ADDITIONAL SYSTEM INFORMATION :
OS: Fedora release 20 (Heisenbug)
Java: jdk-8u391-linux-x64.tar.gz

A DESCRIPTION OF THE PROBLEM :
font size is more big than normal size (size: 14)

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
You can see the big font size if running my sample code. ( the size of string "-1.718xxx" is greater than 14)


---------- BEGIN SOURCE ----------
public class FontAffineTransformSample extends JPanel {
    static int x3 = 103;
    static int y3 = 200;

    @Override
    public void paint(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;

        /*
         * p2 (100,100)
         * |\
         * | \
         * | \
         * | \
         * p1 p3
         */

        int x2 = 100;
        int y2 = 100;
        int x1 = 100;
        int y1 = 200;
        // int x3 = 105;
        // int y3 = 200;
        g2.drawLine(x1, y1, x2, y2);
        g2.drawLine(FontAffineTransformSample.x3, FontAffineTransformSample.y3,
                x2, y2);
        g2.drawOval(FontAffineTransformSample.x3 - 5,
                FontAffineTransformSample.y3 - 5, 10, 10);

        double agl = FontAffineTransformSample.angle(x1, y1, x2, y2,
                FontAffineTransformSample.x3, FontAffineTransformSample.y3);
        System.out.println(agl);

        AffineTransform fontAF = new AffineTransform();
        fontAF.rotate(Math.toRadians(agl));
        Font newFont = new Font("Dialog", Font.BOLD, 14).deriveFont(fontAF);
        g2.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
                RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
        g2.setFont(newFont);
        g2.drawString(String.valueOf(agl), x2 + 10, y2 - 10);
    }

    public static void main(String[] args) {
        JFrame f = new JFrame();
        FontAffineTransformSample pnl = new FontAffineTransformSample();
        f.add(pnl);
        f.setSize(400, 400);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static double angle(int x1, int y1, int x2, int y2, int x3, int y3) {
        // angle
        double angle12 = Math.atan2(y1 - y2, x1 - x2);
        double angle32 = Math.atan2(y3 - y2, x3 - x2);
        return (angle32 - angle12) * 180.0 / Math.PI;
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Remove code line: g2.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);

FREQUENCY : always