Populating JTree from database

Question

Hi experts,
I need some feedbacks about the way i populate my JTree from database, Is there any better alternatives?
If yes, try explain it in detail.. I'm still new in Java.
Sample database table:
|       node_id      |       name      |       parent       |       hasChild      |
|         1          |     garbage     |        null        |           1         |
|         2          |       item      |          1         |           1         |
|         3          |      mouse      |          2         |           0         |
|         4          |       board     |          2         |           0         |
|         5          |       item2     |          1         |           1         |
|         6          |       item3     |          1         |           1         |
|         7          |       pants     |          5         |           0         |
-----------------------------------------------------------------------------------Here's the sample of my code:
//... ResultSet rs = .....
rs.last();
int rowCount = rs.getRow(); //Get the total number of row in database table
rs.beforeFirst();
int i = 0;
int j = 0;
String [] nodeID = new String[rowCount];  //The node ID
String [] parentID = new String[rowCount];  //A pointer to its parent ID
DefaultMutableTreeNode [] node = new DefaultMutableTreeNode[rowCount]; //The node
while(rs.next()) {
     String name = rs.getString("name");
     Boolean bool = rs.getBoolean("hasChild");
     node[i] = new DefaultMutableTreeNode(name,bool);
     parentID[i] = rs.getString("parent");
     nodeID[i] = rs.getInt("node_id") + "";
        //Set as root node when the pointer is null               
     if(parentID.equals("null")) {
          rootNode = node[i];
     i++;
for(i=0; i<rowCount; i++) {
     for(j=0; j<rowCount; j++) {
          if(parentID[j].equals(nodeID[i]) && node[i] != null) {
               node[i].add(node[j]);
node[i] = null; //Obligates the parent after finish adding the child (to prevent unnecessary loops)
//... tree = new JTree(rootNode);
Thanks for the trouble,
Regards,
David

Answer 1

The execution time are base on the code i post'ed here.
Average over 30times using Vector = 640048 nanosecond to execute.
Vector<String> nodeID = new Vector<String>();
Vector<DefaultMutableTreeNode> node = new Vector<DefaultMutableTreeNode>();
Vector<String> parentID = new Vector<String>();
rs.last();
int rowCount = rs.getRow();
rs.beforeFirst();
k=0;
while(rs.next()) {
     String name = rs.getString("name");
     Boolean hasChild = rs.getBoolean("hasChild");
     node.addElement(new DefaultMutableTreeNode(name,hasChild));
     nodeID.addElement(rs.getInt("node_id")+"");
     parentID.addElement(rs.getString("parent"));
     if(parentID.elementAt(k).equals("null")) {
          rootNode = node.elementAt(k);
     k++;
i=0;
while(i<rowCount) {
     j=0;
     while(j<rowCount) {
          if(parentID.elementAt(j).equals(nodeID.elementAt(i)) && node.elementAt(j) != null) {
               node.elementAt(i).add(node.elementAt(j));
               if(!node.elementAt(i).getAllowsChildren())
                    node.insertElementAt(null,j);
          j++;
     i++;
}Average over 30times using LinkedList = 95623 nanosecond to execute.
//This section will have a class Nodes
LinkedList<Nodes> gather = new LinkedList<Nodes>();
while(rs.next()) {
     node = new DefaultMutableTreeNode(rs.getString("name"),rs.getBoolean("hasChild"));                    
     gather.add(new Nodes(rs.getInt("node_id") + "",node,rs.getString("parent")));
for(Nodes findParent : gather) {                    
     if(findParent.getParentID().equals("null")) {
          findParent.setRoot(findParent.getNode());
          rootNode = findParent.getRoot();
     for(Nodes findChild : gather){
          if(findChild.getParentID().equals(findParent.getNodeID()))
               findParent.getNode().add(findChild.getNode());               
}As for the Array method i used from the previous post, the Average code execution time is x3 larger than the vector i used. So please do not use that method.
Note: 1. The code i post can be improved further. 2. Execution time is based on individual computer.
Well, I think i'll stop here. Anyone who wanted to know which method is more efficient currently, here's the answer.
Hope that it helps anyone who have the problem here =).
Edited by: DavidTW on May 23, 2011 3:14 PM
Improved Version : Using for-each loop ( Effective Java, Second Edition, Joshua Bloch, Pg. 210).