It's possible that your TextView isn't measured yet.
With a ViewTreeObserver you can be notify when your TextView is rendered, then you can have it's height :
ViewTreeObserver vto = v.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
if (v != null && getActivity() != null) {
ViewTreeObserver obs = v.getViewTreeObserver();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
obs.removeOnGlobalLayoutListener(this);
} else {
obs.removeGlobalOnLayoutListener(this);
}
int i = v.getHeight();
}
}
});