How to develop an Speech recognizer in Android without Google API in Kotlin?

This example demonstrates how to develop an Speech recognizer in Android without Google API in 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.

Example

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical">
   <ImageView
      android:id="@+id/imageView"
      android:layout_width="200dp"
      android:layout_height="200dp"
      android:layout_centerInParent="true"
      android:src="@drawable/ic_mic" />
   <ProgressBar
      android:id="@+id/progressBar"
      style="?android:attr/progressBarStyleHorizontal"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_below="@+id/toggleButton"
      android:layout_alignParentStart="true"
      android:layout_marginTop="28dp"
      android:paddingLeft="10dp"
      android:paddingRight="10dp" />
   <TextView
      android:id="@+id/textView"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_below="@+id/progressBar"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="47dp" />
   <ToggleButton
      android:id="@+id/toggleButton"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignParentTop="true"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="26dp"
      android:text="ToggleButton" />
</RelativeLayout>

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

Example

import android.Manifest
import android.content.Intent
import android.content.pm.PackageManager
import android.os.Bundle
import android.speech.RecognitionListener
import android.speech.RecognizerIntent
import android.speech.SpeechRecognizer
import android.util.Log
import android.view.View
import android.widget.ProgressBar
import android.widget.TextView
import android.widget.Toast
import android.widget.ToggleButton
import androidx.appcompat.app.AppCompatActivity
import androidx.core.app.ActivityCompat
class MainActivity : AppCompatActivity(), RecognitionListener {
   private val permission = 100
   private lateinit var returnedText: TextView
   private lateinit var toggleButton: ToggleButton
   private lateinit var progressBar: ProgressBar
   private lateinit var speech: SpeechRecognizer
   private lateinit var recognizerIntent: Intent
   private var logTag = "VoiceRecognitionActivity"
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
      returnedText = findViewById(R.id.textView)
      progressBar = findViewById(R.id.progressBar)
      toggleButton = findViewById(R.id.toggleButton)
      progressBar.visibility = View.VISIBLE
      speech = SpeechRecognizer.createSpeechRecognizer(this)
      Log.i(logTag, "isRecognitionAvailable: " + SpeechRecognizer.isRecognitionAvailable(this))
      speech.setRecognitionListener(this)
      recognizerIntent = Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH)
      recognizerIntent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_PREFERENCE, "US-en")
      recognizerIntent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,
      RecognizerIntent.LANGUAGE_MODEL_FREE_FORM)
      recognizerIntent.putExtra(RecognizerIntent.EXTRA_MAX_RESULTS, 3)
      toggleButton.setOnCheckedChangeListener { _, isChecked ->
         if (isChecked) {
            progressBar.visibility = View.VISIBLE
            progressBar.isIndeterminate = true
            ActivityCompat.requestPermissions(this@MainActivity,
            arrayOf(Manifest.permission.RECORD_AUDIO),
            permission)
         } else {
            progressBar.isIndeterminate = false
            progressBar.visibility = View.VISIBLE
            speech.stopListening()
         }
      }
   }
   override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<String?>,
   grantResults: IntArray) {
      super.onRequestPermissionsResult(requestCode, permissions, grantResults)
      when (requestCode) {
         permission -> if (grantResults.isNotEmpty() && grantResults[0] == PackageManager
         .PERMISSION_GRANTED) {
            speech.startListening(recognizerIntent)
         } else {
            Toast.makeText(this@MainActivity, "Permission Denied!",
            Toast.LENGTH_SHORT).show()
         }
      }
   }
   override fun onStop() {
      super.onStop()
      speech.destroy()
      Log.i(logTag, "destroy")
   }
   override fun onReadyForSpeech(params: Bundle?) {
      TODO("Not yet implemented")
   }
   override fun onRmsChanged(rmsdB: Float) {
      progressBar.progress = rmsdB.toInt()
   }
   override fun onBufferReceived(buffer: ByteArray?) {
      TODO("Not yet implemented")
   }
   override fun onPartialResults(partialResults: Bundle?) {
      TODO("Not yet implemented")
   }
   override fun onEvent(eventType: Int, params: Bundle?) {
      TODO("Not yet implemented")
   }
   override fun onBeginningOfSpeech() {
      Log.i(logTag, "onBeginningOfSpeech")
      progressBar.isIndeterminate = false
      progressBar.max = 10
   }
   override fun onEndOfSpeech() {
      progressBar.isIndeterminate = true
      toggleButton.isChecked = false
   }
   override fun onError(error: Int) {
      val errorMessage: String = getErrorText(error)
      Log.d(logTag, "FAILED $errorMessage")
      returnedText.text = errorMessage
      toggleButton.isChecked = false
   }
   private fun getErrorText(error: Int): String {
      var message = ""
      message = when (error) {
         SpeechRecognizer.ERROR_AUDIO -> "Audio recording error"
         SpeechRecognizer.ERROR_CLIENT -> "Client side error"
         SpeechRecognizer.ERROR_INSUFFICIENT_PERMISSIONS -> "Insufficient permissions"
         SpeechRecognizer.ERROR_NETWORK -> "Network error"
         SpeechRecognizer.ERROR_NETWORK_TIMEOUT -> "Network timeout"
         SpeechRecognizer.ERROR_NO_MATCH -> "No match"
         SpeechRecognizer.ERROR_RECOGNIZER_BUSY -> "RecognitionService busy"
         SpeechRecognizer.ERROR_SERVER -> "error from server"
         SpeechRecognizer.ERROR_SPEECH_TIMEOUT -> "No speech input"
         else -> "Didn't understand, please try again."
      }
      return message
   }
   override fun onResults(results: Bundle?) {
      Log.i(logTag, "onResults")
      val matches = results!!.getStringArrayList(SpeechRecognizer.RESULTS_RECOGNITION)
      var text = ""
      for (result in matches) text = """
      $result
      """.trimIndent()
      returnedText.text = text
   }
}

Step 4 − Add the following code to androidManifest.xml

Example

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="app.com.myapplication">
   <uses-permission android:name="android.permission.RECORD_AUDIO" />
   <uses-permission android:name="android.permission.INTERNET" />
   <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 −