How applet use external resource?

Question

u can        openFolder = new ImageIcon("button_lit.jpg");
        closedFolder = new ImageIcon("button.jpg");
        leafIcon = new ImageIcon("leaf.gif");        JTree tree = new JTree();
        JScrollPane scrollPane = new JScrollPane(tree);
        DefaultTreeCellRenderer renderer = new DefaultTreeCellRenderer();        renderer.setClosedIcon(closedFolder);
        renderer.setOpenIcon(openFolder);
        renderer.setLeafIcon(leafIcon);        tree.setCellRenderer(renderer);
        tree.setEditable(true);
        getContentPane().add(scrollPane);