Integrated: 8294809: ListenerHelper for managing and disconnecting listeners

[Andy Goryachev]

On Fri, 7 Oct 2022 20:50:55 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

> Introduction
> 
> There is a number of places where various listeners (strong as well as weak) are added, to be later disconnected in one go. For example, Skin implementations use dispose() method to clean up the listeners installed in the corresponding Control (sometimes using LambdaMultiplePropertyChangeListenerHandler class).
> 
> This pattern is also used by app developers, but there is no public utility class to do that, so every one must invent their own, see for instance
> https://github.com/andy-goryachev/FxTextEditor/blob/master/src/goryachev/fx/FxDisconnector.java
> 
> Proposal
> 
> It might be beneficial to create a class (ListenerHelper, feel free to suggest a better name) which:
> 
> - provides convenient methods like addChangeListener, addInvalidationListener, addWeakChangeListener, etc.
> - keeps track of the listeners and the corresponding ObservableValues
> - provides a single disconnect() method to remove all the listeners in one go.
> - optionally, it should be possible to add a lambda (Runnable) to a group of properties
> - optionally, there should be a boolean flag to fire the lambda immediately
> - strongly suggest implementing an IDisconnectable functional interface with a single disconnect() method
> 
> Make it Public Later
> 
> Initially, I think we could place the new class in package com.sun.javafx.scene.control; to be made publicly accessible later.
> 
> Where It Will Be Useful
> 
> [JDK-8294589](https://bugs.openjdk.org/browse/JDK-8294589) "MenuBarSkin: memory leak when changing skin"
> and other skins, as a replacement for LambdaMultiplePropertyChangeListenerHandler.
> 
> https://github.com/openjdk/jfx/pull/908#:~:text=19%20hours%20ago-,8295175%3A%20SplitPaneSkinSkin%3A%20memory%20leak%20when%20changing%20skin%20%23911,-Draft
> 
> https://github.com/openjdk/jfx/pull/914

This pull request has now been integrated.

Changeset: 3376228a
Author:    Andy Goryachev <angorya at openjdk.org>
Committer: Kevin Rushforth <kcr at openjdk.org>
URL:       https://git.openjdk.org/jfx/commit/3376228afa0692073d99680558e09bed9c5bfa89
Stats:     1044 lines in 4 files changed: 1040 ins; 2 del; 2 mod

8294809: ListenerHelper for managing and disconnecting listeners

Reviewed-by: kcr, aghaisas

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PR: https://git.openjdk.org/jfx/pull/908