CODEWITHSUNDEEP
swteclipse-rcprcptreeviewer
Srikant Barik
Srikant Barik

Reputation: 153

How to retain the state of a treeviewer in Java RCP application?

I have a simple RCP application having couple of wizards out of which one is having a tree viewer. I want to retain the state of the selected item in the tree viewer next time I open that particular view. As of now I have implemented using static variables and its working fine.I want to know how it can be done in a better way?

//Sample Code

private static RepositoryLocationItem lastRepoItemSelected;

Composite parent=new Composite(SWT.NONE)
treeViewer = new TreeViewer(parent);
treeViewer.setContentProvider(new MovingBoxContentProvider());
treeViewer.setLabelProvider(new MovingBoxLabelProvider());
treeViewer.setInput(getInitalInput());

treeViewer.addSelectionChangedListener(new ISelectionChangedListener() {

/* Setting the value of lastRepoItemSelected */
});


if(lastRepoItemSelected !=null)
{
treeViewer.setSelection(new StructuredSelection(lastRepoItemSelected),true); 
}

Upvotes: 0

Views: 241

Answers (1)

greg-449
greg-449

Reputation: 111217

Assuming this is a 3.x style RCP (your view extends ViewPart) you can use the saveState method to save your view state:

@Override
public void saveState(final IMemento memento)
{
  // TODO set values in the 'memento'
}

You can then use the init method to restore values from the memento when the view is shown again:

@Override
public void init(final IViewSite site, final IMemento memento)
  throws PartInitException
{
  super.init(site, memento);

  // TODO restore from 'memento'
}

Note: Mementos are persisted across restarts of your RCP so you need to store values in them which are valid in a new instance of the RCP.

Also look at the Eclipse wiki entry for more information.

For a WizardPage you can use the IDialogSettings. You must set this up in your Wizard using something like:

IDialogSettings pluginSettings = Activator.getDefault().getDialogSettings();
IDialogSettings wizardSettings = pluginSettings.getSection("id of your wizard");
if (wizardSettings == null) {
    wizardSettings= new DialogSettings("id of your wizard");
    pluginSettings.addSection(wizardSettings);
}
setDialogSettings(wizardSettings);

where Activator is your plugin activator class and "name of your wizard" is a id for your wizard (which can be anything as long as it is unique in your plugin).

In your wizard page you can then get the settings with:

IDialogSettings settings = getDialogSettings();

IDialogSettings has lots of methods for saving and restore various sorts of values, such as:

settings.put("key", "string value");

String value = settings.get("key");

Upvotes: 4

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