Kotlin Android XML Parsing using DOM Parser

XML document is commonly used to share the data on the internet. The data provided in XML format are able to update frequently and parsing them is a common task for network-based apps.
In Android, there are three types of XML parsers to parse the XML data and read them in android applications, these are:

DOM Parser
SAX Parser
XMLPullParser

Android DOM (Document Object Model) parser uses an object-based approach to create and parse the XML files in android applications. The DOM parser loads the XML file into memory to parse the XML document. Due to this reason, it consumes more memory.

Example of XML Parsing using DOM Parser

In this example, we parse XML data and display them into ListView.

activity_main.xml

Add the ListView in the activity_main.xml layout.

< ?xml version="1.0" encoding="utf-8"?>  
< android.support.constraint.ConstraintLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"  
    xmlns:app="http://schemas.android.com/apk/res-auto"  
    xmlns:tools="http://schemas.android.com/tools"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    tools:context="example.javatpoint.com.kotlinxmlparsingusingdomparser.MainActivity">  
  
    < ListView  
            android:id="@+id/listView"  
            android:layout_width="match_parent"  
            android:layout_height="match_parent">  
     < /ListView>  
< /android.support.constraint.ConstraintLayout>

empdetail.xml

Create the XML document empdetail.xml in assets directory to parse the data using DOM parser.

< ?xml version="1.0" encoding="utf-8"?>  
< records>  
    < employee>  
        < name>Sachin Kumar< /name>  
        < salary>50000< /salary>  
        < designation>Developer< /designation>  
    < /employee>  
    < employee>  
        < name>Rahul Kumar< /name>  
        < salary>60000< /salary>  
        < designation>Team Leader< /designation>  
    < /employee>  
    < employee>  
        < name>John Mike< /name>  
        < salary>70000< /salary>  
        < designation>Manager< /designation>  
    < /employee>  
    < employee>  
        < name>Ajay Kumar  
        < salary>45000< /salary>  
        < designation>Developer< /designation>  
    < /employee>  
    < employee>  
        < name>Toni Nayer< /name>  
        < salary>55000< /salary>  
        < designation>Marketing< /designation>  
    < /employee>  
    < employee>  
        < name>Mr Bony< /name>  
        < salary>42000< /salary>  
        < designation>Sales< /designation>  
    < /employee>  
    < employee>  
        < name>Raj Kumar< /name>  
        < salary>30000< /salary>  
        < designation>Production< /designation>  
    < /employee>  
    < employee>  
        < name>Rahul Kumar< /name>  
        < salary>60000< /salary>  
        < designation>Team Leader< /designation>  
    < /employee>  
    < employee>  
        < name>John Mike< /name>  
        < salary>70000< /salary>  
        < designation>Manager< /designation>  
    < /employee>  
    < employee>  
        < name>Sachin Kumar< /name>  
        < salary>50000< /salary>  
        < designation>Developer< /designation>  
    < /employee>  
    < employee>  
        < name>Rahul Kumar< /name>  
        < salary>60000< /salary>  
        < designation>Team Leader< /designation>  
    < /employee>  
    < employee>  
        < name>John Mike< /name>  
        < salary>70000< /salary>  
        < designation>Manager< /designation>  
    < /employee>  
< /records>

custom_list.xml

Create a custom layout to display the list of data into ListView.

< ?xml version="1.0" encoding="utf-8"?>  
< LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    xmlns:app="http://schemas.android.com/apk/res-auto"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    android:orientation="horizontal">  
    < LinearLayout  
        android:layout_width="match_parent"  
        android:layout_height="wrap_content"  
        android:layout_weight="1"  
        android:orientation="vertical">  
  
        < TextView  
            android:id="@+id/name"  
            android:layout_width="match_parent"  
            android:layout_height="wrap_content"  
            android:text="name"  
            android:textStyle="bold"  
            android:layout_marginLeft="15dp"  
            android:layout_marginStart="15dp"  
            android:textAppearance="@style/Base.TextAppearance.AppCompat.Medium" />  
  
        < TextView  
            android:id="@+id/salary"  
            android:layout_width="match_parent"  
            android:layout_height="wrap_content"  
            android:text="salary"  
            android:layout_marginLeft="15dp"  
            android:layout_marginStart="15dp"  
            android:layout_marginTop="5dp"  
            android:textSize="16sp"/>  
        < TextView  
            android:id="@+id/designation"  
            android:layout_width="match_parent"  
            android:layout_height="wrap_content"  
            android:text="designation"  
            android:layout_marginLeft="15dp"  
            android:layout_marginStart="15dp"  
            android:layout_marginTop="5dp"  
            android:textSize="16sp"/>  
    < /LinearLayout>  
< /LinearLayout>

MainActivity.kt

Add the following code to read and parse the XML data using DOM parser. Create the instance of DocumentBuilderFactory, DocumentBuilder and Document objects.
The HashMap< String, String> is used to read the data from XML document and add them into ArrayList().

package example.javatpoint.com.kotlinxmlparsingusingdomparser  
  
import android.support.v7.app.AppCompatActivity  
import android.os.Bundle  
import android.widget.ListView  
import android.widget.SimpleAdapter  
import org.w3c.dom.Element  
import org.w3c.dom.Node  
import org.xml.sax.SAXException  
import java.io.IOException  
import javax.xml.parsers.DocumentBuilderFactory  
import javax.xml.parsers.ParserConfigurationException  
  
class MainActivity : AppCompatActivity() {  
    var empDataHashMap = HashMap< String, String>()  
    var empList: ArrayList< HashMap< String, String>> = ArrayList()  
    override fun onCreate(savedInstanceState: Bundle?) {  
        super.onCreate(savedInstanceState)  
        setContentView(R.layout.activity_main)  
        try {  
            val lv = findViewById< ListView>(R.id.listView)  
            val istream = assets.open("empdetail.xml")  
            val builderFactory = DocumentBuilderFactory.newInstance()  
            val docBuilder = builderFactory.newDocumentBuilder()  
            val doc = docBuilder.parse(istream)  
        //reading the tag "employee" of empdetail file  
            val nList = doc.getElementsByTagName("employee")  
            for (i in 0 until nList.getLength()) {  
                if (nList.item(0).getNodeType().equals(Node.ELEMENT_NODE) ) {  
               //creating instance of HashMap to put the data of node value           
           empDataHashMap = HashMap()  
                    val element = nList.item(i) as Element  
                    empDataHashMap.put("name", getNodeValue("name", element))  
                    empDataHashMap.put("salary", getNodeValue("salary", element))  
                    empDataHashMap.put("designation", getNodeValue("designation", element))  
          //adding the HashMap data to ArrayList  
                    empList.add(empDataHashMap)  
                }  
            }  
            val adapter = SimpleAdapter(this@MainActivity, empList, R.layout.custom_list, 
arrayOf("name", "salary", "designation"), intArrayOf(R.id.name, R.id.salary, R.id.designation))  
            lv.setAdapter(adapter)  
        } catch (e: IOException) {  
            e.printStackTrace()  
        } catch (e: ParserConfigurationException) {  
            e.printStackTrace()  
        } catch (e: SAXException) {  
            e.printStackTrace()  
        }  
  
    }  
    // function to return node value  
    protected fun getNodeValue(tag: String, element: Element): String {  
        val nodeList = element.getElementsByTagName(tag)  
        val node = nodeList.item(0)  
        if (node != null) {  
            if (node.hasChildNodes()) {  
                val child = node.getFirstChild()  
                while (child != null) {  
                    if (child.getNodeType() === Node.TEXT_NODE) {  
                        return child.getNodeValue()  
                    }  
                }  
            }  
        }  
        return ""  
    }  
}

Output:

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