XML Parsing in Android using XmlPullParser

In android, the XMLPullParser interface provides the functionality to parse the XML files in android applications. The XMLPullParser is a simple and efficient parser method to parse the XML data when compared to other parser methods such as DOM Parser and SAX Parser. The XMLPullParser has a method next() that provides access to high-level parsing events. The next() method will advance the parser to the next event. The following are the series of events available in XMLPullParser, which will be seen by the next() method.

1. START_DOCUMENT: The parser starts processing the XML document.
2. START_TAG: In this event, we can get the start tag in XML.
3. TEXT: In this event, we can read the text content using the getText() method.
4. END_TAG: An end tag was read.
5. END_DOCUMENT: No more events are available.

Note that we are going to implement this project using the Kotlin language. One may also perform XML Parsing in another two ways. Please refer to the below articles:

• XML Parsing in Android using DOM Parser
• XML Parsing in Android using SAX Parser

What we are going to do?

XMLPullParser scrutinizes an XML file with a series of events, such as START_DOCUMENT, START_TAG, TEXT, END_TAG, and END_DOCUMENT to parse the XML document. To read and parse XML files using XMLPullParser in android, one needs to create an instance of XMLPullParserFactory, and XMLPullParser.

Approach

To parse an XML file using a DOM parser in Android, we follow the following steps:

Step 1: Create a New Project

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. Note that select Kotlin as the programming language.

Step 2: Create an assets folder

Create an assets folder under the main folder in the Project Layout. Create an Android Resource File in this folder, where we shall put the information in the form of XML. Name this file as userdetails.xml. For doing so refer to the following steps:

Click on Project as shown on the left side of the below image. 

Expand until you find the main folder, right-click on it, go to New > Folder > Assets Folder

Then just click on the Finish button.

Now the asset folder is created successfully. Right-Click on the Assets Folder > New > Android Resource FIle 

Give it name Information, change type to XML, and finish.

Note: Sometimes, right-clicking on the Assets folder and creating an Android Resource File creates a file in the res folder. If this happens, cut our file and paste it directly into the assets folder. This happens due to some internal settings.

Paste this information which is in the form of XML, that is to be displayed in the userdetails.xml file. Below is the code for the userdetails.xml file.

<?xml version="1.0" encoding="utf-8"?>
<users>
    <user>
        <name>Tom</name>
        <designation>Actor and Producer</designation>
    </user>
    <user>
        <name>Danny</name>
        <designation>Music Director</designation>
    </user>
    <user>
        <name>Christopher</name>
        <designation>Writer</designation>
    </user>
</users>

Step 3: Working with the activity_main.xml file

Now go to the activity_main.xml file which represents the UI of the application. Create a ListView as shown. Below is the code for the activity_main.xml file.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <!--Display the list from list_row file-->
    <ListView
        android:id="@+id/user_list"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:dividerHeight="1dp" />
  
</LinearLayout>

 
Step 4: Create another layout file

Go to app > res > layout > right-click > New > Layout Resource File and name the file as list_row. list_row.xml file is used to show the data in the ListView. Below is the code for the list_row.xml file.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:padding="5dip">

    <!--TextView to display the name 
        from the userdetails file-->
    <TextView
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="17dp"
        android:textStyle="bold" />

    <!--TextView to display the designation 
        from the userdetails file-->
    <TextView
        android:id="@+id/designation"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/name"
        android:layout_marginTop="7dp"
        android:textColor="#343434"
        android:textSize="14dp" />

</RelativeLayout>

Step 5: Working with the MainActivity.kt file

Finally, go to the MainActivity.kt file, and refer to the following code. Below is the code for the MainActivity.kt file. Comments are added inside the code to understand the code in more detail.

import android.os.Bundle
import android.widget.ListAdapter
import android.widget.ListView
import android.widget.SimpleAdapter
import androidx.appcompat.app.AppCompatActivity
import org.xmlpull.v1.XmlPullParser
import org.xmlpull.v1.XmlPullParserException
import org.xmlpull.v1.XmlPullParserFactory
import java.io.IOException
import java.util.*

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        try {
            
            // creating a user list string hash map arraylist
            val userList = ArrayList<HashMap<String, String?>>()

            // creating a user string hashmap
            var user = HashMap<String, String?>()

            // declaring the list view from the layout file
            val lv = findViewById<ListView>(R.id.user_list)

            // input stream the userdetails.xml file
            val istream = assets.open("userdetails.xml")

            //creating a XmlPull parse Factory instance
            val parserFactory = XmlPullParserFactory.newInstance()
            val parser = parserFactory.newPullParser()

            // setting the namespaces feature to false
            parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false)

            // setting the input to the parser
            parser.setInput(istream, null)

            // working with the input stream
            var tag: String? = ""
            var text: String? = ""
            var event = parser.eventType
            while (event != XmlPullParser.END_DOCUMENT) {
                tag = parser.name
                when (event) {
                    XmlPullParser.START_TAG -> if (tag == "user") user = HashMap()
                    XmlPullParser.TEXT -> text = parser.text
                    XmlPullParser.END_TAG -> when (tag) {
                        "name" -> user["name"] = text
                        "designation" -> user["designation"] = text
                        "user" -> userList.add(user)
                    }
                }
                event = parser.next()
            }

            // List Adapter to broadcast the information to the list_rows.xml file
            val adapter: ListAdapter = SimpleAdapter(this, userList, R.layout.list_row,
                arrayOf("name", "designation"), intArrayOf(R.id.name, R.id.designation)
            )
            lv.adapter = adapter
        } catch (e: IOException) {
            e.printStackTrace()
        } catch (e: XmlPullParserException) {
            e.printStackTrace()
        }
    }
}

Output: Run on Emulator

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Article Tags :

• Kotlin
• Android
• Android-Misc