Text width/height

How do I find out the size of rendered text?

Specifically, I want to draw text in the middle of a JPanel. Something like this:

    public void paint (Graphics g)
    {
        int x = getWidth()/2 - getTextWidth ("String")/2;
        int y = getHeight()/2 - getTextHeight ("String")/2;
        g.drawString ("String", x, y);
    }

Except, of course, that getTextWidth and getTextHeight don't exist, so what do I need to use?