MainActivity.kt
package com.cfsuman.kotlintutorials
import android.app.Activity
import android.os.Bundle
import android.text.method.ScrollingMovementMethod
import android.util.Log
import android.widget.*
import com.android.volley.Request
import com.android.volley.toolbox.JsonObjectRequest
import org.json.JSONException
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 textView = findViewById<TextView>(R.id.textView)
// Make text view text scrollable
textView.movementMethod = ScrollingMovementMethod()
// Data URL
val url = "https://pastebin.com/raw/2bW31yqa"
// Run volley
button.setOnClickListener {
// disable the button itself
it.isEnabled = false
textView.text = ""
val jsonObjectRequest = JsonObjectRequest(
Request.Method.GET, url, null,
{ response ->
// Process the JSON
try {
// Get the JSON array
val array = response.getJSONArray("students")
// Loop through the array elements
for (i in 0 until array.length()) {
// Get current json object
val student = array.getJSONObject(i)
// Get the current student (json object) data
val firstName = student.getString("firstname")
val lastName = student.getString("lastname")
val age = student.getString("age")
// Display the formatted json data in text view
textView.append("$firstName $lastName\nage : $age")
textView.append("\n\n")
}
} catch (e: JSONException) {
e.printStackTrace()
}
}, { error ->
Log.d("error", error.toString())
}
)
// Access the RequestQueue through singleton class.
VolleySingleton.getInstance(this)
.addToRequestQueue(jsonObjectRequest)
}
}
}
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" />
<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'
