Class X{
Y b =new Y();
X(){
System.out.println(“X”);
}
}
Class Y{
Y(){
System.out.println(“Y”);
}
}
public class Z extends X{
Y y= new Y();
Z(){
System.out.println(“Z”);
}
public static void main(String[] args){
new Z();
}
}
class X{ Y b =new Y(); X(){ super();//指向object根类 System.out.println("X"); } } class Y{ Y(){ super(); //指向object根类 System.out.println("Y"); } } public class Z extends X{ Y y= new Y(); Z(){ super();//指向X类的无参构造 System.out.println("Z"); } public static void main(String[] args){ new Z(); } }