INoteItem {
INoteItem(node, parent)
INote node
INoteItem parent
//INoteItem[] children
}

getChildren() {
desArr = node.get..().toArray();
new INoteItem(desArr[i], node)
}
getParent() {
return parent;
}

/*
 * Not only treeview, but also tableview and other listview.
 */
Hierarchy
node+
+-ancestor(node)
+-descendant(node)