Eclipse JFace's Wizards

Question

I need a wizard which second page content depends on the first page's selection. The first page asks the user the "kind" of filter he wants to create and the second one asks the user to create one filter instance of the selected "kind".

JFace's wizards pages contents (createControl(...) method) are all created when the wizard is open and not when a given page is displayed (this allow JFace to know the wizard size I guess ??).

Because of this, I have to create my second page content BEFORE the wizard is opened BUT I can't since the second page's content depends on the first page selection.

For now the cleaner solution I found consists in creating all (seconds) pages before the wizard is open (with their content) and override the getNextPage() method in the first page's implementation.

The main drawback of that solution is that it can be be expensive when there are many second pages to create.

What do you think about that solution ? How do you manage your wizard's pages ? Is there any cleaner solution I missed ?

Answer 1

The approach is right if you are several other pages which are

• completely different one with another
• depends on the previous choices made in a previous page

Then you can add the next page dynamically (also as described here)

But if you have just a next page with a dynamic content, you should be able to create that content in the onEnterPage() method

public void createControl(Composite parent)
{
    //
    // create the composite to hold the widgets
    //
    this.composite = new Composite(parent, SWT.NONE);

    //
    // create the desired layout for this wizard page
    //
    GridLayout layout = new GridLayout();
    layout.numColumns = 4;
    this.composite.setLayout(layout);

    // set the composite as the control for this page
    setControl(this.composite);
}

void onEnterPage()
{
    final MacroModel model = ((MacroWizard) getWizard()).model;
    String selectedKey = model.selectedKey;
    String[] attrs = (String[]) model.macroMap.get(selectedKey);

    for (int i = 0; i < attrs.length; i++)
    {
     String attr = attrs[i];
     Label label = new Label(this.composite, SWT.NONE);
     label.setText(attr + ":");

     new Text(this.composite, SWT.NONE);
    }
    pack();
}

As shown in the eclipse corner article Creating JFace Wizards:

We can change the order of the wizard pages by overwriting the getNextPage method of any wizard page.Before leaving the page, we save in the model the values chosen by the user. In our example, depending on the choice of travel the user will next see either the page with flights or the page for travelling by car.

public IWizardPage getNextPage(){
   saveDataToModel();    
   if (planeButton.getSelection()) {
       PlanePage page = ((HolidayWizard)getWizard()).planePage;
     page.onEnterPage();
       return page;
   }
   // Returns the next page depending on the selected button
   if (carButton.getSelection()) { 
    return ((HolidayWizard)getWizard()).carPage;
   }
   return null;
}

We define a method to do this initialization for the PlanePage, onEnterPage() and we invoke this method when moving to the PlanePage, that is in the getNextPage() method for the first page.

Answer 2

If you want to start a new wizard based on your selection on the first page, you can use the JFace base class org.eclipse.jface.wizard.WizardSelectionPage.

The example below shows a list of available wizards defined by an extension point. When you press Next, the selected wizard is started.

public class ModelSetupWizardSelectionPage extends WizardSelectionPage {

private ComboViewer providerViewer;
private IConfigurationElement selectedProvider;

public ModelSetupWizardSelectionPage(String pageName) {
 super(pageName);
}

private class WizardNode implements IWizardNode {
 private IWizard wizard = null;
 private IConfigurationElement configurationElement;

 public WizardNode(IConfigurationElement c) {
  this.configurationElement = c;
 }

 @Override
 public void dispose() {

 }

 @Override
 public Point getExtent() {
  return new Point(-1, -1);
 }

 @Override
 public IWizard getWizard() {
  if (wizard == null) {
   try {
    wizard = (IWizard) configurationElement
      .createExecutableExtension("wizardClass");
   } catch (CoreException e) {

   }
  }
  return wizard;
 }

 @Override
 public boolean isContentCreated() {
  // TODO Auto-generated method stub
  return wizard != null;
 }

}

@Override
public void createControl(Composite parent) {
 setTitle("Select model provider");
 Composite main = new Composite(parent, SWT.NONE);
 GridLayout gd = new GridLayout(2, false);
 main.setLayout(gd);
 new Label(main, SWT.NONE).setText("Model provider");
 Combo providerList = new Combo(main, SWT.NONE);
 providerViewer = new ComboViewer(providerList);
 providerViewer.setLabelProvider(new LabelProvider() {
  @Override
  public String getText(Object element) {
   if (element instanceof IConfigurationElement) {
    IConfigurationElement c = (IConfigurationElement) element;
    String result = c.getAttribute("name");
    if (result == null || result.length() == 0) {
     result = c.getAttribute("class");
    }
    return result;
   }
   return super.getText(element);
  }

 });
 providerViewer
   .addSelectionChangedListener(new ISelectionChangedListener() {
    @Override
    public void selectionChanged(SelectionChangedEvent event) {
     ISelection selection = event.getSelection();
     if (!selection.isEmpty()
       && selection instanceof IStructuredSelection) {
      Object o = ((IStructuredSelection) selection)
        .getFirstElement();
      if (o instanceof IConfigurationElement) {
       selectedProvider = (IConfigurationElement) o;
       setMessage(selectedProvider.getAttribute("description"));
       setSelectedNode(new WizardNode(selectedProvider));
      }
     }

    }
   });
 providerViewer.setContentProvider(new ArrayContentProvider());
 List<IConfigurationElement> providers = new ArrayList<IConfigurationElement>();
 IExtensionRegistry registry = Platform.getExtensionRegistry();
 IExtensionPoint extensionPoint = registry
   .getExtensionPoint(<your extension point namespace>,<extension point name>);
 if (extensionPoint != null) {
  IExtension extensions[] = extensionPoint.getExtensions();
  for (IExtension extension : extensions) {
   IConfigurationElement configurationElements[] = extension
     .getConfigurationElements();
   for (IConfigurationElement c : configurationElements) {
    providers.add(c);
   }
  }
 }
 providerViewer.setInput(providers);
 setControl(main);

}

The corresponding wizard class looks like this:

public class ModelSetupWizard extends Wizard {

private ModelSetupWizardSelectionPage wizardSelectionPage;

public ModelSetupWizard() {
 setForcePreviousAndNextButtons(true);
}

@Override
public boolean performFinish() {
            // Do what you have to do to finish the wizard
 return true;
}

@Override
public void addPages() {
 wizardSelectionPage = new ModelSetupWizardSelectionPage("Select a wizard");
 addPage(wizardSelectionPage);

}

}