How to correctly use the evaluate() method in Xpath?

Question

I have this sample code. I would expect the output to be something like
Channel #0
Channel Name : Ch1
Channel #1
Channel Name : Ch2
Channel #2
Channel Name : Ch3
but all I get is
Channel #0
Channel Name : Ch1
Channel #1
Channel Name : Ch1
Channel #2
Channel Name : Ch1
Do I misuse the evaluate() method? It seems the evaluate method disregards the"doc" start node I pass in and always start from the beginning of the XML...
Very appreciate your suggestion. Thank you very much.
import javax.xml.xpath.*;
import org.xml.sax.InputSource;
import java.io.StringReader;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
public class EvaluateTest {
     * @param args
     public static void main(String[] args) {
          String myxml = "<?xml version='1.0' encoding='utf-8' ?><mytest><ChannelList>" +
          "<Channel><ChannelId>0001</ChannelId><ChannelName>Ch1</ChannelName></Channel>" +
          "<Channel><ChannelId>0002</ChannelId><ChannelName>Ch2</ChannelName></Channel>" +
          "<Channel><ChannelId>0003</ChannelId><ChannelName>Ch3</ChannelName></Channel>" +
          "</ChannelList></mytest>";
          //Get the Document object
          Document doc = null;
          try {
               InputSource inputSource = new InputSource();
               inputSource.setCharacterStream( new StringReader(myxml));
               DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
               DocumentBuilder db = factory.newDocumentBuilder();
               doc = db.parse(inputSource);
               //Iterate thru the Channel list
               NodeList channellist = getSubElements(doc, "/mytest/ChannelList/Channel");
               if (channellist==null)
                    System.out.println("the channel list is null");
               for (int i=0, len=channellist.getLength(); i<len; i++) {
                    System.out.println("Channel #" + i);
                    /*{XPathFactory factory = XPathFactory.newInstance();
                    XPath anxpath = factory.newXPath();
                    String result = (String)anxpath.evaluate(".", channellist.item(i), XPathConstants.STRING);
                    out.println(result);}*/
                    String name = getTagValue(channellist.item(i), "//ChannelName/text()", -1);
                    System.out.println("Channel Name : " + name);
          catch ( Exception e ) {
               e.printStackTrace();
               return;
     //Get the text value of a tag from a document object using XPath method
     static public String getTagValue(Object doc, String xpathstr, int index) throws Exception {
          String result = "";
          if ((doc==null)     || (xpathstr==null) || "".equals(xpathstr))
               return result;
          XPathFactory factory = XPathFactory.newInstance();
          XPath xpath = factory.newXPath();
          result = (String)xpath.evaluate(xpathstr, doc, XPathConstants.STRING);
          if (result==null)
               result = "";
          return result;
     static public NodeList getSubElements(Object doc, String xpathstr) throws Exception {
          if ((doc==null)     || (xpathstr==null) || "".equals(xpathstr))
               return null;
          XPathFactory factory = XPathFactory.newInstance();
          XPath xpath = factory.newXPath();
          Object result = xpath.evaluate(xpathstr, doc, XPathConstants.NODESET);
          return (NodeList)result;
}

Answer 1

Sorry here is a repost of the code. Didn't realize there is a code tag feature.
import javax.xml.xpath.*;
import org.xml.sax.InputSource;
import java.io.StringReader;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
public class EvaluateTest {
    * @param args
   public static void main(String[] args) {
      String myxml = "<?xml version='1.0' encoding='utf-8' ?><mytest><ChannelList>" +
                  "<Channel><ChannelId>0001</ChannelId><ChannelName>Ch1</ChannelName></Channel>" +
                             "<Channel><ChannelId>0002</ChannelId><ChannelName>Ch2</ChannelName></Channel>" +
                  "<Channel><ChannelId>0003</ChannelId><ChannelName>Ch3</ChannelName></Channel>" +
                  "</ChannelList></mytest>";
      //Get the Document object
      Document doc = null;
      try {
            InputSource inputSource = new InputSource();
            inputSource.setCharacterStream( new StringReader(myxml));
            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            DocumentBuilder db = factory.newDocumentBuilder();
            doc = db.parse(inputSource);
            //Iterate thru the Channel list
            NodeList channellist = getSubElements(doc, "/mytest/ChannelList/Channel");
            if (channellist==null)
                  System.out.println("the channel list is null");
            for (int i=0, len=channellist.getLength(); i<len; i++) {
                  System.out.println("Channel #" + i);
                  String name = getTagValue(channellist.item(i), "//ChannelName/text()", -1);
                  System.out.println("Channel Name : " + name);
      } catch ( Exception e ) {
            e.printStackTrace();
            return;
   //Get the text value of a tag from a document object using XPath method
   static public String getTagValue(Object doc, String xpathstr, int index) throws Exception {
      String result = "";
      if ((doc==null)     || (xpathstr==null) || "".equals(xpathstr))
            return result;
      XPathFactory factory = XPathFactory.newInstance();
      XPath xpath = factory.newXPath();
      result = (String)xpath.evaluate(xpathstr, doc, XPathConstants.STRING);
      if (result==null)
            result = "";
      return result;
   static public NodeList getSubElements(Object doc, String xpathstr) throws Exception {
      if ((doc==null)     || (xpathstr==null) || "".equals(xpathstr))
            return null;
      XPathFactory factory = XPathFactory.newInstance();
      XPath xpath = factory.newXPath();
      Object result = xpath.evaluate(xpathstr, doc, XPathConstants.NODESET);
      return (NodeList)result;
}