Docs for Binding lacking?

Jonathan Giles jonathan.giles at
Thu Jun 13 16:53:19 PDT 2013

I'm not involved in the development of the binding API, so I'll leave a 
full response to the professionals, but you may be interested in this 
jira that was just resolved yesterday by Martin:

-- Jonathan

On 14/06/2013 11:41 a.m., John Hendrikx wrote:
> Hi List,
> I'm having a hard time to find good documentation on some aspects of 
> bind and bindDirectional.  I found several forum posts, some books and 
> lots of examples, but none really touch upon the subject of references 
> between bindings and garbage collection.
> Would it be possible to enhance the javadocs a bit or create a 
> tutorial for this?  Things that are unclear for me (until I test by 
> trail and error), so correct me if I got something wrong:
> 1) Garbage collection of bindings; basically, X.bind(Y) will result in 
> X's lifecycle to be bound to Y.  If Y is a long-lived object, and X is 
> a short-lived frequently replaced object, then many instances of X 
> will be left around consuming memory (and CPU cycles on every Y 
> update) until Y dies.  A single forgotten binding of this type can 
> result in whole UI graphs to be locked in memory.
> The same does not occur with bindBidirectional. The javadocs describe 
> this type of binding as "bind with inverse", which sounds to me it is 
> mere short-hand for doing X.bind(Y) + Y.bind(X), if that were allowed, 
> resulting in both X and Y's lifecycles to be bound to each other.  
> Yet, that's not what happens.  With a bidirectional binding, either X 
> or Y can go out of scope, and the binding dies with it, which is a 
> very nice feature and an important consideration when choosing the 
> type of binding that it deserves some mention in the docs.
> Using bind() seems to be the default that is used everywhere, because 
> it is short and nice -- I'm however thinking my life would have been 
> much easier had I used bindBidirectional as the "default" binding 
> everywhere in my code -- I'm pretty sure most of the bindings I did in 
> the past could have been bidirectional without any consequence. In 
> complex cases with many unidirectional bindings (that maybe could have 
> been bidirectional without impacting the result), I resorted to using 
> a helper class that keeps track of all the bindings created so they 
> can all be unbound with a single call to avoid creating somekind of 
> memory leak.
> 2) For bi directional bindings, it is unclear which value will be the 
> final result of the two bound properties (especially confusing in 
> Bindings.bindBidirectional).  X.bind(Y) will mean X takes the value of 
> Y as the direction of the binding enforces it. X.bindBidirectional(Y) 
> or Bindings.bindBidirectional(X, Y) have no direction and it is 
> unclear whether, initially, the result will be the value of X or the 
> value of Y.
> --John

More information about the openjfx-dev mailing list