代码为

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 }

结果为三个；