class A
{
  A(){
  new B(this).print();
}
public void print(){
  System.out.println("my name is A,nice to meet you ");
}
}
public class B
{
   A a;
   public B(A a){
   this.a = a;//这里有没有问题？这里的a不是还没有初始化吗？
}
   public  void print(){
   a.print();
   System.out.println("hello,I'am B,nice to meet you too");
}
}