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J/X/Tree: expanding all nodes on a large tree on/off EDT?

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Joined: 2003-06-11
Points: 0

Posted at OTN

copied here for your convenience:

recently I was remembered of a long-standing task in SwingX, which is to support expanding all nodes of a JXTree .. for large trees.

JXTree has api to do so, with a naive implemenation which simply loops through all rows until the end. That's good enough for smaller trees, but not for larger, can take minutes and is blocking the EDT.

Simple way is to tell the developer it's no good for larger trees, "your job to do it somehow in the background" ---  thinking about it, I couldn't come up with any idea about the how-to: expanding _is_ all ui-related touching several view-related classes including the tree itself during expansion, so looks like it has to happen on the EDT. Being so, the next option might be some way to partion the expansion into smaller chunks, each being so small that the effective blocking wouldn't be noticeable with some prioritizing such that the visible part of the tree always is expanded. Sounds like quite a task ..

On the other hand, maybe an ui which allows expanding 100k of nodes at once isn't optimal anyway - considering the time it would take the user to browse 100k nodes .. if so, SwingX could lean back and do nothing, happy option :-)

Opinions, ideas, references to existing code or discussions highly welcome!



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Joined: 2006-06-08
Points: 0


As noted elsewhere, chunking could help.  A simple Swing Timer that performs a batch of expansions would be fine.  It need checks for ensuring that the model didn't change or some other interrupt (collapse all, etc.) didn't happen.  A nice wait cursor would help during this period.

We also may be able to speed up the process in several ways:

  1. expandAll calls expandRow.  I think this is a hog (gut feel, no profiling).  We already have access to the model.  Why not access it directly, building our own TreePaths to call into setExpandedState?
  2. Chunking approaches
    1. Batch in order.
    2. Walk outward birectionally from the visible rows.


Joined: 2003-06-11
Points: 0


all good points :-)

With the feedback from OTN, it looks like this is a bigger task than I thought it would be - so created a feature issue

... and keeping up thinking (and re-learning about tree traversals - which I always hated ;-).

Thanks, Jeanette



Joined: 2011-03-29
Points: 0


Unfortunately I got no solution for the problem, but I am interested in a solution ;)

At the moment as I wrote on the threads below I am working on a File-System-Treetable and it is not unusual, that

you got more then 100000 files on a default system.