How could I know when a class is created?

So I made a simple program that allows you to create instances of a ton of classes. Now I'm responsible to send the instances created to a server. I really like the classes constructors so I really didn't want to alter them. How could I listen to this program so that I could know what classes were recently created, i was thinking in using reflection and maybe threads?

Here a shorter example of what i want to accomplish:

public class MainApplicaton{

     public static void main(String []args){
        ConnectServer.listenToCreatedInstances().
        new Vase();
        new Dog();
        new House();
     }
}

package stuff.components;
public class Human{
    public Human(){

    }
}

package stuff.components;
public class Dog{
    public Dog(){

    }
}

package stuff.components;
public class House{
    public House(){

    }
}

Now my listener thread:

   public enum ConnectServer {
        Server;

        public void listenTocreatedIntances(){
            //Something happens here
            Class c ..
            System.out.println("A instance of "+c.getName());
        }
    }