How to use Volley Library to parse JSON in Android Kotlin App?

Kotlin Apps/ApplicationsMobile Development

This example demonstrates how to use Volley Library to parse JSON in Kotlin.

Step 1 − Create a new project in Android Studio, go to File ⇉ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?xml version="1.0" encoding="utf-8"?>
<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:padding="16sp"
   tools:context=".MainActivity">
   <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="50dp"
      android:text="Tutorials Point"
      android:textAlignment="center"
      android:textColor="@android:color/holo_green_dark"
      android:textSize="32sp"
      android:textStyle="bold" />
   <TextView
      android:id="@+id/textViewResult"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerInParent="true"
      android:textColor="@android:color/black"
      android:textSize="20sp" />
   <Button
      android:id="@+id/btnParse"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignParentBottom="true"
      android:layout_centerInParent="true"
      android:layout_marginBottom="20sp"
      android:text="Parse JSON" />
</RelativeLayout>

Step 3 − Add the following dependency to the build.gradle file−

implementation 'com.android.volley:volley:1.1.0'

Step 4 − Add the following code to MainActivity.kt

import android.os.Bundle
import android.widget.Button
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import com.android.volley.Request
import com.android.volley.RequestQueue
import com.android.volley.Response
import com.android.volley.toolbox.JsonObjectRequest
import com.android.volley.toolbox.Volley
import org.json.JSONException
class MainActivity : AppCompatActivity() {
   private lateinit var textView: TextView
   private var requestQueue: RequestQueue? = null
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
      textView = findViewById(R.id.textViewResult)
      val button: Button = findViewById(R.id.btnParse)
      requestQueue = Volley.newRequestQueue(this)
      button.setOnClickListener {
         jsonParse()
      }
   }
   private fun jsonParse() {
      val url = "https://api.myjson.com/bins/xbspb"
      val request = JsonObjectRequest(Request.Method.GET, url, null, Response.Listener {
          response ->try {
            val jsonArray = response.getJSONArray("employees")
            for (i in 0 until jsonArray.length()) {
               val employee = jsonArray.getJSONObject(i)
               val firstName = employee.getString("firstname")
               val age = employee.getInt("age")
               val mail = employee.getString("mail")
               textView.append("$firstName, $age, $mail\n\n")
            }
         } catch (e: JSONException) {
            e.printStackTrace()
         }
      }, Response.ErrorListener { error -> error.printStackTrace() })
      requestQueue?.add(request)
   }
}

Step 5 − Add the following code to androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="app.com.kotlipapp">
<uses-permission android:name="android.permission.INTERNET" />
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
      <activity android:name=".MainActivity">
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click the Run  icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen −

Click here to download the project code.

raja
Published on 21-Apr-2020 12:52:41
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