通过构造函数检查生成对象个数

 1 package CheckObjectNumber;
 2 
 3 public class CheckObjectNumber {
 4     private static int num=0;//定义一个静态成员num ，用于检测执行构造函数的次数
 5     public CheckObjectNumber()
 6     {
 7         num++;
 8     }
 9     public static int getNum()
10     {
11         return num;
12     }
13     
14     public static void main(String[] args) {
15         CheckObjectNumber c1=new CheckObjectNumber();
16         CheckObjectNumber c2=new CheckObjectNumber();
17         CheckObjectNumber c3=new CheckObjectNumber();
18         System.out.println("已建对象为："+CheckObjectNumber.getNum()+"个");
19     }
20 
21 }