Implementing a tree type structure - how?

Question

I am fairly sufficient programming in Java, however I have never had the need to use (or learn) ways of implementing tree structures; therefore i'll try and explain carefully what i'm trying to achieve.
I need a method of grouping a small number of objects (no more than 20) in a logical way. The objects stored in the tree will be of the same class (the actual objects called 'wordObj' are quite basic, they only have 5 String fields).
The purpose is to represent a sentence of text, where each word is represented as a 'wordObj' object, into "meaningful" clusters.
For example, given the sentence:
"The pyramids were built in the egyptian city of Giza, 3000 years ago".
I want to represent the sentence in the following way:
ROOT (node 1): "Pyramids"
CHILD of ROOT (node 2): "Built"
CHILD of node 2 (node 3): "Giza"
CHILD of node 2 (node 4): "3000 years ago"
I have written an algorithm which extracts the information from the sentence so i'm not asking how to that; basically I need to find a way of creating the above tree structure within a single object. So the tree object can be passed between methods and the information held within it can be searched (I.e. get root node, retrieve child objects... etc) and the objects in the leaf nodes retrieved.
I hope I havent been to vague, any help or urls pointing to a suitable tutorial (which I cannot find) would be appreciated!
Thanks

Answer 1

For your example you might want lists (ordered children). Otherwise you could use it pretty much as-is:
final Node root = new Node("Pyramids");
final Node node2 = new Node("Built");
final Node node3 = new Node("Giza");
final Node node4 = new Node("3000 years ago");
root.getChildren().add(node2);
node2.getChildren().add(node3);
node2.getChildren().add(node4);(Edit)
Just to clarify, you would build the above tree however you want to, but would only need to retain the reference to the "root" node in order to pass it into search methods.
I should also point out that if you're planning to do a lot of this sort of thing and you're not committed to using Java, you should probably consider using LISP for which this sort of problem is pretty much its raison d'etre.
This online text is good: http://gigamonkeys.com/book/ and for learning how to do tree searches the Peter Norvig book is excellent: http://norvig.com/paip.html