code: @Override
     public Typeface  resolveFont(String fontFamily, int fontWeight, String fontStyle)
     {
        Log.i(TAG, "resolveFont("+fontFamily+","+fontWeight+","+fontStyle+")");
  
        // Try font name with suffix ".ttf"
        try
        {
           return Typeface.createFromAsset(assetManager, fontFamily + ".ttf");
        }
        catch (RuntimeException ignored) {}
  
        // That failed, so try ".otf"
        try
        {
           return Typeface.createFromAsset(assetManager, fontFamily + ".otf");
        }
        catch (RuntimeException e)
        {
           return null;
        }
     }
docs: Attempt to find the specified font in the "assets" folder and return a Typeface object.
  For the font name "Foo", first the file "Foo.ttf" will be tried and if that fails, "Foo.otf".