Java SE (Java Platform, Standard Edition)

HI ,
I am getting difficulty in refreshing the mytree .What is wrong I am unable to find out .
.Here the already I have rootNode and it's three subnode subnode1,subnode2,subnode3 .Now when the user click on its any subnode then the new subtree will be genrated with the help of create subtree class . The class refresh remove all the child node of the subtree .

The some portion of the code of the tree is as

public void valueChanged(TreeSelectionEvent e) {
DefaultMutableTreeNode node = (DefaultMutableTreeNode)allServer.getLastSelectedPathComponent();
if (node == null) return;
Object nodeInfo = node.getUserObject();
//if((0 != (node.getChildCount())) || -1 !=(node.getChildCount()))
//getChildren((DefaultMutableTreeNode )nodeInfo);
//if(false!=getChildren((DefaultMutableTreeNode )nodeInfo).isEmpty())
refreshTree((DefaultMutableTreeNode )nodeInfo);

Vector server=null;
if (nodeInfo.equals("subnode1")) {
str ="a";
server = ServerName(str);
CreateSubTree(node,server,str);
}
else if(nodeInfo.equals("subnode2")) {
str ="b";
server = ServerName(str);
CreateSubTree(node,server,str);
}
else if(nodeInfo.equals("subnode3")) {
str ="c";
server = ServerName(str);
CreateSubTree(node,server,str );
}
else if(DEBUG) { //!= node.isLeaf()) {
// this.st.setVisible(true);
}
}

public void refreshTree(DefaultMutableTreeNode node)
{
DefaultMutableTreeNode rootNode = getRootNode(node);
if(rootNode != null)
System.out.println("The value of the childCount is" +rootNode);
int childCount = rootNode.getChildCount();
System.out.println("The value of the childCount is" +childCount);
if(childCount > 0)
{
rootNode.removeAllChildren();
DefaultTreeModel defaultTreeModel = (DefaultTreeModel)allServer.getModel();
if(defaultTreeModel != null)
{

defaultTreeModel = (DefaultTreeModel)allServer.getModel();

defaultTreeModel.nodeStructureChanged(rootNode);

defaultTreeModel.reload(rootNode);

// this two lines of code helps in expanding the tree when a node is added to the tree
TreePath selectedPath = new TreePath(defaultTreeModel.getPathToRoot(rootNode));
allServer.expandPath(selectedPath);

}
}
}


public DefaultMutableTreeNode getRootNode(DefaultMutableTreeNode node1)
{
DefaultTreeModel defaultTreeModel = (DefaultTreeModel)allServer.getModel();
DefaultMutableTreeNode rootNode = (DefaultMutableTreeNode)defaultTreeModel.getChild((DefaultMutableTreeNode)defaultTreeModel.getRoot(),node1.getLevel());//.getRoot();

return rootNode;
}

public void CreateSubTree(DefaultMutableTreeNode node ,Vector server,String str){

Enumeration en=server.elements();
while(en.hasMoreElements())
{
DefaultMutableTreeNode mynode = new DefaultMutableTreeNode(en.nextElement());
node.add(mynode);
}

}

what is wrong please help

Thanks in advance,
anum