[hardwired]

Code:

Point point2 = new Point(100,200);

protected void paintComponent(Graphics g) {
    Graphics2D graphics2D = (Graphics2D)g;
    AffineTransform at =
        AffineTransform.getTranslateInstance(point2.x, point2.y);
    int b = 8;
    double theta = Math.toRadians(45);
    // The idea of using a GeneralPath is so we can
    // create the (three lines that make up the) arrow
    // (only) one time and then use AffineTransform to
    // place it anywhere we want.
    GeneralPath path = new GeneralPath();

    // Add the arrow shaft.
    path.moveTo(0,0);
    path.lineTo(-100,0);

    // distance between line and the arrow mark  <** not **
    // Start a new line segment from the position of (0,0).
    path.moveTo(0,0);
    // Create one of the two arrow head lines.
    int x =(int)(-b * Math.cos(theta));
    int y =(int) (b * Math.sin(theta));
    path.lineTo(x,y);

    // distance between line and the arrow mark  <** not **
    // Make the other arrow head line.
    x = (int) (-b * Math.cos(-theta));
    y = (int) (b * Math.sin(-theta));                
    path.moveTo(0,0);
    path.lineTo(x,y);

    // theta was used for the angle between the arrow
    // shaft and each of its arrow head lines.
    // If you wnat to also rotate the arrow (GeneralPath)
    // by 45 degrees, okay.
    // Set up the transform the way you want it, ie, do
    // all the work before drawing the final result.
    at.rotate(theta,x,y);
    Shape shape = at.createTransformedShape(path);
    graphics2D.setPaint(Color.black);
    graphics2D.draw(shape);

    // This is unnecessary since you are using the
    // GeneralPath to store all three lines segments
    // that make up the arrow, ie, the GeneralPath is
    // the arrow. So you apply the AffineTransform to
    // the GeneralPath and it does all the work.
    // line drawing 2 points.
//    graphics2D.drawLine(point2.x,point2.y,point4.x,point4.y);
}