LinkedList ToString Output

Question

我正在构建一些测试，只是为了让我自己熟悉链表。

我试图打印出linkedlist对象，但我没有得到任何结果。很可能是我在做一些我不知道的相当基本的错误。

Node.java

public class Node<E> {
    E data;
    Node<E> next;
    //Constructor One
    /** Creates a new node with a null next field.
     * @param dataItem The data stored.
     */
    Node(E dataItem){
        data = dataItem;
        next = null;
    }
    //Constructor Two
    /** Creates a new node that references another node.
     * @param dataItem //the data stored
     * @nodeRef nodRef //The node referenced by new node.
     */
    Node(E dataItem, Node<E> nodeRef){
        data = dataItem;
        next = nodeRef;
    }
}

SlinkedList.java

/** Class to represent a linked list with a link from each node to the next node
 * 
 * @author Study
 *
 * @param <E>
 */
public class SlinkedList<E> {

    // Reference to head Node
    private Node<E> head = null;
    //The number of Items in list
    private int size;
    /** Add an Item to the front of a list.
     * @param item the item to be added*/
    public void addFirst(E item){
        head = new Node<E>(item, head);
        size++;
    }
    /** Add a node after a given node
     * 
     * @param node //The node preceding the new item.
     * @param item //The item to insert.
     */
    public void addAfter(Node<E> node, E item){
        node.next = new Node<E>(item, node.next);
        size++;
    }
    /** Remove the node after a given node
     * @param node, the node before the one to be removed
     * @returns the data from the removed node or null if there is no node to remove.
     */
    //This will work for all nodes except the first one.
    public E removeAfter(Node<E> node){
        Node<E> temp = node.next;
        if(temp != null){
            //Nodes next(node before node to remove) equals temps next(the node after node to remove) 
            node.next = temp.next;
            size--;
            return temp.data;   
        }else{
            return null;
        }
    }
    @Override
    public String toString(){
        Node<E> nodeRef = head;
        StringBuilder result = new StringBuilder();
        while(nodeRef != null){
            result.append(nodeRef.data);
            if(nodeRef.next != null){
                result.append("==>");
            }
            nodeRef = nodeRef.next; // Advance down the list.
        }
        return result.toString();   
    }
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        SlinkedList<String> test = new SlinkedList<String>();
        Node<String> tom = new Node<String>("Tom");
        test.addFirst("AddFirstOne");
        test.addFirst("AddFirstTwo");
        test.toString();
    }
}

我期待从toString()方法中打印出Tom, addfirststone, AddFirstTwo。

在运行时，我只得到一个空的控制台输出。再说一次，我是LinkedLists的新手，我已经做了所有我能想到的正确的输出。

Answer 1

不是打印列表，而是调用返回String的方法。把

test.toString(); // Doesn't print, just returns a String

System.out.println(test); // toString() of test is automatically called