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    <p>You failed to call <code>super.paintComponent(g)</code> inside the overridden <code>paintComponent(...)</code> method. Moreover, while overriding a method of the <code>Base</code> class, always try to keep the access specifier of the methods, the same, as much as possible. In this case it's <code>protected</code> and not <code>public</code> :-) Now function should be like this : </p> <pre><code>@Override protected void paintComponent (Graphics g) { System.err.println("paintComponent()"); super.paintComponent(g); g.fillPolygon(shape); } </code></pre> <h2><strong>EDIT 1 :</strong></h2> <p>Moreover, since you are using a custom shape to be drawn, hence you again failed to specify the <code>ContentAreaFilled</code> property for this <code>JButton</code> in question, hence inside your constructor, you should write <a href="http://docs.oracle.com/javase/7/docs/api/javax/swing/AbstractButton.html#setContentAreaFilled%28boolean%29" rel="nofollow">setContentAreaFilled(false)</a>, for it to work nicely. Though if this doesn't works (for reasons specified in the Docs), then you have to use the plain old <code>Opaque</code> property and set it to <code>false</code> for this <code>JButton</code> using <code>setOpaque(false)</code> :-)</p> <p>Here is your code with modified changes :</p> <pre><code>import java.awt.*; import javax.swing.*; import java.awt.event.*; import javax.swing.event.*; import java.awt.Polygon; public class ShiftingButton extends JButton implements ActionListener { private Polygon shape; public ShiftingButton () { setContentAreaFilled(false); initialize(); addActionListener(this); } protected void initialize() { shape = new Polygon(); setSize(120, 120); shape.addPoint(0, 0); shape.addPoint(0, 60); shape.addPoint(90, 0); } @Override public Dimension getPreferredSize() { return (new Dimension(120, 120)); } // Hit detection public boolean contains(int x, int y) { return shape.contains(x, y); } @Override protected void paintComponent(Graphics g) { System.err.println("paintComponent()"); super.paintComponent(g); g.fillPolygon(shape); } protected void paintBorder(Graphics g) { } @Override public void actionPerformed (ActionEvent ev) { System.out.println("ShiftingButton ActionEvent!"); } public static void main (String[] args) { JFrame frame = new JFrame(); JPanel panel = new JPanel(); ShiftingButton button = new ShiftingButton(); panel.add(button); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.add(panel); frame.pack(); frame.setVisible(true); } } </code></pre>
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    1. CO@Jorocco : No need to call `setSize(120, 120)` even, inside the constructor, I just caught that in your code, I removed the other statements, though missed this one in my code. Since the overridden `getPreferredSize()` will take care of that thingy too :-)
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    2. COThanks! That took care of it. I have one follow-up question though. While it seems like good OO policy to call super.paintComponent(), I'm not sure of its practical significance. That is, if my custom-shaped button exactly defines how the button should look and does not look at all like its superclass, why should it rely on the JButton's painting mechanism? Sorry if this sounds nit-picky, but I just want to understand every line of the code. When I ran it without the super.painComponent() call, I didn't see any difference. Perhaps it would with more elaborate subclassing?
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    3. CO@Jorocco : Please refer to this [answer](http://stackoverflow.com/a/5446768/1057230), the person has explained this in a very nice way. I hope it helps. For the rest you're MOST WELCOME and KEEP SMILING :-)
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