XML Parsing in Android

XML Parsing in Android Using DOM

What is an XML(Extensible Markup Language)?

Ans:  XML stands for Extensible Markup Language.XML was defined by W3C(World Wide Web Consortium).

An XML document consists of elements, each element has a start tag and an end tag,in between that content will be there.An XML file must be "well-formed".An XML file is called valid if it is well-formed.

An Well-formed xml look like bellow:

<?xml version="1.0"?>

<car>

  <name>BMW</name>

  <cost>2500000</cost>

</car>

XML Parsers in Android

Android supports two types of XML Parsers:

      1.    DOM(Document Object Model) Parser

      2.    SAX(Simple API for XML) Parser

 In this tutorial we will see how DOM(Document Object Model) parsing hapenning in android. To parse the xml file, we need xml data. So at first we will create a xml file, then we will parse it in our android device.

To Create XML file, see bellow steps:

Go to your Notepad application, Type the following code:

<?xml version="1.0"?> 

<computers> 

<brand> 

    <name>Apple</name> 

    <cost>45000</cost> 

</brand> 

<brand> 

     <name>Dell</name> 

     <cost>40000</cost> 

</brand> 

<brand> 

     <name>HP</name> 

     <cost>35000</cost> 

</brand> 

</computers>  

Then go File-> Save as -> testxml.xml.

After generating  this xml file, put this xml file Under assets folder in your android project.See Bellow how it will look like:

Creating Android Application Project for XML Parsing:

In Eclipse -> Create New Project(Named as TestDomParser). -> Provide Activity Name(Here name as MainActivity). This application building Android Version 4.2.2, API level 17.

MainActivity.java will look like this:

public class MainActivity extends Activity {

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        TextView tv_parse =(TextView)findViewById(R.id.tv);

        try{

            InputStream is = getAssets().open("testxml.xml");

            DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();

            DocumentBuilder dbBuilder = dbFactory.newDocumentBuilder();

            Document doc = dbBuilder.parse(is);

           

            Element element=doc.getDocumentElement(); 

            element.normalize();

           

            NodeList nList = doc.getElementsByTagName("brand");

            for (int i=0; i<nList.getLength(); i++) { 

                        Node node = nList.item(i); 

                        if (node.getNodeType() == Node.ELEMENT_NODE) { 

                                    Element elmnt = (Element) node; 

                                    tv_parse.setText(tv_parse.getText()+"\nCompany Name: " +                                                             getValue("name", elmnt)+"\n"); 

                                    tv_parse.setText(tv_parse.getText()+"Price: " + getValue("cost",                                                     elmnt)+"\n"); 

                                    tv_parse.setText(tv_parse.getText()+"**********************"); 

                                    } 

            }

        }catch(Exception e){

            e.printStackTrace();

        }

    }

    private static String getValue(String tag, Element element) { 

            NodeList nodeList = element.getElementsByTagName(tag).item(0).getChildNodes(); 

            Node node = (Node) nodeList.item(0); 

            return node.getNodeValue(); 

            } 

   

}

Activity_main.xml

<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:paddingBottom="@dimen/activity_vertical_margin"

    android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    tools:context=".MainActivity" >

    <TextView

        android:id="@+id/tv"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignParentLeft="true"

        android:layout_alignParentTop="true"

        android:textStyle="bold"

        android:textSize="15sp"

        android:layout_marginLeft="16dp"

        android:layout_marginTop="14dp"

        android:text="" />

</RelativeLayout>

Result:

Android JSON Parsing Using Async Task

JSON Parsing in Android using Asynctask

In Previous tutorial, mentioned about JSON types and how JSON parsing is happening without using asynctask. In this tutorial, I will talk about JSON parsing using Asynctask.  

What is Async Task?

 AsyncTask enables proper and easy use of the UI thread.This class allows to perform  background operations and publish results on the UI thread.

Async Task has Four Operations:
         1. onPreExecute()- It invoked before execution.
         2. onPostExecute()- It invoked after execution.
         3. doInBackground()- Main operation, write your long operation code.
         4. onPregressUpdate()- It indicates user on progress.

Async Task has Three generic types:

AsyncTask<Param, Progress, Result>
AsyncTask<{Type of Input},{Type of Update Unit},{Type of Update Result}>

In this tutorial, I am taking an example of following JSON which will give you list of News and each “NewsLines” have different Head-Lines and Date-Lines. You can get this JSON by accessing  http://mfeeds.timesofindia.indiatimes.com/Feeds/jsonfeed?newsid=3947071&amp;amp;format=simplejson

If you observe carefully, you can see { and ]. The main difference between these two is object and array. Curly bracket { represents JSONObject and Square bracket [ represents JSONArray.

In this example, I will create a button and after clicking on button the data will show in listview. So our main.xml will be like this:

Activity_main.xml

<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:paddingBottom="@dimen/activity_vertical_margin"

    android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    tools:context=".MainActivity" >

    <Button

        android:id="@+id/getdata"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignParentBottom="true"

        android:layout_centerHorizontal="true"

        android:layout_marginBottom="14dp"

        android:text="Get Data" />

    <ListView

        android:id="@android:id/list"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_above="@+id/getdata"

        android:layout_centerHorizontal="true" >

    </ListView>

</RelativeLayout>

Now we will create Parser class. This parser class is used to execute the JSON link and get the JSON data and returns JSON Object.

public class Parser {

    static InputStream is = null;

    static JSONObject jObj = null;

    static String json = "";

    public JSONObject getJSONData(String url){

            try{

                        DefaultHttpClient client = new DefaultHttpClient();

                        HttpPost post = new HttpPost(url);

                        HttpResponse response = client.execute(post);

                        HttpEntity entity = response.getEntity();

                        is = entity.getContent();

            }catch (UnsupportedEncodingException e) {

            e.printStackTrace();

        } catch (ClientProtocolException e) {

            e.printStackTrace();

        } catch (IOException e) {

            e.printStackTrace();

        }

            try {

            BufferedReader reader = new BufferedReader(new InputStreamReader(

                    is, "iso-8859-1"), 8);

            StringBuilder sb = new StringBuilder();

            String line = null;

            while ((line = reader.readLine()) != null) {

                sb.append(line + "\n");

            }

            is.close();

            json = sb.toString();

        } catch (Exception e) {

            Log.e("Buffer Error", "Error converting result " + e.toString());

        }

            try {

            jObj = new JSONObject(json);

        } catch (JSONException e) {

            Log.e("JSON Parser", "Error parsing data " + e.toString());

        }

        return jObj;

    }

}

In NewsLines, there are multiple strings i.e HeadLine and DateLine. So you need to define these in your MainActivity class.

    private static final String NEWS = "NewsML";

        private static final String NEWS_LINE = "NewsLines";

        private static final String HEAD_LINE = "HeadLine";

        private static final String DATE_LINE = "DateLine";

After button click, it will execute AsyncTask, so you need to write like this way:

Btngetdata.setOnClickListener(new OnClickListener() {

                                   

                                    @Override

                                    public void onClick(View v) {

                                                new JSONParse().execute();

                                    }

                        });

Here JSONParse is a class for Asynctask operation.By using this JSONParse class, it will get the data and fill in the list view. So JSONPasre class will look like this:

private class JSONParse extends AsyncTask<String, Integer, ArrayList<HashMap<String, String>>>{

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

                        
        private ProgressDialog pDialog;

        protected void onPreExecute() {

            super.onPreExecute();

            pDialog = new ProgressDialog(MainActivity.this);

            pDialog.setMessage("Loading Data ...");

            pDialog.setIndeterminate(false);

            pDialog.setCancelable(true);

            pDialog.show();

        }

                        @Override

        protected ArrayList<HashMap<String, String>> doInBackground(String... params) {

             Parser jParser = new Parser();

            JSONObject json = jParser.getJSONData(url);

            try{

                        news = json.getJSONArray(NEWS);

                        for(int i=0;i<news.length();i++){

                                    JSONObject object = news.getJSONObject(i);

                                    JSONObject newsline = object.getJSONObject(NEWS_LINE);

                                    String headLine = newsline.getString(HEAD_LINE);

                                    String dateLine = newsline.getString(DATE_LINE);

                                    HashMap<String, String> map = new HashMap<String, String>();

                                    map.put(HEAD_LINE, headLine);

                                    map.put(DATE_LINE, dateLine);

                                    newsList.add(map);

                        }

            }catch(JSONException e){

                        e.printStackTrace();

            }

            return newsList;

           }//Ending doInBackground

                        @Override

           protected void onPostExecute(ArrayList<HashMap<String, String>> result) {

                                    super.onPostExecute(result);

                                    pDialog.dismiss();

                                    String []from = {HEAD_LINE,DATE_LINE};

                                    int []to = {R.id.tv_headLn,R.id.tv_dateLn};

                                    ListAdapter adapter = new SimpleAdapter(MainActivity.this, result,R.layout.listview_item, from, to);

                                    setListAdapter(adapter);

                        }

So the MainActivity class will look like this:

MainActivity.java

public class MainActivity extends ListActivity {

    Button Btngetdata;

    private static final String NEWS = "NewsML";

    private static final String NEWS_LINE = "NewsLines";

    private static final String HEAD_LINE = "HeadLine";

    private static final String DATE_LINE = "DateLine";

    JSONArray news = null;

    //URL to get JSON Array

    private static String url = "http://mfeeds.timesofindia.indiatimes.com/Feeds/jsonfeed?newsid=3947071&amp;amp;format=simplejson";

            @Override

            protected void onCreate(Bundle savedInstanceState) {

                        super.onCreate(savedInstanceState);

                        requestWindowFeature(Window.FEATURE_NO_TITLE);

                        setContentView(R.layout.activity_main);

                        Btngetdata = (Button)findViewById(R.id.getdata);

                        Btngetdata.setOnClickListener(new OnClickListener() {

                                   

                                    @Override

                                    public void onClick(View v) {

                                                new JSONParse().execute();

                                    }

                        });

            }

        private class JSONParse extends AsyncTask<String, Integer, ArrayList<HashMap<String, String>>>{

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

            private ProgressDialog pDialog;

            protected void onPreExecute() {

            super.onPreExecute();

            pDialog = new ProgressDialog(MainActivity.this);

            pDialog.setMessage("Loading Data ...");

            pDialog.setIndeterminate(false);

            pDialog.setCancelable(true);

            pDialog.show();

        }

                        @Override

        protected ArrayList<HashMap<String, String>> doInBackground(String... params) {

             Parser jParser = new Parser();

            JSONObject json = jParser.getJSONData(url);

            try{

                        news = json.getJSONArray(NEWS);

                        for(int i=0;i<news.length();i++){

                                    JSONObject object = news.getJSONObject(i);

                                    JSONObject newsline = object.getJSONObject(NEWS_LINE);

                                    String headLine = newsline.getString(HEAD_LINE);

                                    String dateLine = newsline.getString(DATE_LINE);

                                    HashMap<String, String> map = new HashMap<String, String>();

                                    map.put(HEAD_LINE, headLine);

                                    map.put(DATE_LINE, dateLine);

                                    newsList.add(map);

                        }

            }catch(JSONException e){

                        e.printStackTrace();

            }

            return newsList;

         }

                        @Override

        protected void onPostExecute(ArrayList<HashMap<String, String>> result) {

                                    

                                    super.onPostExecute(result);

                                    pDialog.dismiss();

                                    String []from = {HEAD_LINE,DATE_LINE};

                                    int []to = {R.id.tv_headLn,R.id.tv_dateLn};

                                    ListAdapter adapter = new SimpleAdapter(MainActivity.this, result, R.layout.listview_item, from, to);

                                    setListAdapter(adapter);

                        }

                       

            }

}

Result: