MainActivity.kt
package com.cfsuman.kotlintutorials
import android.app.Activity
import android.os.Bundle
import android.text.method.ScrollingMovementMethod
import android.view.View
import android.widget.*
import com.android.volley.Request
import com.android.volley.toolbox.JsonArrayRequest
import org.json.JSONException
import org.json.JSONObject
class MainActivity : Activity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// get the widgets reference from XML layout
val button = findViewById<Button>(R.id.button)
val progressBar = findViewById<ProgressBar>(R.id.progressBar)
val textView = findViewById<TextView>(R.id.textView)
// make text view content scrollable
textView.movementMethod = ScrollingMovementMethod()
// url to get json array
val url = "https://pastebin.com/raw/Em972E5s"
// get json array from url using volley network library
button.setOnClickListener {
// disable the button itself
it.isEnabled = false
progressBar.visibility = View.VISIBLE
// request json array response from the provided url
val request = JsonArrayRequest(
Request.Method.GET, // method
url, // url
null, // json request
{response -> // response listener
try {
textView.text = ""
// loop through the array elements
for (i in 0 until response.length()){
// get current json object as student instance
val student: JSONObject = response.getJSONObject(i)
// get the current student (json object) data
val firstName: String = student
.getString("firstname")
val lastName: String = student
.getString("lastname")
val age: Int = student.getInt("age")
// display the formatted json data in text view
textView.append("$firstName " +
"$lastName\nAge : $age\n\n")
}
}catch (e: JSONException){
textView.text = e.message
}
progressBar.visibility = View.INVISIBLE
},
{error -> // error listener
textView.text = error.message
progressBar.visibility = View.INVISIBLE
}
)
// add network request to volley queue
VolleySingleton.getInstance(applicationContext)
.addToRequestQueue(request)
}
}
}
VolleySingleton.kt
package com.cfsuman.kotlintutorials
import android.content.Context
import com.android.volley.Request
import com.android.volley.RequestQueue
import com.android.volley.toolbox.Volley
class VolleySingleton constructor(context: Context) {
companion object {
@Volatile
private var INSTANCE: VolleySingleton? = null
fun getInstance(context: Context) =
INSTANCE ?: synchronized(this) {
INSTANCE ?: VolleySingleton(context).also {
INSTANCE = it
}
}
}
private val requestQueue: RequestQueue by lazy {
// applicationContext is key, it keeps you from leaking the
// Activity or BroadcastReceiver if someone passes one in.
Volley.newRequestQueue(context.applicationContext)
}
fun <T> addToRequestQueue(req: Request<T>) {
requestQueue.add(req)
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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"
android:background="#DCDCDC"
android:padding="24dp">
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Run Volley"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ProgressBar
android:id="@+id/progressBar"
style="?android:attr/progressBarStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:visibility="invisible"
app:layout_constraintBottom_toBottomOf="@+id/button"
app:layout_constraintStart_toEndOf="@+id/button"
app:layout_constraintTop_toTopOf="@+id/button" />
<TextView
android:id="@+id/textView"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginTop="16dp"
android:fontFamily="sans-serif"
android:textSize="24sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/button"
tools:text="TextView" />
</androidx.constraintlayout.widget.ConstraintLayout>
gradle dependencies
// Volley network library
implementation 'com.android.volley:volley:1.2.1'

- android kotlin - Volley JsonObjectRequest
- android kotlin - Volley image request
- android kotlin - Volley string request
- android kotlin - Chip center text
- android kotlin - Chip border color
- android kotlin - Chip background color
- android kotlin - Chip checked color programmatically
- android kotlin - ChipGroup get selected chips
- android kotlin - ChipGroup add chip programmatically
- android kotlin - ChipGroup single selection
- android kotlin - NumberPicker string values
- android kotlin - NumberPicker divider height
- android kotlin - NumberPicker remove divider
- android kotlin - NumberPicker divider color
- android kotlin - NumberPicker text size