Is This a Nimbus Bug?

This code uses Java 6u11 with the Nimbus Look and Feel. I know how to create and apply custom Painters, but I’d rather avoid any com.sun.* dependencies. Those package names will change in Java 7, so I’d rather keep my code “clean”.

Case 1: JButton Background Color

This works:

JButton btn = new JButton("red");
btn.setBackground(Color.RED);

As expected, the button paints with a red background. That’s because deep inside com.sun.java.swing.plaf.nimbus.ButtonPainter, they override getExtendedCacheKeys(JComponent c). In that method, the painter asks the component for its background, on line 398:

if ("background".equals(property)) {
    color = c.getBackground();
}

Case 2: JButtons in a JToolBar

When you put buttons into a JToolBar, setBackground() no longer has any effect. That’s because ToolBarButtonPainter fails to override getExtendedCacheKeys(). ToolBarButtonPainter also has a private array named componentColors like ButtonPainter, but the array is not used.

As I see it, there is no way to set the background color on buttons in a JToolBar without introducing com.sun.* dependencies in our code.

Is this a bug, or a feature? It seems awfully convenient to simply call setBackground(...), even if we’re using Nimbus painters behind the scenes.

Posted on Monday, December 22nd, 2008 at 3:56 pm in Bugs, Java.