How to parse XML in Android

Today i am going to discuss about parsing XML in android using DOM parser. Also i am demonstrating how to update ListView with parsed XML data.

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);               }         });     } }

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How to implement list view in Android application

In this tutorial i will be demonstrating how to build simple android ListView. This article is about creating listview and launching new activity on selecting single list item.

Below is screenshot of final output

Let’s get start by creating a project in Eclipse IDE.

1. Create a new project by going to File ⇒ New Android Project. Fill all the details and name your activity as AndroidListViewActivity.
2. Once the project is created open your main activity java file (in this case AndroidListViewActivity.java) and extend the class from ListActivity.

 

public class AndroidListViewActivity extends ListActivity { 3. Now we need a string resources file to store all list item labels. So create an XML file under values folder and name it as list_data.xml and paste the following code. ( Right Click on res/values ⇒ New ⇒ Android XML File) list_data.xml

    
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4. In ListView each list item will be an xml layout, so we can customize each list item. Create an XML file under res/layout folder and name it as list_item.xml and type the following code. This xml layout will be single list item row. ( Right Click on res/layout ⇒ New ⇒ Android XML File)

5. Now open your main activity java file (AndroidListViewActivity.java) and type the following code. In the following code i am importing all xml resources data and storing them in an Array. On the next step i am binding array to ListAdapter. AndroidListViewActivity.java

package com.onlinecodegeek.androidlistview;
 
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
 
public class AndroidListViewActivity extends ListActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
         
        // storing string resources into Array
        String[] adobe_products = getResources().getStringArray(R.array.adobe_products);
         
        // Binding resources Array to ListAdapter
        this.setListAdapter(new ArrayAdapter(this, R.layout.list_item, R.id.label, adobe_products));
         
    }
}

6. Now run your project you can see listview with list of array items. But on clicking single list item you can see no action. So we need to start new activity on selecting single list item. Launching new Activity on selecting single list item In my previous article i had explained how to switch between screens. Here i am going to show single list item details in new screen. 7. Now create new activity class under src folder. Right Click on src/package folder ⇒ New ⇒ Class and name it as SingleListItem. (SingleListItem.java) 8. Open your AndroidListViewActivity.java and modify the code to following. In the following code i am getting the selected list item string(product name) and sending it to new Activity. AndroidListViewActivity.java

package com.onlinecodegeek.androidlistview;
 
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
 
public class AndroidListViewActivity extends ListActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
         
        // storing string resources into Array
        String[] adobe_products = getResources().getStringArray(R.array.adobe_products);
         
        // Binding resources Array to ListAdapter
        this.setListAdapter(new ArrayAdapter(this, R.layout.list_item, R.id.label, adobe_products));
         
        ListView lv = getListView();
 
        // listening to single list item on click
        lv.setOnItemClickListener(new OnItemClickListener() {
          public void onItemClick(AdapterView parent, View view,
              int position, long id) {
               
              // selected item
              String product = ((TextView) view).getText().toString();
               
              // Launching new Activity on selecting single List Item
              Intent i = new Intent(getApplicationContext(), SingleListItem.class);
              // sending data to new activity
              i.putExtra("product", product);
              startActivity(i);
             
          }
        });
    }
}

Now in new activity we need to display the received from listview activity. 9. Create a new xml file under res/layout and name it as single_list_item_view.xml and type the following code. This XML file will be layout for SingleListItem.java single_list_item_view.xml

10. Now open your second activity file i.e SingleListItem.java and paste the following code. SingleListItem.java

package com.onlinecodegeek.androidlistview;
 
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;
 
public class SingleListItem extends Activity{
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.setContentView(R.layout.single_list_item_view);
         
        TextView txtProduct = (TextView) findViewById(R.id.product_label);
         
        Intent i = getIntent();
        // getting attached intent data
        String product = i.getStringExtra("product");
        // displaying selected product name
        txtProduct.setText(product);
         
    }
}

11. The final step is to add an entry of new activity name in AndroidManifest.xml file. Open you AndroidManifest.xml file and modify the code as below AndroidManifest.xml

12. Finally run your project by right clicking on your project folder ⇒ Run As ⇒ 1 Android Application.

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