Ugh.. Java Help..

[SaturnX]

Alrite... well here's the deal.. I need to create a "tree" structure, such that I can easily reference all the objects leading to, and from any object in the "tree" Essientially, it will be constructed randomly, (this is my problem, so I can't build the tree downward)

Therefore, I need to build the references out of order, yet be able to add more references from one object to another, essientially at the end leaving me with the following:

[Item] --> [Item2] --> [Item4]
.....|........................|
[Item3]..........[Item5]
.....|.......................|
[Item6]..........[Item7]

(Ignore the periods.. just spacers)

Basically a tree structure, then I need to trace my way back through the structure... being new to Java.. this poses several problems.. as I need to be able to start with say.. item 5, and then continually add more items.. that may not necessarily be in order.
--Mark

 

[Spydermag68]

Try the book: "Java: How to Program, 4th Edition" by Deitel & Deital, page 1117.

 

[MrChad]

Sounds like you need binary tree. Here's the basic code:

public class treeNode{
....public Object data;
....public treeNode leftChild = null;
....public treeNode rightChild = null;

....public treeNode(Object objData){
........data = objData;
....}
}

public class binaryTree{
....treeNode root = null;

....public void addData(Object data){
........if (root == null){
............root = new treeNode(data);
........}
........else{
............addNode(root, data);
........}
....}

....public void addNode(treeNode testNode, Object data){
........if (data < testNode.data){
............if (testNode.leftChild == null){
................testNode.leftChild = new treeNode(data);
............}
............else{
................addNode(testNode.leftChild, data);
............}
........}
........else{
............if (testNode.rightChild == null){
................testNode.rightChild = new treeNode(data);
............}
............else{
................addNode(testNode.rightChild, data);
............}
........}
....}
}

It's fairly easily to build a findNode method (to traverse down the tree). Also, i'm not sure about the syntax and everything, you'll want to double-check. The tree can be fairly off-balanced depending on how the data is entered, which makes traversing it inefficient. A self-balancing (e.g. AVL) tree would be better, but the code is a lot more complex.

 

[Bloodstein]

holy smokes....u put up the binary tree implementation.....who would carry around all these info in their heads?

 

[SaturnX]

Hrmm.. alrite.. thanks a lot.. I'm going to try and fiddle around with the binary tree structures...

--Mark

 

[notfred]

I have code for a self balancing Btree I wrote... want that? 🙂

 

[SaturnX]

Hehe... thanks for the offer notfred... but I think I've found a fairly simple solution... essientially, the problem I need to solve is a path between cities, and the roads link in only certain paths.. I wouldn't be able to interpert Btrees.. and they're really beyond my scope of knowledge at the moment.. but I'll be creating a 2 dimensional boolean array, and work with that.

--Mark *Still Learning Java... But extremely skilled in vb