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。

代码：

1、Test.java

 1 /**
 2  * 测试类
 3  * 求体积;
 4  */
 5 package cn.edu.ccut;
 6 
 7 import java.util.Scanner;
 8 public class Test {
 9 
10     public static void main(String[] args) {
12         while(true){
13             System.out.println("柱体底的形状:");
14             Scanner reader = new Scanner(System.in);
15             char c = reader.next().charAt(0);
20             Factory f = new Factory();
21             Cone cone = new Cone(f.get(c) , 6); 
22             System.out.println("体积: "+cone.getV());
23         }
24     }
25 
26 }

2、Factory.java

 1 /**
 2  * 工厂类
 3  * get返回用户所需对象;
 4  */
 5 package cn.edu.ccut;
 6 
 7 public class Factory {
 8     Shape shape = null;
 8 
 9     public Shape get(char c){ 
10         switch(c){
11         case 'j':shape = new Rec(3,5);break;
12         case 's':shape = new Triangle(3,4,5);break;
13         
14         case 't':shape = new Trapezoid(4,5,7);break;
15         case 'y':shape = new Circle(3);break;
16         default:System.out.println("wrong");        
17         }
18         return shape;
19     }
20 }

3、Shape.java

1 /**
2  * 图形接口;
4  */
5 package cn.edu.ccut;
6 
7 public interface  Shape {
8     public double getArea(); 
9 }

4、Rec.java

 1 /**
 2  * 实现了图形接口的矩形类包含两个成员变量并实现了getArea方法;
 3  * 成员变量代表的长和宽;
 5  */
 6 package cn.edu.ccut;
 7 
 8 public class Rec implements Shape {
 9     double a;
10     double b;
10 
11     Rec(double a , double b){
12         this.a = a;
13         this.b = b;
14     }
15     public double getArea(){
16         return (a*b);
17     }
18 }

5、Circle.java

 1 /**
 2  * 实现了图形接口的圆类一个成员变量,两个方法;
 3  * 成员变量r为半径;
 4  * 
 5  */
 6 package cn.edu.ccut;
 7 
 8 public class Circle implements Shape{
 9     double r;
10     
11     public Circle(double r){
12         this.r = r;
13     }
14     public double getArea(){
15         return (Math.PI*r*r);
16     }
17 }

6、Triangle.java

 1 /**
 2  * 三角形类三个成员变量,两个方法;
 3  * 成员变量a,b,c代表三个边;
 4  * 
 5  */
 6 package cn.edu.ccut;
 7 
 8 public class Triangle implements Shape{
 9     double a;
10     double b;
11     double c;
12     
13     public Triangle (double a , double b , double c){
14         this.a = a;
15         this.b = b;
16         this.c = c;
17     }
18     public double getArea(){
19         double p = (a + b + c) / 2;
20         return Math.sqrt(p * (p - a) * (p - b) * (p - c));
21     }
22 }

7、Trapezoid.java

 1 /**
 2  * 梯形类包含三个成员变量,两个方法;
 3  * a,b代表上底和下底,height代表高;
 4  * 
 5  */
 6 package cn.edu.ccut;
 7 
 8 public class Trapezoid implements Shape{
 9     double a;
10     double b;
11     double height;
12     
13     public Trapezoid(double a , double b , double height){
14         this.a = a;
15         this.b = b;
16         this.height = height;        
17     }
18     public double getArea(){
19         return (((a + b) * height) / 2);
20     }
21 }

8、Cone.java

 1 /**
 2  * 柱体类两个成员变量,三个方法;
 3  * shape代表底,height代表高;
 4  * 
 5  */
 6 package cn.edu.ccut;
 7 
 8 public class Cone {
 9     Shape shape;
10     double height;
10  
11     public Cone(Shape shape , double height){
12         this.shape = shape;
13         this.height = height;
14     }
15     public double getV(){
16         return (shape.getArea()*height);
17     }
18     public void setDi(Shape shape){ 
19         this.shape = shape;
20     }
21 }

运行结果：