How to Play an arbitrary tone in Android using Kotlin?

This example demonstrates how to Play an arbitrary tone in Android using 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"?> <LinearLayout 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:gravity="center"    android:orientation="vertical"    android:padding="16dp"    tools:context=".MainActivity">    <ImageView       android:layout_width="200dp"       android:layout_height="300dp"       android:src="@drawable/ic_music" />    <TextView       android:layout_width="wrap_content"       android:layout_height="wrap_content"       android:text="Increase the emulator Volume, Listen to the arbitrary tone!"       android:textColor="@android:color/background_dark"       android:textSize="16sp"       android:textStyle="bold|italic" /> </LinearLayout>

Step 3 − Add the following code to src/MainActivity.kt

import android.media.AudioFormat import android.media.AudioManager import android.media.AudioTrack import android.os.Bundle import android.os.Handler import androidx.appcompat.app.AppCompatActivity import kotlin.experimental.and import kotlin.math.sin class MainActivity : AppCompatActivity() {    private val duration = 10    private val sampleRate = 8000    private val numSamples = duration * sampleRate    private val sample = DoubleArray(numSamples)    private val generatedSnd = ByteArray(2 * numSamples)    var handler: Handler = Handler()    override fun onCreate(savedInstanceState: Bundle?) {       super.onCreate(savedInstanceState)       setContentView(R.layout.activity_main)       title = "KotlinApp"    }    override fun onResume() {       super.onResume()       val thread = Thread(Runnable {          genTone()          handler.post { playSound() }       })       thread.start()    }    private fun genTone() {       for (i in 0 until numSamples) {          val freqOfTone = 440.0          sample[i] =          sin(2 * Math.PI * i / (sampleRate / freqOfTone))       }       var idx = 0       for (dVal in sample) {          val `val` = (dVal * 32767).toShort()          generatedSnd[idx++] = `val`.and(0x00ff).toByte()          generatedSnd[idx++] = `val`.and(0xff00 ushr 8).toByte()       }    }    private fun playSound() {       val audioTrack = AudioTrack(          AudioManager.STREAM_MUSIC,          sampleRate, AudioFormat.CHANNEL_OUT_MONO,          AudioFormat.ENCODING_PCM_16BIT, generatedSnd.size,          AudioTrack.MODE_STATIC       )       audioTrack.write(generatedSnd, 0, generatedSnd.size)       audioTrack.play()    } }

Step 4 − 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.q11">    <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