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

Description

Looks through all child elements of the specified root (recursively) and returns the elements 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

list of Elements in the tree under root that match the specified parameters.

Declaration

public static List<Element> locateElements(Element root,
        String tagName, String keyAttributeName,
        String keyAttributeValue)

Method Source Code

//package com.java2s;
/*/*w ww  .  jav a2 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 java.util.*;

import org.w3c.dom.*;

public class Main {
    /**
     * Looks through all child elements of the specified root (recursively) and
     * returns the elements 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 list of Elements in the tree under root that match the specified
     *         parameters.
     * @throws NullPointerException if any of the arguments is null.
     */
    public static List<Element> locateElements(Element root,
            String tagName, String keyAttributeName,
            String keyAttributeValue) {
        List<Element> result = new ArrayList<Element>();
        NodeList nodes = root.getChildNodes();
        Node node;
        int len = nodes.getLength();
        for (int i = 0; i < len; i++) {
            node = nodes.item(i);
            if (node.getNodeType() != Node.ELEMENT_NODE)
                continue;

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

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

            // look inside.

            List<Element> childs = locateElements((Element) node, tagName,
                    keyAttributeName, keyAttributeValue);

            if (childs != null)
                result.addAll(childs);

        }

        return result;
    }

    /**
     * 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();
    }
}