class A{
public A(){
new B(this).print();
}
public void print(){
System.out.println("Hello from A");
}
}
class B{
A a; //????
public B(A a){ //????
this.a=a;
}
public void print(){
a.print();
System.out.println("Hello from B");
}
}
public class ThisUse{
public static void main(String[] args){
new A(); //????
}
}
请具体解释一下程序,谢谢