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TreeViewer refresh() collapse problem-- SWT [message #528054]

Mon, 19 April 2010 02:49

Prasad
Messages: 8
Registered: April 2010

Junior Member

Hi all,
I am calling refresh() method on SWT TreeViewer object..all the previously expanded items are getting collapsed..
I want to have the previous state of tree after i call refresh() method...

How to do this.. any suggestions please...

Thanks,
Prasad.

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Re: TreeViewer refresh() collapse problem-- SWT [message #528066 is a reply to message #528054]

Mon, 19 April 2010 03:57

Thomas Schindl
Messages: 4462
Registered: July 2009

Senior Member

You need to:
a) make your object implement equals/hashcode
b) implement an IElementComparer

Tom

Am 19.04.10 08:49, schrieb Prasad:
> Hi all,
> I am calling refresh() method on SWT TreeViewer object..all the
> previously expanded items are getting collapsed..
> I want to have the previous state of tree after i call refresh() method...
> How to do this.. any suggestions please...
>
> Thanks,
> Prasad.

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Re: TreeViewer refresh() collapse problem-- SWT [message #528084 is a reply to message #528066]

Mon, 19 April 2010 05:46

Prasad
Messages: 8
Registered: April 2010

Junior Member

Hi Tom,
I did not get you...

Can you please explain me in detail...

Thanks,
Prasad.

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Re: TreeViewer refresh() collapse problem-- SWT [message #733541 is a reply to message #528084]

Tue, 04 October 2011 21:28

Jay Mising name
Messages: 9
Registered: August 2011

Junior Member

The Treeviewer needs to be able to consider if your elements are equal to one another. You should implement hashcode() and equals() based on some field or method in your class that identifies it's uniqueness.

In Eclipse you can say : Source->Generate hashcode & equals. It will then ask you what fields you want to use to compare uniqueness, but I just replaced them with my toString() method.

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result
				+ ((toString() == null) ? 0 : toString().hashCode());
		return result;
	}



	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		UConfiguration other = (UConfiguration) obj;
		if (toString() == null) {
			if (other.toString() != null)
				return false;
		} else if (!toString().equals(other.toString()))
			return false;
		return true;
	}

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Re: TreeViewer refresh() collapse problem-- SWT [message #733578 is a reply to message #733541]

Wed, 05 October 2011 02:12

Thomas Schindl
Messages: 4462
Registered: July 2009

Senior Member

it is much better to set an IElementComparer on to the viewer.

Tom
Am 05.10.11 03:28, schrieb Jay:
> The Treeviewer needs to be able to consider if your elements are equal
> to one another. You should implement hashcode() and equals() based on
> some field or method in your class that identifies it's uniqueness.
> In Eclipse you can say : Source->Generate hashcode & equals. It will
> then ask you what fields you want to use to compare uniqueness, but I
> just replaced them with my toString() method.
>
>
> @Override
> public int hashCode() {
> final int prime = 31;
> int result = 1;
> result = prime * result
> + ((toString() == null) ? 0 : toString().hashCode());
> return result;
> }
>
>
>
> @Override
> public boolean equals(Object obj) {
> if (this == obj)
> return true;
> if (obj == null)
> return false;
> if (getClass() != obj.getClass())
> return false;
> UConfiguration other = (UConfiguration) obj;
> if (toString() == null) {
> if (other.toString() != null)
> return false;
> } else if (!toString().equals(other.toString()))
> return false;
> return true;
> }
>

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