问如何确定foreach循环中的第一个和最后一个迭代？

package ecb.sdw.pretty;

import org.apache.xml.serialize.OutputFormat;

import org.apache.xml.serialize.XMLSerializer;

import org.w3c.dom.Document;

import org.xml.sax.InputSource;

import org.xml.sax.SAXException;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.ParserConfigurationException;

import java.io.IOException;

import java.io.StringReader;

import java.io.StringWriter;

import java.io.Writer;

/**

 * Pretty-prints xml, supplied as a string.

 * <p/>

 * eg.

 * <code>

 * String formattedXml = new XmlFormatter().format("<tag><nested>hello</nested></tag>");

 * </code>

 */

public class XmlFormatter {

    public XmlFormatter() {

    }

    public String format(String unformattedXml) {

        try {

            final Document document = parseXmlFile(unformattedXml);

            OutputFormat format = new OutputFormat(document);

            format.setLineWidth(65);

            format.setIndenting(true);

            format.setIndent(2);

            Writer out = new StringWriter();

            XMLSerializer serializer = new XMLSerializer(out, format);

            serializer.serialize(document);

            return out.toString();

        } catch (IOException e) {

            throw new RuntimeException(e);

        }

    }

    private Document parseXmlFile(String in) {

        try {

            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

            DocumentBuilder db = dbf.newDocumentBuilder();

            InputSource is = new InputSource(new StringReader(in));

            return db.parse(is);

        } catch (ParserConfigurationException e) {

            throw new RuntimeException(e);

        } catch (SAXException e) {

            throw new RuntimeException(e);

        } catch (IOException e) {

            throw new RuntimeException(e);

        }

    }

    public static void main(String[] args) {

        String unformattedXml =

                "<?xml version=\"1.0\" encoding=\"UTF-8\"?><QueryMessage\n" +

                        "        xmlns=\"http://www.SDMX.org/resources/SDMXML/schemas/v2_0/message\"\n" +

                        "        xmlns:query=\"http://www.SDMX.org/resources/SDMXML/schemas/v2_0/query\">\n" +

                        "    <Query>\n" +

                        "        <query:CategorySchemeWhere>\n" +

                        "   \t\t\t\t\t         <query:AgencyID>ECB\n\n\n\n</query:AgencyID>\n" +

                        "        </query:CategorySchemeWhere>\n" +

                        "    </Query>\n\n\n\n\n" +

                        "</QueryMessage>";

        System.out.println(new XmlFormatter().format(unformattedXml));

    }

}

Transformer transformer = TransformerFactory.newInstance().newTransformer();

transformer.setOutputProperty(OutputKeys.INDENT, "yes");

transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");

//initialize StreamResult with File object to save to file

StreamResult result = new StreamResult(new StringWriter());

DOMSource source = new DOMSource(doc);

transformer.transform(source, result);

String xmlString = result.getWriter().toString();

System.out.println(xmlString);