Hi guys,
There is a bug in FormView class which can be best illustrated by the
following test case.
1. First create a JEditorPane that has a "submit" input type in the
"FORM" tag,
JEditorPane html = new JEditorPane("text/html", "<html><body><FORM
ACTION=\"examplescript.cgi\"><INPUT type=\"submit\"
value=\"Submit\"></FORM></BODY></HTML>");
2. And call SwingUtilities.updateComponentTreeUI(html).
3. Now a NPE is thrown when the "submit" button is clicked, which is
apparently a bug.
I filed a sun bug 7189299 to track the bug. A complete runnable Java
test throwing NPE is available in that sun bug. The root cause is that
SwingUtilities.updateComponentTreeUI() triggers FormView instance to
call its member method createInputComponent(AttributeSet attr, Object
model) that instantializes JButton instance. Then, immediately after
the new JButton instance is created, a DefaultButtonModel instance that
is kept in AttributeSet is used to replace innate button model by
calling button.setModel((ButtonModel)model). Tracing into setModel
method, several listeners linking to the new JButton instance are
registered on the shared button model. However, there are no
un-registration calls to remove any previously registered listeners
pertaining to stale JButton instance.
The bug applies to "submit", "reset", "image", "checkbox", "radio"
html types because they call AbstractButton.setModel eventually. But
seems easy to manifest the bug in observable way with only "submit"
type, for example, the NPE above. I wrote another java test in webrev
that asserts number of listeners, which can be applied to all affected
html types.
Please take a look at its patch and test @
http://cr.openjdk.java.net/~youdwei/ojdk-138/webrev.00/
Your comment and effort are highly appreciated.
Best regards,
Frank
