How do I add a line (graphic) as a Component to a JPanel

Question

I'm using swing, and the line-component should be used in the JPanel with plenty of buttons. Therefor it is important that it is as small as possible, with no large background.

Answer 1

The line is just a line from x1,x2 to y1,y2.
The point is that I do not want to use drawLine(), i preferable want to use setBounds, so that I can just add the component to the contentPane like a Jbutton.
I want my class to be a variant of something like this:
public class Line extends JComponent {
int x1,x2,y1,y2;
public Line(int X1,int X2,int Y1,int Y2) {
x1 = X1;
x2 = X2;
y1 = Y1;
y2 = Y2;
public void paint(Graphics g){
super.paintComponent(g);
//g.setColor(Color.white);
//g.fillRect(0,0,getWidth(),getHeight());
// g.drawLine(x1,x2,y1,y2);
}