Java SE (Java Platform, Standard Edition)

Hi, I'm currently making messenger application using awt and swing. I've searched in google and here(got this), but till now I haven't got solution.

I want to change user's status icon in the buddy list if the user's status is changed(such like offline and online).

But for now I want to try to change the icon directly by pressing a button first before thinking about listener for the status.

I have this tree

	CustomCellRenderer rosterTreeRenderer = new CustomCellRenderer();
        DefaultMutableTreeNode rosterRoot = new DefaultMutableTreeNode("root");
        DefaultMutableTreeNode rosterGroup = null;

	    rosterGroup = new DefaultMutableTreeNode("group 1");
	    rosterRoot.add(rosterGroup);
	    rosterGroup.add(new DefaultMutableTreeNode("abc"));
	    rosterGroup.add(new DefaultMutableTreeNode("dce"));
	    
	    rosterGroup = new DefaultMutableTreeNode("group 2");
	    rosterRoot.add(rosterGroup);
	    rosterGroup.add(new DefaultMutableTreeNode("zzz"));
	    rosterGroup.add(new DefaultMutableTreeNode("xxx"));
	    rosterGroup.add(new DefaultMutableTreeNode("yyy"));

            rosterTree.setCellRenderer(rosterTreeRenderer);

This is the cell renderer

public class CustomCellRenderer extends DefaultTreeCellRenderer
{
	private static final long serialVersionUID = 1L;

	public CustomCellRenderer(){

	}

        public Component getTreeCellRendererComponent( JTree tree, Object value,
		      boolean isSelected, boolean expanded, boolean leaf, int row,
		      boolean hasFocus )
	{
		DefaultMutableTreeNode node = (DefaultMutableTreeNode)value;
		String	labelText = (String)node.getUserObject();

		if (isSelected)
		{
			System.out.println("selected");
			this.setIcon(UIManager.getIcon("Tree.openIcon"));
			//((DefaultTreeModel) tree.getModel()).nodeChanged(node);
		}
			
		
        else if (leaf) {
            this.setIcon(UIManager.getIcon("Tree.leafIcon"));
          } else if (expanded) {
        	  this.setIcon(null);
          } else {
        	  this.setIcon(null);
          }

		setText(labelText);
		return this;
	}
	
    public Color getBackgroundNonSelectionColor() {
        return(null);
    }

    public Color getBackground() {
        return(null);
    }
}

Whenever I click the user, the user's icon change, the first phase of my testing is working.

But after that I'm confused, how can I change the icon when I click a button at the roster frame. How to invoke and send parameter to change icon of specified user? I already read DefaultTreeCellRenderer javadoc but still haven't found clue to what I wanted, most of the methods noted with "Overridden for performance reasons".

I've already searched for several days for this problem.. Hope someone can help me..

Thanks