RFR: 8240506: TextFieldSkin/Behavior: misbehavior on switching skin

[Marius Hanl]

On Thu, 17 Jun 2021 12:41:56 GMT, Jeanette Winzenburg <fastegal at openjdk.org> wrote:

> The issue is about memory leaks and side-effects (like NPEs) when switching skins. 
> 
> Details (copied from issue for convenience):
> 
> memory leak in TextInputControlBehavior:
> - listener accidentally added twice (removed once)
> - keyPad mappings not properly installed/disposed
> 
> memory leak TextFieldBehavior:
> - listeners to scene/focusOwner property not removed,
> 
> memory leak in TextInputControlSkin:
> - event handlers related to inputMethods not removed
> 
> issues in TextFieldSkin:
> - memory leak due to behavior leaking
> - memory leaks due to manually added change/invalidation listeners that are not removed
> - memory leaks due to not removing children with strong references to skin
> - side-effects (f.i. NPEs) due to listeners/bindings that are still active after dispose
> 
> Fix was to properly install/remove those listeners/handlers. Added tests that failed/passed before/after the fix, respectively, also added tests passing before that must pass after the fix.

Just a formal review, I left some comments inline

modules/javafx.controls/src/main/java/com/sun/javafx/scene/control/behavior/TextFieldBehavior.java line 75:

> 73:         }
> 74: 
> 75:         focusListener = (observable, oldValue, newValue) -> {

Shouldn't this focusListener also be wrapped in a weakListener? Also this lambda expression can be a one-liner (no braces needed)

modules/javafx.controls/src/main/java/javafx/scene/control/skin/TextFieldSkin.java line 389:

> 387:     /** {@inheritDoc} */
> 388:     @Override public void dispose() {
> 389:         if (getSkinnable() == null) return;

Just curious: Can the skinnable be null here? And is it fine then to never call **super.dispose()** ?

modules/javafx.controls/src/main/java/javafx/scene/control/skin/TextFieldSkin.java line 390:

> 388:     @Override public void dispose() {
> 389:         if (getSkinnable() == null) return;
> 390:         getChildren().removeAll(textGroup, handleGroup);

Also curious: Most of the skins don't remove their children in **dispose()**. Are they all wrong, or is this a special case here?

modules/javafx.controls/src/test/java/test/com/sun/javafx/scene/control/behavior/BehaviorCleanupTest.java line 162:

> 160:             secondStage.hide();
> 161:         }
> 162: 

minor: this empty line can be removed

-------------

Changes requested by mhanl (Author).

PR: https://git.openjdk.java.net/jfx/pull/534