Use of overriding getPreferredSize() instead of using setPreferredSize() for fixed size Components

I read some posts here and I started why some people do

@Override
public Dimension getPreferredSize() {
    return new Dimension(500, 500);
}

instead of

setPreferredSize(new Dimension(500, 500));

Isn't the second one better because it creates only one Dimension object whereas the first one possibly creates several (even if it's not that much wasted memory)? Or am I wrong? Is there a difference at all?