(double a){ this.a=a; } }
package com.ccut;/**创建一个梯形类继承shape接口,定义上底a,下底b,高h,梯形构造方法和重写求面积方法*/ public class Trapezoid implements Shape{ double a; double b; double h; Trapezoid(double a,double b,double h){ this.a=a; this.b=b; this.h=h; } public double getArea(){ return (a+b)*h/2; } }
package com.ccut;/**创建一个三角形类继承shape接口,定义三边a,b,c,三角形构造方法和重写求面积方法*/ public class SJX implements Shape{ double a; double b; double c; SJX(double a,double b,double c){ this.a=a; this.b=b; this.c=c; } public double getArea(){ double q = (a + b + c) / 2; return Math.sqrt(q*(q-a)*(q-b)*(q-c)); } }
package com.ccut;/**创建一个柱体类,定义柱体的高h,图形shape,换底方法,求体积方法和构造方法*/ public class Cylinder { double h; Shape shape; public void setShape(Shape shape){ this.shape=shape; } public double getV(){ return h*shape.getArea(); } Cylinder(double h,Shape shape){ this.h=h; this.shape=shape; } }
package com.ccut; import java.util.Scanner; public class GC { Shape shape=null; Scanner reader = new Scanner(System.in);/**创建一个工厂类,创建一个图形对象设为空,引用输入操作提示用户输入字符,利用switch语句给柱体赋底*/ public Shape getShape() { char i=reader.next().charAt(0); switch(i) { case'y':System.out.println("以圆形为底的柱体体积是:");shape=new Circle(5);break; case'z':System.out.println("以正方形为底的柱体体积是:");shape=new Square(6);break; case't':System.out.println("以梯形为底的柱体体积是:");shape=new Trapezoid(4,5,2);break; case'j':System.out.println("以矩形为底的柱体体积是:");shape=new Rectangle(4,5);break; case's':System.out.println("以三角形为底的柱体体积是:");shape=new SJX(4,5,6);break; } return shape; } }
import java.util.*;/**提示用户输入,定义高h,用for循环输出五个图形为底的体积,创建一个工厂类对象,一个柱体类对象,引用换底方法,输出柱体的体积*/ public class Test { public static void main(String[] args) { System.out.println("请输入柱体的高:"); double h; Scanner r=new Scanner(System.in); h=r.nextDouble(); for(int j=0;j<5;j++){ System.out.println("请选择柱体以何图形为底:“y”为圆形,“z”为正方形,“t”为梯形,“j”为矩形“s”为三角形"); GC f=new GC(); Cylinder zt=new Cylinder(h,f.getShape()); zt.setShape(f.shape); System.out.println(zt.getV()); } } }
三、运行结果