add() method for a linked list

Question

我正试图创建一个方法，将节点添加到链表中，但到目前为止还没有成功。这是我的会员vars代码：

private Object data; 
private int size = 0;
private Node head = null; 
private Node tail = null;
    public void add(Object item){
    Node temp = head;
    if (head != null) {
        // THIS IS THE PROBLEM SITE
        while(temp.getNext()!=null){
            temp=temp.getNext();
        }
        //set next value equal to item
        Node ab = (Node) item; // It says this is an invalid cast. How do I get around this??
        ab.setNext(ab);
    } 
    else{
        head = new Node(item);
    }
    size++;
}

这里还有我的Node类供参考：

public class Node {
// Member variables.
private Object data; // May be any type you'd like.
private Node next;
public Node(Object obj) {
    this.data = obj; // Record my data!
    this.next = null; // Set next neighbour to be null.
}
// Sets the next neighbouring node equal to nextNode
public void setNext(Node nextNode){
    this.next=nextNode;
}
// Sets the item equal to the parameter specified.
public void setItem(Object newItem){
    this.data = newItem;
}
// Returns a reference to the next node.
public Node getNext(){
    return this.next;
}
// Returns this node ís item.
public Object getItem() {
    return this.data;   
}

谢谢你抽出时间！

Answer 1

如果不想将item强制转换为节点，则需要创建一个新节点并将其中的data设置为item

替换此：

Node ab = (Node) item; // It says this is an invalid cast. How do I get around this??
ab.setNext(ab);

由这样的东西：

Node newNode  = new Node();
newNode.setData(item);
temp.setNext(newNode);