Android XML Element Child Get locateElement(Element root, String tagName, String keyAttributeName, String keyAttributeValue)

Description

Looks through all child elements of the specified root (recursively) and returns the first element that corresponds to all parameters.

License

LGPL

Parameter

Parameter	Description
root	the Element where the search should begin
tagName	the name of the node we're looking for
keyAttributeName	the name of an attribute that the node has to have
keyAttributeValue	the value that attribute must have

Exception

Parameter	Description
NullPointerException	if any of the arguments is null.

Return

the Element in the tree under root that matches the specified parameters.

Declaration

public static Element locateElement(Element root, String tagName,
        String keyAttributeName, String keyAttributeValue)

Method Source Code

//package com.java2s;
/*/*  w w w  .  j  av  a 2  s.  c o m*/
 * Jitsi, the OpenSource Java VoIP and Instant Messaging client.
 *
 * Distributable under LGPL license.
 * See terms of license at gnu.org.
 */

import org.w3c.dom.*;

public class Main {
    /**
     * Looks through all child elements of the specified root (recursively)
     * and returns the first element that corresponds to all parameters.
     *
     * @param root the Element where the search should begin
     * @param tagName the name of the node we're looking for
     * @param keyAttributeName the name of an attribute that the node has to
     * have
     * @param keyAttributeValue the value that attribute must have
     * @return the Element in the tree under root that matches the specified
     * parameters.
     * @throws NullPointerException if any of the arguments is null.
     */
    public static Element locateElement(Element root, String tagName,
            String keyAttributeName, String keyAttributeValue) {
        NodeList nodes = root.getChildNodes();
        int len = nodes.getLength();

        for (int i = 0; i < len; i++) {
            Node node = nodes.item(i);

            if (node.getNodeType() != Node.ELEMENT_NODE)
                continue;

            Element element = (Element) node;

            // is this the node we're looking for?
            if (node.getNodeName().equals(tagName)) {
                String attr = element.getAttribute(keyAttributeName);

                if ((attr != null) && attr.equals(keyAttributeValue))
                    return element;
            }

            //look inside.
            Element child = locateElement(element, tagName,
                    keyAttributeName, keyAttributeValue);

            if (child != null)
                return child;
        }
        return null;
    }

    /**
     * Extracts from node the attribute with the specified name.
     * @param node the node whose attribute we'd like to extract.
     * @param name the name of the attribute to extract.
     * @return a String containing the trimmed value of the attribute or null
     * if no such attribute exists
     */
    public static String getAttribute(Node node, String name) {
        if (node == null)
            return null;

        Node attribute = node.getAttributes().getNamedItem(name);
        return (attribute == null) ? null : attribute.getNodeValue().trim();
    }
}