Android Text to Speech Tutorial

1- Overview

Converting text into speech is a feature included in Android from API 21 which allows you to transfer a text to speech. It supports many different languages. To perform this function you need to use android.speech.tts.TextToSpeech class.
To Android API Level 23, these locales below will be supported: 
  • en_US
  • de_DE
  • fr
  • es_ES
  • de
  • en
  • it_IT
  • it
  • en_GB
  • es
  • fr_FR

2- Text To Speech example

Create a project named TextToSpeechDemo:
interface design:
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="org.o7planning.texttospeechdemo.MainActivity">

    <RadioGroup
        android:layout_width="match_parent"
        android:layout_height="150dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:id="@+id/radioGroup">

        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="English"
            android:id="@+id/radio_en"
            android:checked="true" />

        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="France"
            android:id="@+id/radio_fr"
            android:checked="false" />
    </RadioGroup>

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/editText"
        android:layout_below="@+id/radioGroup"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignRight="@+id/radioGroup"
        android:layout_alignEnd="@+id/radioGroup" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Speak"
        android:id="@+id/button"
        android:layout_below="@+id/editText"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="58dp" />

</RelativeLayout>

Min SDK Level

Text To Speech requires Android API Level> = 21 so you need to configure in build.gradle (Module: app)  file 

minSdkVersion 21
 
MainActivity.java
package org.o7planning.texttospeechdemo;

import android.app.Activity;
import android.os.Bundle;

import android.speech.tts.TextToSpeech;

import android.util.Log;
import android.view.View;

import android.widget.Button;
import android.widget.CompoundButton;
import android.widget.EditText;

import java.util.Locale;
import java.util.Set;
import java.util.UUID;

import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;

public class MainActivity extends Activity {
   private TextToSpeech textToSpeech;
   private EditText editText_text;
   private Button button;
   private RadioButton radio_en;
   private RadioButton radio_fr;
   RadioGroup radioGroup;

   private boolean ready;

   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
       editText_text = (EditText) findViewById(R.id.editText);
       button = (Button) findViewById(R.id.button);
       radio_en = (RadioButton) findViewById(R.id.radio_en);
       radio_fr = (RadioButton) findViewById(R.id.radio_fr);
       radioGroup = (RadioGroup) findViewById(R.id.radioGroup);


       textToSpeech = new TextToSpeech(getApplicationContext(), new TextToSpeech.OnInitListener() {
           @Override
           public void onInit(int status) {
               Log.e("TTS", "TextToSpeech.OnInitListener.onInit...");
               printOutSupportedLanguages();
               setTextToSpeechLanguage();
           }
       });
       radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {

           @Override
           public void onCheckedChanged(RadioGroup group, int checkedId) {
               setTextToSpeechLanguage();
           }
       });
       button.setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View v) {
               speakOut();
           }
       });
   }

   private void printOutSupportedLanguages()  {
       // Supported Languages
       Set<Locale> supportedLanguages = textToSpeech.getAvailableLanguages();
       if(supportedLanguages!= null) {
           for (Locale lang : supportedLanguages) {
               Log.e("TTS", "Supported Language: " + lang);
           }
       }
   }


   @Override
   public void onPause() {
       if (textToSpeech != null) {
           textToSpeech.stop();
           textToSpeech.shutdown();
       }
       super.onPause();
   }

   private void speakOut() {
       if (!ready) {
           Toast.makeText(this, "Text to Speech not ready", Toast.LENGTH_LONG).show();
           return;
       }
       // Text to Speak
       String toSpeak = editText_text.getText().toString();
       Toast.makeText(this, toSpeak, Toast.LENGTH_SHORT).show();
       // A random String (Unique ID).
       String utteranceId = UUID.randomUUID().toString();
       textToSpeech.speak(toSpeak, TextToSpeech.QUEUE_FLUSH, null, utteranceId);
   }

   private Locale getUserSelectedLanguage() {
       int checkedRadioId = this.radioGroup.getCheckedRadioButtonId();
       if (checkedRadioId == R.id.radio_en) {
           return Locale.ENGLISH;
       } else if (checkedRadioId == R.id.radio_fr) {
           return Locale.FRANCE;
       }
       return null;
   }


   private void setTextToSpeechLanguage() {
       Locale language = this.getUserSelectedLanguage();
       if (language == null) {
           this.ready = false;
           Toast.makeText(this, "Not language selected", Toast.LENGTH_SHORT).show();
           return;
       }
       int result = textToSpeech.setLanguage(language);
       if (result == TextToSpeech.LANG_MISSING_DATA) {
           this.ready = false;
           Toast.makeText(this, "Missing language data", Toast.LENGTH_SHORT).show();
           return;
       } else if (result == TextToSpeech.LANG_NOT_SUPPORTED) {
           this.ready = false;
           Toast.makeText(this, "Language not supported", Toast.LENGTH_SHORT).show();
           return;
       } else {
           this.ready = true;
           Locale currentLanguage = textToSpeech.getVoice().getLocale();
           Toast.makeText(this, "Language " + currentLanguage, Toast.LENGTH_SHORT).show();
       }
   }


}
Running apps: