Playing with audio recording in Android

Required permissions.

Class variables for audio file path, MediaRecorder, MediaPlayer and permission request code.

private var audioFilePath: String? = null
private var mediaRecorder: MediaRecorder? = null
private var mediaPlayer: MediaPlayer? = null
private val REQUEST_PERMISSION_CODE = 1000

Request audio and storage permissions.

if (ContextCompat.checkSelfPermission(activity, WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED
    || ContextCompat.checkSelfPermission(activity, RECORD_AUDIO) != PackageManager.PERMISSION_GRANTED) {
    ActivityCompat.requestPermissions(activity, arrayOf(WRITE_EXTERNAL_STORAGE, RECORD_AUDIO), REQUEST_PERMISSION_CODE)
}

Handle permission request result.

override fun onRequestPermissionsResult(requestCode: Int, permissions: Array, grantResults: IntArray) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults)
    when (requestCode) {
        REQUEST_PERMISSION_CODE -> {
            if (grantResults.isNotEmpty()) {
                val storagePermission = grantResults[0] == PackageManager.PERMISSION_GRANTED;
                val audioPermission = grantResults[1] == PackageManager.PERMISSION_GRANTED;

                if (storagePermission && audioPermission) {
                    Toast.makeText(activity, "Permission Granted", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(activity,"Permission Denied",Toast.LENGTH_SHORT).show();
                }
            }
        }
    }
}

Create audio file path. For simplicity, starting from there, the following code are functional only, without any UI/Views involved. Each of the following code block can be in a function itself.

audioFilePath = "${Environment.getExternalStorageDirectory().absolutePath}/recorded-audio.3gp"

Start recording sounds.

mediaRecorder = MediaRecorder()
mediaRecorder?.setAudioSource(MediaRecorder.AudioSource.MIC)
mediaRecorder?.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP)
mediaRecorder?.setAudioEncoder(MediaRecorder.OutputFormat.AMR_NB)
mediaRecorder?.setOutputFile(audioFilePath)

try {
    mediaRecorder?.prepare()
    mediaRecorder?.start()
} catch (e: IllegalStateException) {
    e.printStackTrace()
} catch (e: IOException) {
    e.printStackTrace()
}

Stop recording.

mediaRecorder?.stop()

Play the recorded sounds.

mediaPlayer = MediaPlayer()
try {
    mediaPlayer?.setDataSource(audioFilePath)
    mediaPlayer?.prepare()
} catch (e: IOException) {
    e.printStackTrace()
}

mediaPlayer?.start()

Stop playing the recorded sounds.

mediaPlayer?.stop()
mediaPlayer?.release()

https://developer.android.com/reference/android/media/MediaRecorder.html

https://developer.android.com/reference/android/media/MediaPlayer.html