Android text-size programmatically too big

Question

I have two szenarios:

First:

 textView.setTextSize(getResources().getDimension(R.dimen.defaultTextSize));

Second in xml:

android:textSize="@dimen/defaultTextSize"

in values/dimen.xml i have declared defaultTextSize with 20sp

In my first case the text is much bigger (and different in some screenresulutions) than in my second case. Why? Have I done a mistake?

Answer 1

setTextSize() takes unit as pixel

Use this

public float pixelsToSp(float px) 
{
    float scaledDensity = _context.getResources().getDisplayMetrics().scaledDensity;
    return px/scaledDensity;
}

textView.setTextSize(pixelsToSp(getResources().getDimension(R.dimen.defaultTextSize)));

or

textView.setTextSize(TypedValue.COMPLEX_UNIT_PX, getResources().getDimension(R.dimen.defaultTextSize))