Android XML Parsing Tutorial

The XML Structure

In this tutorial i’ll will be parsing the following XML file. You can get this xml file by accessing http://api.androidhive.info/pizza/?format=xml

<?xml version="1.0" encoding="UTF-8"?>
<menu>
    <item>
        <id>1</id>
        <name>Margherita</name>
        <cost>155</cost>
        <description>Single cheese topping</description>
    </item>
    <item>
        <id>2</id>
        <name>Double Cheese Margherita</name>
        <cost>225</cost>
        <description>Loaded with Extra Cheese</description>
    </item>
    <item>
        <id>3</id>
        <name>Fresh Veggie</name>
        <cost>110</cost>
        <description>Oninon and Crisp capsicum</description>
    </item>
    <item>
        <id>4</id>
        <name>Peppy Paneer</name>
        <cost>155</cost>
        <description>Paneer, Crisp capsicum and Red pepper</description>
    </item>
    <item>
        <id>5</id>
        <name>Mexican Green Wave</name>
        <cost>445</cost>
        <description>Onion, Crip capsicum, Tomato with mexican herb</description>
    </item>
</menu>

Writing XML Parser Class

In your project create a class file and name it as XMLParser.java. The parser class mainly deals the following operations.

⇒ Getting XML content by making HTTP request
⇒ Parsing XML content and getting DOM element of xml.
⇒ Get each xml child element value by passing element node name.

Getting XML content by making HTTP Request

This function will get XML by making an HTTP Request.

public String getXmlFromUrl(String url) {
		String xml = null;

		try {
			// defaultHttpClient
			DefaultHttpClient httpClient = new DefaultHttpClient();
			HttpPost httpPost = new HttpPost(url);

			HttpResponse httpResponse = httpClient.execute(httpPost);
			HttpEntity httpEntity = httpResponse.getEntity();
			xml = EntityUtils.toString(httpEntity);

		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		} catch (ClientProtocolException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		// return XML
		return xml;
	}

Parsing XML content and getting DOM element

After getting XML content we need to get the DOM element of the XML file. Below function will parse the XML content and will give you DOM element.

public Document getDomElement(String xml){
		Document doc = null;
		DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
		try {

			DocumentBuilder db = dbf.newDocumentBuilder();

			InputSource is = new InputSource();
		        is.setCharacterStream(new StringReader(xml));
		        doc = db.parse(is); 

			} catch (ParserConfigurationException e) {
				Log.e("Error: ", e.getMessage());
				return null;
			} catch (SAXException e) {
				Log.e("Error: ", e.getMessage());
	            return null;
			} catch (IOException e) {
				Log.e("Error: ", e.getMessage());
				return null;
			}
                // return DOM
	        return doc;
	}

Get each xml child element value by passing element node name

public String getValue(Element item, String str) {
	NodeList n = item.getElementsByTagName(str);
	return this.getElementValue(n.item(0));
}

public final String getElementValue( Node elem ) {
	     Node child;
	     if( elem != null){
	         if (elem.hasChildNodes()){
	             for( child = elem.getFirstChild(); child != null; child = child.getNextSibling() ){
	                 if( child.getNodeType() == Node.TEXT_NODE  ){
	                     return child.getNodeValue();
	                 }
	             }
	         }
	     }
	     return "";
  }	

Usage

Following is the code snippet for handling xml operations. I am using xml parser class so far we built and looping through each xml element and getting the child data.

// All static variables
static final String URL = "http://api.androidhive.info/pizza/?format=xml";
// XML node keys
static final String KEY_ITEM = "item"; // parent node
static final String KEY_NAME = "name";
static final String KEY_COST = "cost";
static final String KEY_DESC = "description";

XMLParser parser = new XMLParser();
String xml = parser.getXmlFromUrl(URL); // getting XML
Document doc = parser.getDomElement(xml); // getting DOM element

NodeList nl = doc.getElementsByTagName(KEY_ITEM);

// looping through all item nodes <item>
for (int i = 0; i < nl.getLength(); i++) {
	String name = parser.getValue(e, KEY_NAME); // name child value
	String cost = parser.getValue(e, KEY_COST); // cost child value
	String description = parser.getValue(e, KEY_DESC); // description child value
}

Parsing XML data and updating into ListView

In my previous tutorial Android ListView Tutorial i explained how to create listview and updating with list data. Below i am implementing same listview but the list data i am updating is from parsed xml. This ListView has multiple sub text like name, cost and description.

public class AndroidXMLParsingActivity extends ListActivity {

	// All static variables
	static final String URL = "http://api.androidhive.info/pizza/?format=xml";
	// XML node keys
	static final String KEY_ITEM = "item"; // parent node
	static final String KEY_ID = "id";
	static final String KEY_NAME = "name";
	static final String KEY_COST = "cost";
	static final String KEY_DESC = "description";

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);

		ArrayList<HashMap<String, String>> menuItems = new ArrayList<HashMap<String, String>>();

		XMLParser parser = new XMLParser();
		String xml = parser.getXmlFromUrl(URL); // getting XML
		Document doc = parser.getDomElement(xml); // getting DOM element

		NodeList nl = doc.getElementsByTagName(KEY_ITEM);
		// looping through all item nodes <item>
		for (int i = 0; i < nl.getLength(); i++) {
			// creating new HashMap
			HashMap<String, String> map = new HashMap<String, String>();
			Element e = (Element) nl.item(i);
			// adding each child node to HashMap key => value
			map.put(KEY_ID, parser.getValue(e, KEY_ID));
			map.put(KEY_NAME, parser.getValue(e, KEY_NAME));
			map.put(KEY_COST, "Rs." + parser.getValue(e, KEY_COST));
			map.put(KEY_DESC, parser.getValue(e, KEY_DESC));

			// adding HashList to ArrayList
			menuItems.add(map);
		}

		// Adding menuItems to ListView
		ListAdapter adapter = new SimpleAdapter(this, menuItems,
				R.layout.list_item,
				new String[] { KEY_NAME, KEY_DESC, KEY_COST }, new int[] {
						R.id.name, R.id.desciption, R.id.cost });

		setListAdapter(adapter);

		// selecting single ListView item
		ListView lv = getListView();
                // listening to single listitem click
		lv.setOnItemClickListener(new OnItemClickListener() {

			@Override
			public void onItemClick(AdapterView<?> parent, View view,
					int position, long id) {
				// getting values from selected ListItem
				String name = ((TextView) view.findViewById(R.id.name)).getText().toString();
				String cost = ((TextView) view.findViewById(R.id.cost)).getText().toString();
				String description = ((TextView) view.findViewById(R.id.desciption)).getText().toString();

				// Starting new intent
				Intent in = new Intent(getApplicationContext(), SingleMenuItemActivity.class);
				in.putExtra(KEY_NAME, name);
				in.putExtra(KEY_COST, cost);
				in.putExtra(KEY_DESC, description);
				startActivity(in);

			}
		});
	}
}