Thank you for your ideas and sharing code samples. Sorry If I was unclear in my description. Here is some code to put my problem in perspective:
private static class Folder { // a Folder, has a Name, zero or many child Folders, zero or many Files private final String name; private final List<Folder> folders = new ArrayList<Folder>(); private final List<File> files = new ArrayList<File>(); } now in : getNodeInfo method if (value instanceof Folder) { // if Node is of Type Folder ListDataProvider<Folder> dataProvider = new ListDataProvider<Folder>(((Folder)value).getFolders()); // [***] read below for comments on this Cell<Folder> cell = new AbstractCell<Folder>(){ @Override public void render(Folder value, Object key, SafeHtmlBuilder sb) { if(value!=null){ sb.appendEscaped(value.getName()); } } }; return new DefaultNodeInfo<Folder>(dataProvider, cell); } [***] look carefully at DataProvider here: when Node is of type Folder: I fetch its "Child Folders" with the code below: ListDataProvider<Folder> dataProvider = new ListDataProvider<Folder>(((Folder)value).getFolders()); but when Node is type Folder, I also need to fetch its "Files" ListDataProvider<File> dataProvider = new ListDataProvider<File>(((Folder)value).getFiles()); but with return new DefaultNodeInfo<Folder>(dataProvider, cell); I can only return either Child Folders, or Files, not buth return new DefaultNodeInfo<Folder>(dataProvider, cell); or return new DefaultNodeInfo<File>(dataProvider, cell); I want to return BOTH, because each Folder, contains FOLDERS and FILES, FolderX FolderY FileY1 FileY2 FolderQ FolderT FileW FileZ basically Folder X, contains several child Folders: FolderY, FolderQ, Folder T in addition, also contains FileW and FileZ. for Node Type "Folder", I can only return "one" type, either "Folders" OR "Files". I want to return FOLDERS_AND_FILES. -- You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To post to this group, send email to google-web-tool...@googlegroups.com. To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.