Kotlin Audio Recorder

import android.Manifest

import android.content.pm.PackageManager

import android.media.MediaRecorder

import android.os.Bundle

import android.os.Environment

import android.widget.Button

import android.widget.Toast

import androidx.appcompat.app.AppCompatActivity

import androidx.core.app.ActivityCompat

import androidx.core.content.ContextCompat

import java.io.IOException

class MainActivity : AppCompatActivity() {

    private lateinit var mediaRecorder: MediaRecorder

    private var outputFile: String = ""

    override fun onCreate(savedInstanceState: Bundle?) {

        super.onCreate(savedInstanceState)

        setContentView(R.layout.activity_main)

        val recordButton: Button = findViewById(R.id.record_button)

        if (ContextCompat.checkSelfPermission(this, Manifest.permission.RECORD_AUDIO) != PackageManager.PERMISSION_GRANTED) {

            ActivityCompat.requestPermissions(this, arrayOf(Manifest.permission.RECORD_AUDIO), 1)

        }

        outputFile = Environment.getExternalStorageDirectory().absolutePath + "/recording.3gp"

        mediaRecorder = MediaRecorder()

        mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC)

        mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP)

        mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB)

        mediaRecorder.setOutputFile(outputFile)

        recordButton.setOnClickListener {

            try {

                mediaRecorder.prepare()

                mediaRecorder.start()

                Toast.makeText(this, "Recording started", Toast.LENGTH_SHORT).show()

            } catch (e: IOException) {

                e.printStackTrace()

            }

        }

    }

    override fun onStop() {

        super.onStop()

        mediaRecorder.stop()

        mediaRecorder.release()

        Toast.makeText(this, "Recording stopped", Toast.LENGTH_SHORT).show()

    }

}