package packtwo; import packtwo.Person; import packtwo.Student; import packtwo.Teacher; public class List {   class Node{  public Object data;  Node next;  public Node()  {     }  public Node(Person data)  {   this.data=data;   this.next=null;  }  public Node(Student data)  {   this.data=data;   this.next=null;  }  public Node(Teacher data)  {   this.data=data;   this.next=null;  } } Node first=null; public List() {  this.first=null; }

void cteatLinklist() {    Person person=new Person("张三",12310000);  Node node1=new Node(person);  Student student=new Student("李四",12320000,89,93,94);  Node node2=new Node(student);  Teacher teacher=new Teacher("王五",12330000,3000);  Node node3=new Node(teacher);  first=node1;  node1.next=node2;  node2.next=node3;  

----------person有自己写的toStr();

?????????为啥person可以调用自己的toStr();可是node1.data.toStr();就是错的？？？

----- 

这是自己写的，输出函数，person的实例方法public void toStr()
 {
  System.out.println( "姓名 "+name+"\n"+"身份证号 "+IDnum);
 }-----------------

    }

   public static void main(String[] args) {   // TODO Auto-generated method stub     List list=new List();  list.cteatLinklist();     }

}