If you apply "no border" to a JTable inside a JScrollPane Netbeans will setBorder(null) and you will notice the border does not get removed. Using EmptyBorder(0, 0, 0, 0) works just fine.

I don't agree with that. Usage of empty border to enforce no border is a workaround for some special/problematic situations and it should not be the default approach.

In fact, it is just an implementation detail that setting of null border doesn't work in the mentioned case while setting of empty border works.

The official documention (of JComponent.setBorder()) says:

"Although technically you can set the border on any object that inherits from JComponent, the look and feel implementation of many standard Swing components doesn't work well with user-set borders. In general, when you want to set a border on a standard Swing component other than JPanel or JLabel, we recommend that you put the component in a JPanel and set the border on the JPanel."

Hence, there is no guarantee that even empty border will not be overriden for component different from JLabel and JPanel. On the other hand, for the only components for which this method is guaranteed to work (JLabel and JPanel) it is perfectly fine to use null.

Jan,

My interpretation of "doesn't work well" in "[...] the look and feel implementation of many standard Swing components doesn't work well with user-set borders" is that it won't look nice. I am not aware of any L&F implementation that overrides an empty border. Are you?

On the other hand, http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4143601 specifically states that setBorder(null) *is* meant to be overridden by L&Fs.

You could be perfectly right about empty borders being overridden, but we should have concrete proof of this. Can you perhaps ask someone in the Swing team for a clarification?

*** Bug 194927 has been marked as a duplicate of this bug. ***

Reopening this issue.

1. Jan's interpretation disagrees with the BugParade evaluation which reads:

"L&Fs are only allowed to remove/replace borders and colors which meet one of two criteria.  If they are set to null, or if the instance returned from the "get" method implements the UIResource interface."

Please request feedback/clarification from additional sources (ideally from the Swing team).

2. Regardless of which interpretation is right, the fact of the matter is that Netbeans does the wrong thing when the user sets a border on a JTable inside a JScrollPane. This should be fixed.

The "right thing" would be to allow users to set the border in the visual editor and do whatever is necessary under-the-hood for it to look right. The current behavior is pushing implementation details on end-users.