How to change tab text color dynamically from coding end.

[Sorwar-Hosen-Mostafa]

I tried to set it by,
tab.setDefaultTabTextColor(R.color.primary_color);
its not working.
i have also tried adding.
tab.invalidate();
its not working either.

And last but not the least,
also how to set selector color drawables as default color dynamically..

i need to change the selected tab text color according to the tab background. unselected tab colors can be default.