On 11/13/2012 11:53 AM, Frank Ding wrote:
Hi Alexandr,
As for your comment "Could you create an issue that a
JComboBox.setModel(null) call throws NPE? You could fix it before the
7189299 issue. ", I created a bug with internal review ID of 2381499
on JComboBox.setModel(null). But test shows that
JPasswordField.setDocument(null), JTextField.setDocument(null),
JList.setModel(null) and JTextArea.setDocument(null) all throw NPE.
Particularly, JList.setModel(null) has null check and throws
IllegalArgumentException("model" must be non null"). Shall I include
those components as well?
There is the javadoc for the JList setModel() method: Throws
IllegalArgumentException - if model is null. So it is undesirable to
change the public API.
However, it is possible to set a new empty model for the JList. The
list listeners should be removed from the old model in this case.
You could have only 2 issues: one for components that allow to set
a null model but throws NPE (like JComboBox) and another for components
that does not allow to set null model but they do not remove listeners
from the old model in case if a new model is set.
Thanks,
Alexandr.
Thanks for your guidance in advance.
Best regards,
Frank
On 11/8/2012 10:55 PM, Alexander Scherbatiy wrote:
On 11/7/2012 10:56 AM, Frank Ding wrote:
Hi Alexandr,
Unfortunately, all the JComponents involved in
FormView.createComponent() have bugs!
I have done tests for all other swing components, i.e. JCheckBox,
JRadioButton, JPasswordField, JTextField, JList, JComboBox and
JTextField. Sadder news is that if we fix all components in the same
way as I did for JButton, we need to subclass them all, resulting in
JCheckBoxWrapper, JRadioButtonWrapper, JPasswordFieldWrapper,
JTextFieldWrapper, JListWrapper, JComboBoxWrapper, JTextFieldWrapper
plus JButtonWrapper! This approach becomes unacceptable when all
swing components are affected.
Shall we fix it in other way illustrated below?
1. Whenever a swing component is created, it is kept in
AttributeSet, as what is now for model.
2. In FormView.createComponent(), the old swing component can be
retrieved via attr.getAttribute(StyleConstants.ComponentAttribute).
Note that ComponentAttribute is newly added.
This way should be carefully investigated that it does not
introduce new memory leaks.
Could you also check that the StyleConstants.ComponentAttribute
property value can't be rewritten by the JDK code or by public methods.
3. Before setting shared model to a newly initialized swing
component, call oldComp.setModel(null), delegating deregistration to
setModel method.
4. Seems some setModel such as AbstractButton.setModel() can
function well when the param, new model, is null while
JComboBox.setModel() will throw NPE in case of null param.
Could you create an issue that a JComboBox.setModel(null) call
throws NPE? You could fix it before the 7189299 issue.
Thanks,
Alexandr.
5. Add null check code in those problematic setModel or setDocument
methods.
Any idea is appreciated. Thanks.
Best regards,
Frank
On 11/6/2012 9:26 PM, Alexander Scherbatiy wrote:
On 11/5/2012 11:20 AM, Frank Ding wrote:
Hi Alexander,
Based on your comments last time, I refined my patch of v6 and
offered v7 @
http://cr.openjdk.java.net/~dingxmin/7189299/webrev.07/
This version of the fix looks good for me.
It seems that it is the only good way to check that a button
model contains AbstarctButton.Handler listener.
Could you also check that others models used in the
createComponent() method do not have such memory leaks (even the
NPE is not thrown)?
4. Could you add the check that the action listener is invoked
only once after a component tree updating and the action does the
same that it does before a component tree updating?
Answer: I am afraid I could not make it in the auto test
(bug7189299.java) but I can achieve it to some degree in manual
test FormSubmit, the one you illustrated below.
My idea of checking it in FormSubmit.java is subclassing
JEditorPane and overriding 'public EditorKit getEditorKit()' where
stack traces can be examined in the overridden method to make sure
FormView.submitData occurs only once. This approach works because
FormView.submitData() calls JEditorPane.getEditorKit but is
tricky. However, it's the only way I can think of without any
additional framework support. If you are in favor of adding the
check in FormSubmit.java, I am willing to do that.
At least a separated manual test can be added that asks a
user to put a response.html file to a server and according to the
server url checks that JTeditor pane show the response text after a
button pressing.
html = new JEditorPane("text/html",
"<html><body><form action=\"" + userURL + "\">"
+ "<input type=submit name=submit
value=\"submit\"/>"
+ "</form></body></html>");
response.html:
<html> <body> Hello World! </body> </html>
Thanks,
Alexandr.
Thanks again for all your comments and your support. Once
again, if you have any further concern or comment, please don't
hesitate to let me know.
Best regards,
Frank
On 11/1/2012 8:08 PM, Alexander Scherbatiy wrote:
On 11/1/2012 10:35 AM, Frank Ding wrote:
Hi Alexandr,
Thanks for your review. The problem that the JButton does not
release itself as you mentioned is, after taking closer look at
relevant code again, that I removed instance
AbstractButton.Handler as change listener where repainting the
button press animation is defined. So this time I get around
this issue and here comes v6 patch @
http://cr.openjdk.java.net/~dingxmin/7189299/webrev.06/
Below are answers to what you have raised in previous email.
1. if ( if (!listener.equals(this)) { that 'this' means the
JButtonWrapper instead of an action listener.
'this' refers to JButtonWrapper.this because the closest class
definition is JButtonWrapper. I also verified it during my
debugging.
Could you give an example there this check is useful? It
seems that the JButtonWrapper does not implement ActionListener
interface and so the listener and the this always should not be
equal.
I dumped action listeners from the button and model before the
fix and after it.
Before the fix the button has the latest FormView listener and
the model has AbstractButton$Handler added each time after a
component input creation.
After the fix both the button and the model have the FormView
listener and the button does not have the AbstractButton$Handler.
Could you preserve the listeners location and just remove old
listeners from the model?
The fix sets the model to the JButtonWrapper first and than
removes unneccessary listeners from the model. Is it possible to
rearrange order of these operations?
I see that you check number of the listeners in the test.
Could you add the check that the action listener is invoked only
once after a component tree updating and
the action does the same that it does before a component tree
updating.
Thanks,
Alexandr.
2. Why are two FormViews created in this sample?
SwingUtilities.updateComponentTreeUI() triggers html View
hierarchy to update by instantiating new UI instances involved
in the html form. It could have been avoided to have 2 View
instances but we are restricted to current design that LF change
causes creation of View instance which further leads to creation
of new UI instances. Creation of new UI instances upon LF
change can be referenced in BasicTextUI.modelChanged().
3. Why are there 2 listeners added to the button model in this
sample?
The issue is caused by combination of the 2 factors. First, a
shared ButtonModel is created per html Element. Second,
JButton.setModel() automatically registers its private Handler
in the new model but no way to deregister it. The first is a
design choice but the second is a design flaw. Consequence is
that the shared ButtonModel instance bears more and more
JButton.Handler.
I think v6 patch is promising as a final fix. If you have any
further concern or comment, please don't hesitate to let me
know. Thanks again for your careful review.
Best regards,
Frank
On 10/30/2012 9:38 PM, Alexander Scherbatiy wrote:
Hi Frank,
I tried your V5 patch and run the test described in the issue
(see below).
I pressed the button and it does not release. This is because
the AbstractButton.Handler listener is removed because of the fix.
You could check the line
941 if (!listener.equals(this)) {
that 'this' means the JButtonWrapper instead of an action
listener.
Could you also look deeper in the code and say why two
FormViews are created (and each adds it's own listener to the
button model) in this sample?
-----------------------------------------------
import java.awt.*;
import javax.swing.*;
public class FormSubmit {
public static void main(String[] args) throws Exception {
SwingUtilities.invokeAndWait(new Runnable() {
@Override
public void run() {
JEditorPane html = new JEditorPane("text/html",
"<html><body><FORM ACTION=\"examplescript.cgi\"><INPUT
type=\"submit\" value=\"Submit\"></FORM></BODY></HTML>");
JFrame frame = new JFrame()
frame.setLayout(new BorderLayout());
frame.add(html, BorderLayout.CENTER);
frame.setSize(200, 100);
frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
frame.setVisible(true); // Uncomment this line
to see the Exception on JDK 7
SwingUtilities.updateComponentTreeUI(html);
}
});
}
}
-----------------------------------------------
Thanks,
Alexandr.
