从通用模板类型Object调用实际的类方法

Question

//程序的主要部分，我创建了一个book对象，并将其插入到通用链接列表中，但是无法访问linklist类中book的所有方法

 public static void main(String[] args) {
 LinkedList<Book> list;
    list = new LinkedList<>();
   Book a=new Book();
   a.setAuthur("ahsan");
   a.setName("DSA");
   a.setNoOfPages(12);


   list.insertFirst(a);

}

//链接列表类

import java.util.NoSuchElementException;


public class LinkedList<AnyType> {
public class Node<AnyType>
{
private AnyType data;
private Node<AnyType> next;
public Node(AnyType data, Node<AnyType> next)
{
this.data = data;
this.next = next;
}

/**
 * @return the data
 */
public AnyType getData() {
    return data;
}

/**
 * @param data the data to set
 */
public void setData(AnyType data) {
    this.data = data;
}

/**
 * @return the next
 */
public Node<AnyType> getNext() {
    return next;
}

/**
 * @param next the next to set
 */
public void setNext(Node<AnyType> next) {
    this.next = next;
}


}

 private Node<AnyType> head;

/*
*  Constructs an empty list
*/
public LinkedList()
{
head = null;
}




 public boolean isEmpty()
 {
   return head == null;
 }
 /*
 *  Inserts a new node at the beginning of this list.
 *  @param item to be inserted in First
 */
  public void insertFirst(AnyType item)
  {
  head = new Node<AnyType>(item, head);
  }
  /*
  *  Returns the first element in the list.
  *  @return First element in linked List
  */
  public AnyType getFirst()
  {
  if(head == null) throw new NoSuchElementException();
  return head.getData();
  }
/*
 *  Removes the first element in the list.
 *  @return Deleted First Item
 */
  public AnyType deleteFirst()
  {
    AnyType tmp = getFirst();
    head = head.getNext();
    return tmp;
  }
 /*
  *  Recursively inserts a new node to the end of this list.
  *  @param item to be inserted in last
  */
  public void insertLast(AnyType item)
  { 
       if( head == null)
        insertFirst(item);
       else
        insertLast(head, item);
  }
  private void insertLast(Node<AnyType> node, AnyType item)
  {
    if(node.getNext() != null) insertLast(node.getNext(), item);
    else
    node.setNext( new Node<AnyType>(item, null));
  }

//想要在显示列表方法中在此处获取书籍的实际名称和作者姓名

  /*
  *   Display all the elements in linked list
  */
  public void DisplayList()
  {
    Node<AnyType> Current=head;
    while(Current!=null)
    {
        System.out.print("[ "+ Current.getData()+" ] -> ");//want to     print name of the book here
       //i do the following but not worked Current.getData().getName();
        Current=Current.getNext();
    }
    System.out.println("NULL");
  }

}

Answer 1

简短的答案：您不能。

长答案：当您拥有Node<AnyType> ，我们所知道的就是该值是AnyType某个实例。 它可能是Book ，也可能不是。 由于这是我们在编译时不知道的事情，因此我们不能允许调用Book方法，而不能AnyType 。

如果您的要求是将书从清单中取出，则应将其设为Node<Book> 。