set title bar name of a activity

I'm trying to change my applications activity menu bar title. I managed to change font as follows. Anyone help me to change the name of the title. It may be just a one line, but I can't figure it out.

int actionBarTitle = Resources.getSystem().getIdentifier("action_bar_title", "id", "android");
    TextView actionBarTitleView = (TextView) getWindow().findViewById(actionBarTitle);
    if(actionBarTitleView != null){
        actionBarTitleView.setTypeface(typeFace);
    }

Not sure you can do it your way or not but you can use the bellow solution:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.your_activity);

    final ActionBar actionBar = getActionBar();

    // actionBar
    actionBar.setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);

    // titleTextView
    TextView titleTextView = new TextView(actionBar.getThemedContext());

    titleTextView.setText("Title");
    titleTextView.setTypeface( your_typeface);

    titleTextView.setOtherProperties();

    // Add titleTextView into ActionBar
    actionBar.setCustomView(titleTextView);

}

By doing this solution, you have FULL control of your textview title.