@Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    Utils.getInstance().customeTitle(this);

    // initialize the TextView
    textviewQuestion = (TextView) findViewById(R.id.textViewQuestion);
    textviewAnswer = (TextView) findViewById(R.id.textViewAnswer);
    textviewXX = (TextView) findViewById(R.id.textViewXX);
    textviewYY = (TextView) findViewById(R.id.textViewYY);

    // Question template title
    textviewSubject = (TextView) findViewById(R.id.textViewSubject);

    // Initialize the Button and set the onClickListener for Button
    buttonLeft = (Button) findViewById(R.id.buttonLeft);
    buttonLeft.setOnClickListener(this);
    buttonRight = (Button) findViewById(R.id.buttonRight);
    buttonRight.setOnClickListener(this);
    buttonShowAnswer = (Button) findViewById(R.id.buttonAnswer);
    buttonShowAnswer.setOnClickListener(this);

    toggleButtonOnOff = (ToggleButton) findViewById(R.id.voice_on_off);

    // Import and initialize the string-array elements from values folder
    collectionQuestions = getResources().getStringArray(R.array.collection_questions);
    collectionAnswers = getResources().getStringArray(R.array.collection_answers);

    // Set the first question index
    index = 0;

    // Get the default answer in TextView.
    defaultTextviewAnswer = getResources().getString(R.string.answer);

    // Set the first question in page.
    textviewQuestion.setText(collectionQuestions[index]);
    textviewAnswer.setText(defaultTextviewAnswer);
    textviewXX.setText(String.valueOf(index + 1) + "/");
    textviewYY.setText(String.valueOf(collectionQuestions.length));

    textviewSubject.setText("Java - Collections");

    // Text to speech conversion
    textToSpeech =
        Utils.getInstance()
            .textToSpeechConversion(toggleButtonOnOff, getApplicationContext(), this);
    Utils.getInstance()
        .addTextToSpeechListener(
            toggleButtonOnOff, getApplicationContext(), textviewAnswer, defaultTextviewAnswer);
  }
 @Override
 public void onClick(View v) {
   index =
       Utils.getInstance()
           .onClickEvent(
               v,
               index,
               textviewAnswer,
               textviewQuestion,
               textviewXX,
               collectionQuestions,
               collectionAnswers,
               defaultTextviewAnswer,
               textToSpeech);
 }
 @Override
 protected void onDestroy() {
   super.onDestroy();
   Utils.getInstance().stopTextToSpeech(true, textToSpeech);
 }