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TreeViewer refresh [message #547302]

Fri, 16 July 2010 09:08

Philipp Schill

Messages: 11
Registered: July 2010

Junior Member

Hello all,
i have a problem with a treeviewer.
My problem is, when I call treeviewer.refresh() my tree collapses until the first level, e.g.

original state before rerfesh:

Customer
--- Project A
------ Folder AA
--------- File AA
--------- File AB
--- Project B
------Folder BA
--------- File BA
--------- File BB

after calling refresh, my tree looks like:

Customer
--- Project A
--- Project B

(collapsed to the first level).

Does anyone have any hints what to do to fix this problem?

Environment:
Eclipse Build id: 20100218-1602
WinXP

Thanks and regards!

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Re: TreeViewer refresh [message #547450 is a reply to message #547302]

Fri, 16 July 2010 21:27

budili Missing name

Messages: 64
Registered: May 2010

Member

If you want to expand all items, after refresh the viewer,
then use the simpel method expand:

treeViewer.expandAll();

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Re: TreeViewer refresh [message #547534 is a reply to message #547302]

Sun, 18 July 2010 14:03

Philipp Schill

Messages: 11
Registered: July 2010

Junior Member

No, I only want to get my tree like before the refresh.

So my question is still, what do I have to do, or wahts wrong with my implementation, when my tree collapses to the first level?

Thanks!

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Re: TreeViewer refresh [message #547539 is a reply to message #547534]

Sun, 18 July 2010 15:15

Thomas Schindl

Messages: 6651
Registered: July 2009

Senior Member

Implement an IElementComparer
Am 18.07.10 16:03, schrieb Philipp Schill:
> No, I only want to get my tree like before the refresh.
>
> So my question is still, what do I have to do, or wahts wrong with my
> implementation, when my tree collapses to the first level?
>
> Thanks!

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Re: TreeViewer refresh [message #548098 is a reply to message #547539]

Tue, 20 July 2010 16:15

Mark Storer

Messages: 46
Registered: May 2010
Location: Vista, CA

Member

Tom Schindl wrote on Sun, 18 July 2010 08:15

Implement an IElementComparer

So what do equals and hashCode have to do with the tree being open or closed?

A guess: Refresh recreates the tree such that it is "equal". If the new equal/hash function that includes the nodes "open-ness" will force refesh() to preserve the tree's state.

(and presumably the root node is a special case that already handles this... which makes me wonder why the default tree node doesn't as well.)

--Mark Storer
Senior Software Engineer
Autonomy Cardiff

import legalese.disclaimer;
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[Updated on: Tue, 20 July 2010 16:21]

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Re: TreeViewer refresh [message #548105 is a reply to message #548098]

Tue, 20 July 2010 16:28

Thomas Schindl

Messages: 6651
Registered: July 2009

Senior Member

Most of the time when people do a refresh they recreat the underlying
model data.

For a TreeViewer a refresh means to completely recreate itself
(=Disposing/recreating TreeItems - there's some optimization code to not
dispose all but it's easier to understand this way) which means they all
loose their state but before doing so it remembers the open TreePaths
(Domain-Object-List) and tries to restore the state after the refresh.

The problem is that if you have created new object instances how should
the viewer know which object corresponds to each other.

There are now 2 solutions:
a) Overload equals/hashCode in your domain code
b) Set an IElementComparer to assist the Viewer code to find logically
equal objects

Tom

Am 20.07.10 18:15, schrieb Mark Storer:
> Tom Schindl wrote on Sun, 18 July 2010 08:15
>> Implement an IElementComparer
>
>
> So what do equals and hashCode have to do with the tree being open or
> closed?
>
> A guess: Refresh recreates the tree such that it is "equal". If the
> new equal/hash state includes the nodes "open-ness" then the tree will
> be preserved when its refreshed.
>
>
>

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