<?xml version="1.0" encoding="utf-8"?>
<people>
  <person>
    <name>John Smith</name>
    <age>23</age>
  </person>
</people>

import org.w3c.dom.Element;

Element selectedElement =
       get_selected_element_from_jTree_where_XML_file_located_as_tree_form();

String[] names_of_tag_of_sub_elements_can_be_located_under =
       get_those_name_using_schema_file(selectedElement, schema);