使用类的静态字段和构造函数，可以跟踪某个类所创建对象的个数

 

package TongJi;

public class Duixiang {
    private static int n;
    public Duixiang()
    {
        n++;
    }
    public static int getNum()
    {
        return n;
    }
    public static void main(String[] args) {
        
        Duixiang t1=new Duixiang();
        Duixiang t2=new Duixiang();      
        System.out.println("一共创建了："+Lianxi.getNum()+"个对象");
    }

}