How to assign text size in sp value using java code

http://developer.android.com/reference/android/widget/TextView.html#setTextSize%28int,%20float%29

Example:

textView.setTextSize(TypedValue.COMPLEX_UNIT_SP, 65);

Cleaner and more reusable approach is

define text size in dimens.xml file inside res/values/ directory:

</resources>
   <dimen name="text_medium">14sp</dimen>
</resources>

and then apply it to the TextView:

textView.setTextSize(TypedValue.COMPLEX_UNIT_PX, context.getResources().getDimension(R.dimen.text_medium));

You can use a DisplayMetrics object to help convert between pixels and scaled pixels with the scaledDensity attribute.

DisplayMetrics dm = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(dm);
pixelSize = (int)scaledPixelSize * dm.scaledDensity;