XmlParsing Using XmlPullParser in Android Studio

Introduction

In this article, you will learn about XML parsing with the pull parser

XML Parsing

XML parsing is a process of converting data from a server in a machine-readable form.

XML pull parser

The XML pull parser is an interface that defines the parsing functionality. It provides two key methods next() that provide access to high-level parsing events. The current event state of the parser can be determined by the geteventType() method. Initially, the parser lies in the START_DOCUMENT state.

The following are the events seen by next():

START_TAG:
an XML start tag was read.
Text:
Text content was read. The text content was retrieved using the getText() method.
END_TAG:
A tag was read.
END_DOCUMENT:
No more events are available.

Step 1

Create an XML file and write this:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".MainActivity">
<ListView
android:id="@android:id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>
</RelativeLayout>

Step 2

Create a Java file MainActivity.java and write this:

import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlPullParserFactory;
import java.io.IOException;
import java.io.StringReader;
import java.io.UnsupportedEncodingException;
public class MainActivity extends ListActivity {
private static String BASE_URL = "http://maps.googleapis.com/maps/api/geocode/xml?address=NewDelhi&sensor=false";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
(new ProgressTask(MainActivity.this)).execute();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public class ProgressTask extends AsyncTask<String, Void, Boolean> {
private ProgressDialog dialog;
private Context context;
public ProgressTask(ListActivity activity) {
Log.i("1", "Called");
context = activity;
dialog = new ProgressDialog(context);
}
protected void onPreExecute() {
this.dialog.setMessage("Progress start");
this.dialog.show();
}
@Override
protected void onPostExecute(final Boolean success) {
if (dialog.isShowing()) {
dialog.dismiss();
}
}
protected Boolean doInBackground(final String... args) {
String xml = getXmlFromUrl(BASE_URL);
// useParserType1(xml);
useParserType2(xml);
return null;
}
}
//DOM Parser
public void useParserType1(String xml){
XmlParsingType1 parser = new XmlParsingType1();
Document doc = parser.getDomElement(xml); // getting DOM element
NodeList GeocodeResponse = doc.getElementsByTagName("location");
for (int i = 0; i < GeocodeResponse.getLength(); i++) {
Element e = (Element) GeocodeResponse.item(i);
Log.i("xml", parser.getValue(e,"lat"));
Log.i("xml", parser.getValue(e,"lng"));
}
}
//XmlPull Parser
public void useParserType2(String xml){
try{
Boolean flagLocation = false;
Boolean flagLatitude = false;
Boolean flagLongitude = false;
XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
factory.setNamespaceAware(true);
XmlPullParser xpp = factory.newPullParser();
xpp.setInput(new StringReader(xml));
int eventType = xpp.getEventType();
while (eventType != XmlPullParser.END_DOCUMENT) {
if(eventType == XmlPullParser.START_DOCUMENT) {
} else if(eventType == XmlPullParser.END_DOCUMENT) {
} else if(eventType == XmlPullParser.START_TAG) {
if (xpp.getName().equalsIgnoreCase("location")) flagLocation=true;
if (flagLocation && xpp.getName().equalsIgnoreCase("lat")) flagLatitude=true;
if (flagLocation && xpp.getName().equalsIgnoreCase("lng")) flagLongitude=true;
} else if(eventType == XmlPullParser.END_TAG) {
if (xpp.getName().equalsIgnoreCase("location")) flagLocation=false;
if (flagLocation && xpp.getName().equalsIgnoreCase("lat")) flagLatitude=false;
if (flagLocation && xpp.getName().equalsIgnoreCase("lng")) flagLongitude=false;
} else if(eventType == XmlPullParser.TEXT) {
if (flagLatitude)
Log.i("Latitude: ", xpp.getText());
if (flagLongitude)
Log.i("Longitude: ", xpp.getText());
}
eventType = xpp.next();
}
}catch (XmlPullParserException e){
e.printStackTrace();
}catch (IOException e){
e.printStackTrace();
}
}
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;
}
}

Step 3

Create another Java class file XMLParser.java and write this:

import android.util.Log;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import java.io.IOException;
import java.io.StringReader;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
/**
* Created by naveen on 19/06/13.
*/
public class XmlParsingType1 {
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;
}
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 "";
}
}

Output

See Logcat