I, entitled
Callback interface and its use, simple factory mode, when the input different characters,
When representing the respective pattern obtained by using the graphical object factory class, then the figure is calculated in the column bottom volume.
Second, the code segment
(1) shape class
Package ZCY;
public interface the Shape {
public Double the getArea (); // define interfaces mensuration method
}
(2) Rectangle class
package zcy;
//定义矩形类，调用shape接口
public class Rectangle implements Shape{
public double length;
public double width;
public Rectangle(double length,double width){
this.length=length;
this.width=width;
}
public double getArea(){
return width*length;
}
}
(3) Triangle class
package zcy;
//定义三角形类调用Shape接口
public class Triangle implements Shape{
double a,b,c;
public Triangle(double a,double b,double c){
this.a=a;
this.b=b;
this.c=c;
}
public double getArea() {
double m=(a+b+c)/2;
return Math.sqrt(m*(m-a)*(m-b)*(m-c));
}
(4) TiXing class
package zcy;
//定义梯形类，调用shape接口
public class TiXing implements Shape {
double a;
double b;
double h;
public TiXing(double a,double b,double h){
this.a=a;
this.b=b;
this.h=h;
}
public double getArea(){
return (a+b)*h/2;
}
}
（5）Square类
package zcy;
//定义正方形类继承矩形类
public class Square implements Shape{
double a;
public Square(double a){
this.a=a;
}
public double getArea(){
return a*a;
}
}
（6）Circle类
package zcy;
//定义圆形类，调用shape接口
public class Circle implements Shape{
double r;
public Circle(double r){
this.r=r;
}
public double getArea(){
return 3.14*r*r;
}
}
（7）Column类
package zcy;
//定义柱体类，柱体高，换底方法
public class Column {
Shape shape;
double height;
public Column(Shape shape,double height){
this.shape=shape;
this.height=height;
}
public double getVolumn(){
return shape.getArea()*height;
}
public void changeShape(Shape shape){
this.shape=shape;
}
}
（8）Factory类
package zcy;
import java.util.Scanner;
//工厂类 实现通过输入字符，自动创建对应类型的对象
public class Factory {
Shape shape=null;
Scanner reader = new Scanner(System.in);
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 TiXing(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 Triangle(4,5,6);break;
}
return shape;
}
}
（9）Test类
package zcy;
import java.util.Scanner;
public class Test {
/**
* @param args
*/
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");
Factory f=new Factory();
Column col=new Column(f.getShape(),h);
col.changeShape(f.shape);
System.out.println(col.getVolumn());
}
}
}
三、结果运行图
