RFR: 8241710: NullPointerException while entering empty submenu with "arrow right"

[Jeanette Winzenburg]

On Tue, 7 Apr 2020 07:36:00 GMT, Ajit Ghaisas <aghaisas at openjdk.org> wrote:

> Bug : https://bugs.openjdk.java.net/browse/JDK-8241710
> 
> Root Cause : A menu can have empty submenu. This was not checked while processing RIGHT arrow key.
> 
> Fix : Added the null check for submenu. Added a unit test case which fails without fix and passes with it.

Verified the fix: test is failing before and passing after.

See one inline comment (just noting my personal pref :).

And again me fighting the system (can't seem to review code parts that are not near a change, so doing here:

- copyright year doesn't seem to be updated
- there's another fishy looking code line in MenuItemContainer actionHandler:

      actionEventHandler = e -> {
           if (item instanceof Menu) {
                 final Menu menu = (Menu) item;
                 if (openSubmenu == menu && submenu.isShowing()) return;
 
don't know when/if that's ever reached (could get there - an action handler on the region itself?), anyway, at other
places with a similar pattern (f.i processRightKey) there's an explicit guard against a null submenu, don't know if the
latter is over-caution - logic and code is rather .. well .. inter-twined ;)

modules/javafx.controls/src/main/java/com/sun/javafx/scene/control/ContextMenuContent.java line 658:

> 657:             ContextMenuContent cmContent = (ContextMenuContent)submenu.getSkin().getNode();
> 658:             if (cmContent != null) {
> 659:                if (cmContent.itemsContainer.getChildren().size() > 0) {

just a mini-note: personally, I prefer early-return on no-match (vs. wrapping nearly the whole method inside an if match

    if (submenu == null) return;

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PR: https://git.openjdk.java.net/jfx/pull/161