What you have coded is not a LinkedList, at least not one that I recognize. For this assignment, you want to create two classes:
LinkNode
LinkedList
A LinkNode has one member field for the data it contains, and a LinkNode reference to the next LinkNode in the LinkedList. Yes, it's a self referential data structure. A LinkedList just has a special LinkNode reference that refers to the first item in the list.
When you add an item in the LinkedList, you traverse all the LinkNode's until you reach the last one. This LinkNode's next should be null. You then construct a new LinkNode here, set it's value, and add it to the LinkedList.
public class LinkNode {
String data;
LinkNode next;
public LinkNode(String item) {
data = item;
}
}
public class LinkedList {
LinkNode head;
public LinkedList(String item) {
head = new LinkNode(item);
}
public void add(String item) {
//pseudo code: while next isn't null, walk the list
//once you reach the end, create a new LinkNode and add the item to it. Then
//set the last LinkNode's next to this new LinkNode
}
}