Problem with overridding JButton paintComponent

Question

I have written an extension of JButton that simply paints an octagon on the button:
package myPackage;
import javax.swing.JButton;
import javax.swing.JPanel;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Polygon;
import javax.swing.JFrame;
import java.io.Serializable;
public class MyButton extends JButton implements Serializable {
public MyButton() {
super();
public void paintComponent(Graphics g) {
super.paintComponent(g);
int[] xPoints = new int[9];
int[] yPoints = new int[9];
int endX, beginX, endY, beginY;
super.paintComponent(g);
int w = getSize().width;
int h = getSize().height;
// get the smaller of the two
int min = (w > h ? h : w);
System.out.println(w + ", " + h + ", " + min + ", " + getLocation());
beginX = getLocation().x + (w - min) / 2;
endX = beginX + min;
beginY = getLocation().y + (h - min) / 2;
endY = beginY + min;
System.out.println(beginX + ", " + beginY + ", " + endX + ", " + endY);
// Set the proper points to draw a 8 sided polygon
// These formulas are based on where a point should be
// proportionally relitive to the starting point (x1,y1)
// and the ending point (x,y)
xPoints[0] = (endX - beginX) / 4 + beginX;
xPoints[1] = (endX - beginX) * 3 / 4 + beginX;
xPoints[2] = endX;
xPoints[3] = endX;
xPoints[4] = (endX - beginX) * 3 / 4 + beginX;
xPoints[5] = (endX - beginX) / 4 + beginX;
xPoints[6] = beginX;
xPoints[7] = beginX;
xPoints[8] = (endX - beginX) / 4 + beginX;
yPoints[0] = beginY;
yPoints[1] = beginY;
yPoints[2] = (endY - beginY) / 4 + beginY;
yPoints[3] = (endY - beginY) * 3 / 4 + beginY;
yPoints[4] = endY;
yPoints[5] = endY;
yPoints[6] = (endY - beginY) * 3 / 4 + beginY;
yPoints[7] = (endY - beginY) / 4 + beginY;
yPoints[8] = beginY;
Polygon p = new Polygon(xPoints, yPoints, 8);
g.setColor(Color.RED);
g.fillPolygon(p);
public static void main(String args[]) {
JFrame jf = new JFrame("Stop Button");
// change false to true to see it in a JPanel
if (false) {
JPanel jp = new JPanel();
jp.setLayout(new BorderLayout());
jp.add(new MyButton(), BorderLayout.NORTH);
jf.add(jp);
} else {
jf.add(new MyButton());
jf.setSize(new Dimension(100, 100));
jf.setVisible(true);
This works fine ... until I reference it from a larger program. I used Netbeans 6.1 GUI builder for a more complicated structure. When I run the larger app ... the button is blank. Here's the main part of the code that the builder generated:
javax.swing.GroupLayout topPanelLayout = new javax.swing.GroupLayout(topPanel);
topPanel.setLayout(topPanelLayout);
topPanelLayout.setHorizontalGroup(
topPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(topPanelLayout.createSequentialGroup()
.addContainerGap()
.addGroup(topPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addGroup(topPanelLayout.createSequentialGroup()
.addComponent(stopButton, javax.swing.GroupLayout.PREFERRED_SIZE, 24, javax.swing.GroupLayout.PREFERRED_SIZE)) <---------------------
.addComponent(tickerField))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(srButton)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(channelButton)
.addGap(14, 14, 14)
.addComponent(measurementPanel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addContainerGap())
I'm using JDK 1.6, and don't have a lot of experience chasing down Swing problems. Could you please make some suggestions as to what I'm doing wrong?? The print statements show me that the paintComponent method is being reached when I move the mouse over the button, but nothing gets drawn!!!
Thanks in advance for any help you can provide.
Dwight

Answer 1

Here's some of your code,
if (false) {
      JPanel jp = new JPanel();
      jp.setLayout(new BorderLayout());
      jp.add(new MyButton(), BorderLayout.NORTH);
      jf.add(jp);
} else {
     jf.add(new MyButton());
jf.setSize(new Dimension(100, 100));In both cases your button is being added to a container using BorderLayout. When the container resizes so to does the button. That's why this works,
public MyButton() {
     super();
public void paintComponent(Graphics g) {
     int w = getSize().width;
     int h = getSize().height;
}Initially MyButton has zero size, but when the frame's size is set the BorderLayout will change the size of MyButton.
However, with a more complicated GUI and GroupLayout the button may not necessarily change size when the frame's size is set. It may remain at its preferred size - which is zero or close to it (since it has no text or icon). So now all of a sudden getWidth() and getHeight() return zero (or close to it). You need to set an appropriate preferred size
public MyButton() {
     super();
     setPreferredSize(...);  //<--- add a line like this
}