code: public void setXY(int index, double x, double y) {
  		if (index < 0 || index >= m_pointCount)
  			// TODO exc
  			throw new IndexOutOfBoundsException();
  
  		_verifyAllStreams();
  		// AttributeStreamOfDbl v = (AttributeStreamOfDbl)
  		// m_vertexAttributes[0];
  		// TODO ask sergey about casts
  		AttributeStreamOfDbl v = (AttributeStreamOfDbl) m_vertexAttributes[0];
  		v.write(index * 2, x);
  		v.write(index * 2 + 1, y);
  		notifyModified(DirtyFlags.DirtyCoordinates);
  	}
docs: Checked vs. Jan 11, 2011