How To - Use the XML Parser

XML (Extensible Markup Language) documents allow developers to represent complex data in a simple manner. Developers can completely define their data in XML because it provides fully customized tags. In XML, there are no predefined or hard-coded tags like there are in HTML documents.

The net.rim.device.api.xml.jaxp.XMLParser API allows developers to leverage XML advantages on the BlackBerry platform. This new BlackBerry JDE 4.0 API allows developers to parse XML content and customize the point of view on BlackBerry devices. The sample provided below uses a static web-based XML document and parses through it to display the tag name with its corresponding data values.

import javax.microedition.io.*; import net.rim.device.api.ui.*; import net.rim.device.api.ui.component.*; import net.rim.device.api.ui.container.*; import net.rim.device.api.system.*; import net.rim.device.api.xml.parsers.*; import org.w3c.dom.*; import org.xml.sax.*; class XML_Parsing_Sample extends UiApplication{ //creating a member variable for the MainScreen MainScreen _screen= new MainScreen(); //string variables to store the values of the XML document String _node,_element; Connection _connectionthread; public static void main(String arg[]){ XML_Parsing_Sample application = new XML_Parsing_Sample(); //create a new instance of the application //and start the application on the event thread application.enterEventDispatcher(); } public XML_Parsing_Sample() { _screen.setTitle("XML Parsing");//setting title _screen.add(new RichTextField("Requesting.....")); _screen.add(new SeparatorField()); pushScreen(_screen); // creating a screen //creating a connection thread to run in the background _connectionthread = new Connection(); _connectionthread.start();//starting the thread operation } public void updateField(String node, String element){ //receiving the parsed node and its value from the thread //and updating it here //so it can be displayed on the screen String title="Title"; _screen.add(new RichTextField(node+" : "+element)); if(node.equals(title)){ screen.add(new SeparatorField()); } } private class Connection extends Thread{ public Connection(){ super(); } public void run(){ // define variables later used for parsing Document doc; StreamConnection conn; try{ //providing the location of the XML file, //your address might be different conn=(StreamConnection)Connector.open ("http://localhost:8000/content/test.xml;deviceside=true"); //next few lines creates variables to open a //stream, parse it, collect XML data and //extract the data which is required. //In this case they are elements, //node and the values of an element DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory. newInstance(); DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder(); docBuilder.isValidating(); doc = docBuilder.parse(conn.openInputStream()); doc.getDocumentElement ().normalize (); NodeList list=doc.getElementsByTagName("*"); _node=new String(); _element = new String(); //get the event lock to avoid IllegelStateException while accessing the UI Object obj = Application.getEventLock(); //this "for" loop is used to parse through the //XML document and extract all elements and their //value, so they can be displayed on the device for (int i=0;i<list.getLength();i++){ synchronized(obj){ Node value=list.item(i). getChildNodes().item(0); _node=list.item(i).getNodeName(); _element=value.getNodeValue(); updateField(_node,_element); } }//end for }//end try //will catch any exception thrown by the XML parser catch (Exception e){ System.out.println(e.toString()); } }//end connection function inside run }// end connection class }//end XML_Parsing_Sample