Xml Handling in Android

In recent years I have mostly coded in C#, so on entering the wonderful world of Android and polishing up my Java skills, I find I sorely miss some of the niftier C# language elements like indexers and properties and their proliferation throughout various .NET frameworks classes.

When it came to querying/modifying XML in Android, I found it handy to write a handful of helper methods which achieve the equivalents of the below in C#:

   XmlElement XmlNode[string name];  (get)
   string XmlNode.InnerText;  (get)
   string XmlNode.InnerText;  (set)
   string XmlNode.OuterText;  (get)

Also, note a solution to the very annoying org.w3c.dom.Node.setNodeValue(String) problem/workaround in setInnertext().

Enjoy:

import java.io.IOException;

import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xmlpull.v1.XmlSerializer;

/**
 * A class containing a collection of helper methods for common Xml node navigation/query
 * 
 * @author Scott Powell
 */
public class XmlUtils
{
    public static Element getChildByName(Element e, String name)
    {
        NodeList l = e.getChildNodes();
        if (l == null || l.getLength() == 0)
            return null;    // not found
        
        for (int i = 0; i < l.getLength(); i++)
        {
            Node n = l.item(i);
            if ((n instanceof Element) && n.getNodeName().equals(name))
                return (Element)n;
        }
        return null;   // not found
    }
    
    public static String getInnerText(Element e)
    {
        NodeList l = e.getChildNodes();
        if (l == null || l.getLength() == 0)
            return "";    /// empty
        
        int idx = 0;
        while (idx < l.getLength())
        {
            if (l.item(idx).getNodeType() == Node.TEXT_NODE)
                return l.item(idx).getNodeValue();
            idx++;
        }
        return "";    // no #text node found, so return empty string
    }
    
    public static void setInnerText(Element e, String val)
    {
        NodeList l = e.getChildNodes();
        if (l != null && l.getLength() > 0)
        {
            int idx = 0;
            while (idx < l.getLength())
            {
                Node n = l.item(idx); 
                if (n.getNodeType() == Node.TEXT_NODE)
                {
                    //n.setNodeValue(val);  //  this isn't changing value!!
                    Node text = e.getOwnerDocument().createTextNode(val);
                    e.replaceChild(text, n);
                    return;
                }
                idx++;
            }
        }
        // no #text Node, so create one
        Node text = e.getOwnerDocument().createTextNode(val);
        e.appendChild(text);
    }
    
    public static void writeElementTo(Element e, XmlSerializer s) throws IOException
    {
        s.startTag("", e.getNodeName());
        if (e.hasAttributes())
        {
            NamedNodeMap m = e.getAttributes();
            for (int i = 0; i < m.getLength(); i++)
            {
                Node n = m.item(i);
                s.attribute("", n.getNodeName(), n.getNodeValue());
            }
        }
        if (e.hasChildNodes())
        {
            NodeList kids = e.getChildNodes();
            for (int i = 0; i < kids.getLength(); i++)
            {
                Node n = kids.item(i);
                if (n.getNodeType() == Node.ELEMENT_NODE)
                    writeElementTo((Element)n, s);  // recursively write child element
                else if (n.getNodeType() == Node.TEXT_NODE)
                {
                    s.text(n.getNodeValue());
                }
            }
        }

        s.endTag("", e.getNodeName());
    }
}