java - 如何在链表中实现泛型 ？

Question

我一直在尝试创建一个链接列表，该列表使用泛型返回用户选择的数据类型。问题是我的方法 public E get(int sub)无法将我的 return cursor.contents 识别为类型 E generic。

public E get(int sub)
{
    Node cursor = head; //start at the beginning of linked list. 

    for (int c = 1; c <= sub; c++)
    {
        cursor = cursor.next; //move forward by one. 
    }

    return cursor.contents;//return the element that the cursor landed on. 
}


 public class Node <E>
{
        public E contents; 
    @SuppressWarnings("rawtypes")
    public Node next = null; //points to the next node
    //a method has no return type and has the same name as the class
    public Node(E element)
    {
        this.contents = element; 
    }
}

如上所示，contents 参数在 Node 中声明为 type E，但 get 方法不会将 cursor.contents 识别为正确的返回类型。

系统建议我将返回类型更改为 Object，这不是一个选项。或者我将内容更改为已经完成的 E 类型，但它仍然给我一个编译错误。

Answer 1

那是因为你需要把它改成:

public E get(int sub)
{
    Node<E> cursor = head; //you forgot the generics here

    for (int c = 1; c <= sub; c++)
    {
        cursor = cursor.next; 
    }

    return cursor.contents;
}


 public class Node <E>
{
    public E contents; 
    public Node<E> next = null; //you also even suppressed the raw type here

    public Node(E element)
    {
        this.contents = element; 
    }
}