[jira] [Commented] (PIVOT-751) TabPaneSelectionListener#selectedIndexChanged called twice when first tab is inserted

["Chris Bartlett (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PIVOT-751?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13065717#comment-13065717 ] 

Chris Bartlett commented on PIVOT-751:
--------------------------------------

Does anyone have any comments on this?

According to the javadocs, the previousSelectedIndex value of the selectedIndexChanged event will represent the previously selected index or the currently selected index depending on whether the change was direct/indirect.
http://pivot.apache.org/2.0/docs/api/org/apache/pivot/wtk/TabPaneSelectionListener.html#selectedIndexChanged(org.apache.pivot.wtk.TabPane, int)

I feel that a single event should be fired as there is only actually one change of the selected index value, but am not sure which of the two it should be.  My initial thought was that it should be the first event, but after reading the javadoc, think it should be the second one.


The first event that is currently fired has a previousSelectedIndex value of -1.  This is the actual previous selection index value, and according to the javadocs, should arise from a direct/explicit selection change.

The second event that is currently fired has a previousSelectedIndex value of 0.  This is the current selection index value, and according to the javadocs, should arise from an indirect selection change.  That certainly seems to describe this scenario as no explicit selection change was made, rather a new tab was added.

So perhaps it should actually be the first event that is suppressed rather than the second one?

> TabPaneSelectionListener#selectedIndexChanged called twice when first tab is inserted
> -------------------------------------------------------------------------------------
>
>                 Key: PIVOT-751
>                 URL: https://issues.apache.org/jira/browse/PIVOT-751
>             Project: Pivot
>          Issue Type: Bug
>          Components: wtk
>    Affects Versions: 2.0
>            Reporter: Edvin Syse
>            Priority: Minor
>             Fix For: 2.0.1
>
>
> If you add a tab to an _empty_ tabpane, two selectedIndexChanged events are called. I.e, when you add a TabPaneSelectionListener to a tabpane and call:
> tabpane.getTabs().add(component);
> .. the listener fires twice, with previousSelectedIndex set to -1 and then 0.
> The two events are fired by line 68 and 72 in TabPane.java:
> 68            tabPaneListeners.tabInserted(TabPane.this, index);
> 69
> 70            // Fire selection change event, if necessary
> 71            if (selectedIndex != previousSelectedIndex) {
> 72 tabPaneSelectionListeners.selectedIndexChanged(TabPane.this, selectedIndex);
> 73            }
> This could be fixed by taking into account that previousSelectedIndex might have been -1 when invoked, like this:
> if (selectedIndex != previousSelectedIndex && previousSelectedIndex > -1) { 
> See this thread for more info: http://apache-pivot-users.399431.n3.nabble.com/TabPaneSelectionListener-selectedIndexChanged-called-twice-when-first-tab-is-inserted-td3022515.html
> PS: According to Chris, CardPane and Accordion behave in the same way, so any changes to TabPane should also be made to these for consistency.

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