Kotlin Android XMLPullParser Tutorial

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 parsers are:

DOM Parser
SAX Parser
XMLPullParser

Android recommends to use XMLPullParser to parse the XML file rather than SAX and DOM because it is fast.

The org.xmlpull.v1.XmlPullParser interface provides the functionality to parse the XML document using XMLPullParser.

Events of XmlPullParser

The next() method of XMLPullParser moves the cursor pointer to the next event. Generally, we use four constants (works as the event) defined in the XMLPullParser interface.

START_TAG: An XML start tag will read.
TEXT: Text content was read the text content can be retrieved using the getText() method.
END_TAG: An end tag will read.
END_DOCUMENT: No more events are available.

Example of XML Parsing using XMLPullParser

In this example, we read the XML data and bind them into a ListView using XMLPullParser.

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.kotlinxmlparsingusingxmlpullparser.MainActivity">

    <ListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

    </ListView>

</android.support.constraint.ConstraintLayout>

employees.xml

Create the XML document employees.xml in assets directory to parse the data using XMLPullParser.

<?xml version="1.0" encoding="UTF-8"?>
<employees>
    <employee>
        <id>1</id>
        <name>Sachin Kumar</name>
        <salary>50000</salary>
    </employee>
    <employee>
        <id>2</id>
        <name>Rahul Kumar</name>
        <salary>60000</salary>
    </employee>
    <employee>
        <id>3</id>
        <name>John Mike</name>
        <salary>70000</salary>
    </employee>
    <employee>
        <id>4</id>
        <name>Ajay Kumar</name>
        <salary>45000</salary>
    </employee>
    <employee>
        <id>5</id>
        <name>Toni Nayer</name>
        <salary>55000</salary>
    </employee>
    <employee>
        <id>6</id>
        <name>Mr Bony</name>
        <salary>42000</salary>
    </employee>
    <employee>
        <id>7</id>
        <name>Raj Kumar</name>
        <salary>30000</salary>
    </employee>
    <employee>
        <id>8</id>
        <name>Rahul Kumar</name>
        <salary>60000</salary>
    </employee>
    <employee>
        <id>9</id>
        <name>John Mike</name>
        <salary>70000</salary>
    </employee>
    <employee>
        <id>10</id>
        <name>Sachin Kumar</name>
        <salary>50000</salary>
    </employee>
    <employee>
        <id>11</id>
        <name>Rahul Kumar</name>
        <salary>60000</salary>
    </employee>
    <employee>
        <id>12</id>
        <name>John Mike</name>
        <salary>70000</salary>
    </employee>
</employees>

Employee.kt

Create a data model class Employee.kt corresponds to the XML data file.

package example.javatpoint.com.kotlinxmlparsingusingxmlpullparser

class Employee {
    var id: Int = 0
    var name: String? = null
    var salary: Float = 0.toFloat()

    override fun toString(): String {
        return " Id = $id\n Name = $name\n Salary = $salary"
    }
}

XmlPullParserHandler.kt

Write the code to parse the XML file using XMLPullParser. In this class, we return all the employees in the list.

package example.javatpoint.com.kotlinxmlparsingusingxmlpullparser

import org.xmlpull.v1.XmlPullParserException
import org.xmlpull.v1.XmlPullParser
import org.xmlpull.v1.XmlPullParserFactory
import java.io.IOException
import java.io.InputStream

class XmlPullParserHandler {
    private val employees = ArrayList<Employee>()
    private var employee: Employee? = null
    private var text: String? = null

    fun parse(inputStream: InputStream): List<Employee> {
        try {
            val factory = XmlPullParserFactory.newInstance()
            factory.isNamespaceAware = true
            val parser = factory.newPullParser()
            parser.setInput(inputStream, null)
            var eventType = parser.eventType
            while (eventType != XmlPullParser.END_DOCUMENT) {
                val tagname = parser.name
                when (eventType) {
                    XmlPullParser.START_TAG -> if (tagname.equals("employee", ignoreCase = true)) {
                        // create a new instance of employee
                        employee = Employee()
                    }
                    XmlPullParser.TEXT -> text = parser.text
                    XmlPullParser.END_TAG -> if (tagname.equals("employee", ignoreCase = true)) {
                        // add employee object to list
                        employee?.let { employees.add(it) }
                    } else if (tagname.equals("id", ignoreCase = true)) {
                        employee!!.id = Integer.parseInt(text)
                    } else if (tagname.equals("name", ignoreCase = true)) {
                        employee!!.name = text
                    } else if (tagname.equals("salary", ignoreCase = true)) {
                        employee!!.salary = java.lang.Float.parseFloat(text)
                    }

                    else -> {
                    }
                }
                eventType = parser.next()
            }

        } catch (e: XmlPullParserException) {
            e.printStackTrace()
        } catch (e: IOException) {
            e.printStackTrace()
        }
        return employees
    }
}

MainActivity.kt

In this class, we send XML data into ArrayAdapter and bind them into ListView.

package example.javatpoint.com.kotlinxmlparsingusingxmlpullparser

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.ArrayAdapter
import android.widget.ListView
import java.io.IOException 


class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState) 
        setContentView(R.layout.activity_main)
        val listView = findViewById<ListView>(R.id.listView)
        var employees: List<Employee>? = null 
        try {
            val parser = XmlPullParserHandler()
            val istream = assets.open("employees.xml")
            employees = parser.parse(istream)

            val adapter = ArrayAdapter(this, android.R.layout.simple_list_item_1, employees)
            listView.adapter = adapter

        } catch (e: IOException) {
            e.printStackTrace()
        }
    }
}

Output: