調用實際的類方法

Question

//主PROGRAMM的我創建的書的對象，並將其插入到一般的鏈表，但即時通訊無法訪問鏈表中的類書的所有方法

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); 

} 

//鏈表類

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)); 
    } 

//想獲得實際的名稱和在這裏顯示列表方法的書auther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

簡答：你不能。

長答案：當您有Node<AnyType>時，我們所知道的只是該值是AnyType的某個實例。它可能是Book，或者它可能不是。由於這是我們在編譯時無法知道的，因此我們不允許在Book中調用方法，但不能調用AnyType。

如果您的要求是將書籍從列表中拉出，則應使其成爲Node<Book>。