org.eclipse.xwt.tests/samples/org/eclipse/xwt/tests/snipppets/Snippet021MultiFieldValidation.java - xwt/org.eclipse.xwt - Git at Google

 /*******************************************************************************
  * Copyright (c) 2008, 2009 Matthew Hall and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  *     Matthew Hall - initial API and implementation (bug 218269)
  *     Matthew Hall - bug 260329
  ******************************************************************************/

 package org.eclipse.xwt.tests.snipppets;

 import java.util.ArrayList;
 import java.util.Iterator;

 import org.eclipse.core.databinding.DataBindingContext;
 import org.eclipse.core.databinding.observable.Realm;
 import org.eclipse.core.databinding.observable.list.IObservableList;
 import org.eclipse.core.databinding.observable.list.WritableList;
 import org.eclipse.core.databinding.observable.value.IObservableValue;
 import org.eclipse.core.databinding.observable.value.WritableValue;
 import org.eclipse.core.databinding.validation.MultiValidator;
 import org.eclipse.core.databinding.validation.ValidationStatus;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.jface.databinding.swt.SWTObservables;
 import org.eclipse.jface.databinding.viewers.ObservableListContentProvider;
 import org.eclipse.jface.databinding.wizard.WizardPageSupport;
 import org.eclipse.jface.dialogs.IInputValidator;
 import org.eclipse.jface.dialogs.InputDialog;
 import org.eclipse.jface.viewers.IStructuredSelection;
 import org.eclipse.jface.viewers.ListViewer;
 import org.eclipse.jface.window.Window;
 import org.eclipse.jface.wizard.IWizard;
 import org.eclipse.jface.wizard.Wizard;
 import org.eclipse.jface.wizard.WizardDialog;
 import org.eclipse.jface.wizard.WizardPage;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.SelectionAdapter;
 import org.eclipse.swt.events.SelectionEvent;
 import org.eclipse.swt.layout.GridData;
 import org.eclipse.swt.layout.GridLayout;
 import org.eclipse.swt.widgets.Button;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Group;
 import org.eclipse.swt.widgets.Label;
 import org.eclipse.swt.widgets.List;
 import org.eclipse.swt.widgets.Text;

 /**
  * @since 3.2
  *
  */
 public class Snippet021MultiFieldValidation extends WizardPage {

 	private List list_1;
 	private List list;
 	private Button addAddendButton;
 	private Button removeAddendButton;
 	private Text sumModelValue;
 	private Text field2ModelValue;
 	private Text field1ModelValue;
 	private Text sumTarget;
 	private Text field2Target;
 	private Text field1Target;
 	private ListViewer addendsTarget;
 	private ListViewer addendsModelValue;

 	/**
 	 * Create the wizard
 	 */
 	public Snippet021MultiFieldValidation() {
 		super("snippet021");
 		setTitle("Snippet 021 - Multi-field Validators");
 		setDescription("Enter values which satisfy the cross-field constraints");
 	}

 	/**
 	 * Create nameMap of the wizard
 	 *
 	 * @param parent
 	 */
 	public void createControl(Composite parent) {
 		Composite container = new Composite(parent, SWT.NULL);
 		final GridLayout gridLayout = new GridLayout();
 		gridLayout.numColumns = 2;
 		container.setLayout(gridLayout);
 		//
 		setControl(container);

 		final Group bothEvenOrGroup = new Group(container, SWT.NONE);
 		bothEvenOrGroup.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false,
 				false));
 		bothEvenOrGroup.setText("Numbers must be both even or both odd");
 		final GridLayout gridLayout_1 = new GridLayout();
 		gridLayout_1.numColumns = 3;
 		bothEvenOrGroup.setLayout(gridLayout_1);
 		new Label(bothEvenOrGroup, SWT.NONE);

 		final Label targetLabel = new Label(bothEvenOrGroup, SWT.NONE);
 		targetLabel.setText("Target");

 		final Label modelLabel = new Label(bothEvenOrGroup, SWT.NONE);
 		modelLabel.setText("Model");

 		final Label field1Label = new Label(bothEvenOrGroup, SWT.NONE);
 		field1Label.setText("Field 1");

 		field1Target = new Text(bothEvenOrGroup, SWT.BORDER);
 		final GridData gd_field1Target = new GridData(SWT.FILL, SWT.CENTER,
 				true, false);
 		field1Target.setLayoutData(gd_field1Target);

 		field1ModelValue = new Text(bothEvenOrGroup, SWT.READ_ONLY | SWT.BORDER);
 		final GridData gd_field1ModelValue = new GridData(SWT.FILL, SWT.CENTER,
 				true, false);
 		field1ModelValue.setLayoutData(gd_field1ModelValue);

 		final Label field2Label = new Label(bothEvenOrGroup, SWT.NONE);
 		field2Label.setText("Field 2");

 		field2Target = new Text(bothEvenOrGroup, SWT.BORDER);
 		final GridData gd_field2Target = new GridData(SWT.FILL, SWT.CENTER,
 				true, false);
 		field2Target.setLayoutData(gd_field2Target);

 		field2ModelValue = new Text(bothEvenOrGroup, SWT.READ_ONLY | SWT.BORDER);
 		final GridData gd_field2ModelValue = new GridData(SWT.FILL, SWT.CENTER,
 				true, false);
 		field2ModelValue.setLayoutData(gd_field2ModelValue);

 		final Group sumOfAllGroup = new Group(container, SWT.NONE);
 		sumOfAllGroup.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false,
 				true));
 		sumOfAllGroup.setText("Addends must add up to sum");
 		final GridLayout gridLayout_2 = new GridLayout();
 		gridLayout_2.numColumns = 3;
 		sumOfAllGroup.setLayout(gridLayout_2);
 		new Label(sumOfAllGroup, SWT.NONE);

 		final Label targetLabel_1 = new Label(sumOfAllGroup, SWT.NONE);
 		targetLabel_1.setText("Target");

 		final Label modelLabel_1 = new Label(sumOfAllGroup, SWT.NONE);
 		modelLabel_1.setText("Model");

 		final Label expectedSumLabel = new Label(sumOfAllGroup, SWT.NONE);
 		expectedSumLabel.setText("Sum");

 		sumTarget = new Text(sumOfAllGroup, SWT.BORDER);
 		final GridData gd_sumTarget = new GridData(SWT.FILL, SWT.CENTER, true,
 				false);
 		sumTarget.setLayoutData(gd_sumTarget);

 		sumModelValue = new Text(sumOfAllGroup, SWT.READ_ONLY | SWT.BORDER);
 		final GridData gd_sumModelValue = new GridData(SWT.FILL, SWT.CENTER,
 				true, false);
 		sumModelValue.setLayoutData(gd_sumModelValue);

 		final Label addendsLabel = new Label(sumOfAllGroup, SWT.NONE);
 		addendsLabel.setText("Addends");

 		addendsTarget = new ListViewer(sumOfAllGroup, SWT.V_SCROLL | SWT.BORDER);
 		list_1 = addendsTarget.getList();
 		list_1
 				.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, true, 1,
 						2));

 		addendsModelValue = new ListViewer(sumOfAllGroup, SWT.V_SCROLL
 				| SWT.BORDER);
 		list = addendsModelValue.getList();
 		list.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, true, 1, 2));

 		final Composite composite = new Composite(sumOfAllGroup, SWT.NONE);
 		composite.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
 		final GridLayout gridLayout_3 = new GridLayout();
 		gridLayout_3.marginWidth = 0;
 		gridLayout_3.marginHeight = 0;
 		composite.setLayout(gridLayout_3);

 		addAddendButton = new Button(composite, SWT.NONE);
 		addAddendButton.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, false,
 				false));
 		addAddendButton.setText("Add");

 		removeAddendButton = new Button(composite, SWT.NONE);
 		removeAddendButton.setLayoutData(new GridData(SWT.FILL, SWT.CENTER,
 				false, false));
 		removeAddendButton.setText("Remove");

 		bindUI();
 	}

 	private void bindUI() {
 		DataBindingContext dbc = new DataBindingContext();

 		bindEvensAndOddsGroup(dbc);
 		bindSumAndAddendsGroup(dbc);

 		WizardPageSupport.create(this, dbc);
 	}

 	private void bindEvensAndOddsGroup(DataBindingContext dbc) {
 		IObservableValue targetField1 = SWTObservables.observeText(
 				field1Target, SWT.Modify);
 		final IObservableValue middleField1 = new WritableValue(null,
 				Integer.TYPE);
 		dbc.bindValue(targetField1, middleField1);

 		IObservableValue targetField2 = SWTObservables.observeText(
 				field2Target, SWT.Modify);
 		final IObservableValue middleField2 = new WritableValue(null,
 				Integer.TYPE);
 		dbc.bindValue(targetField2, middleField2);

 		MultiValidator validator = new MultiValidator() {
 			protected IStatus validate() {
 				Integer field1 = (Integer) middleField1.getValue();
 				Integer field2 = (Integer) middleField2.getValue();
 				if (Math.abs(field1.intValue()) % 2 != Math.abs(field2
 						.intValue()) % 2)
 					return ValidationStatus
 							.error("Fields 1 and 2 must be both even or both odd");
 				return null;
 			}
 		};
 		dbc.addValidationStatusProvider(validator);

 		IObservableValue modelField1 = new WritableValue(new Integer(1),
 				Integer.TYPE);
 		IObservableValue modelField2 = new WritableValue(new Integer(4),
 				Integer.TYPE);
 		dbc.bindValue(validator.observeValidatedValue(middleField1),
 				modelField1);
 		dbc.bindValue(validator.observeValidatedValue(middleField2),
 				modelField2);

 		dbc.bindValue(SWTObservables.observeText(field1ModelValue, SWT.Modify),
 				modelField1);
 		dbc.bindValue(SWTObservables.observeText(field2ModelValue, SWT.Modify),
 				modelField2);
 	}

 	private void bindSumAndAddendsGroup(DataBindingContext dbc) {
 		IObservableValue targetSum = SWTObservables.observeText(sumTarget,
 				SWT.Modify);
 		final IObservableValue middleSum = new WritableValue(null, Integer.TYPE);
 		dbc.bindValue(targetSum, middleSum);

 		final IObservableList targetAddends = new WritableList(new ArrayList(),
 				Integer.TYPE);
 		addendsTarget.setContentProvider(new ObservableListContentProvider());
 		addendsTarget.setInput(targetAddends);

 		addAddendButton.addSelectionListener(new SelectionAdapter() {
 			public void widgetSelected(final SelectionEvent e) {
 				InputDialog dialog = new InputDialog(getShell(),
 						"Input addend", "Enter an integer addend", "0",
 						new IInputValidator() {
 							public String isValid(String newText) {
 								try {
 									Integer.valueOf(newText);
 									return null;
 								} catch (NumberFormatException e) {
 									return "Enter a number between "
 											+ Integer.MIN_VALUE + " and "
 											+ Integer.MAX_VALUE;
 								}
 							}
 						});
 				if (dialog.open() == Window.OK) {
 					targetAddends.add(Integer.valueOf(dialog.getValue()));
 				}
 			}
 		});

 		removeAddendButton.addSelectionListener(new SelectionAdapter() {
 			public void widgetSelected(SelectionEvent e) {
 				IStructuredSelection selection = (IStructuredSelection) addendsTarget
 						.getSelection();
 				if (!selection.isEmpty())
 					targetAddends.remove(selection.getFirstElement());
 			}
 		});

 		IObservableValue modelSum = new WritableValue(new Integer(5),
 				Integer.TYPE);
 		dbc.bindValue(SWTObservables.observeText(sumModelValue, SWT.Modify),
 				modelSum);

 		IObservableList modelAddends = new WritableList(new ArrayList(),
 				Integer.TYPE);

 		MultiValidator validator = new MultiValidator() {
 			protected IStatus validate() {
 				Integer sum = (Integer) middleSum.getValue();
 				int actualSum = 0;
 				for (Iterator iterator = targetAddends.iterator(); iterator
 						.hasNext();) {
 					actualSum += ((Integer) iterator.next()).intValue();
 				}
 				if (sum.intValue() != actualSum)
 					return ValidationStatus.error("Sum of addends is "
 							+ actualSum + ", expecting " + sum);
 				return ValidationStatus.ok();
 			}
 		};
 		dbc.addValidationStatusProvider(validator);

 		addendsModelValue
 				.setContentProvider(new ObservableListContentProvider());
 		addendsModelValue.setInput(modelAddends);

 		dbc.bindValue(validator.observeValidatedValue(middleSum), modelSum);
 		dbc.bindList(validator.observeValidatedList(targetAddends),
 				modelAddends);
 	}

 	static class MultiFieldValidationWizard extends Wizard {
 		public void addPages() {
 			addPage(new Snippet021MultiFieldValidation());
 		}

 		public String getWindowTitle() {
 			return "Snippet 021 - Multi-field Validation";
 		}

 		public boolean performFinish() {
 			return true;
 		}
 	}

 	public static void main(String[] args) {
 		Display display = new Display();

 		Realm.runWithDefault(SWTObservables.getRealm(display), new Runnable() {
 			public void run() {
 				IWizard wizard = new MultiFieldValidationWizard();
 				WizardDialog dialog = new WizardDialog(null, wizard);
 				dialog.open();

 				// The SWT event loop
 				Display display = Display.getCurrent();
 				while (dialog.getShell() != null
 						&& !dialog.getShell().isDisposed()) {
 					if (!display.readAndDispatch()) {
 						display.sleep();
 					}
 				}
 			}
 		});

 		display.dispose();
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2008, 2009 Matthew Hall and others.
	* All rights reserved. This program and the accompanying materials
	* are made available under the terms of the Eclipse Public License v1.0
	* which accompanies this distribution, and is available at
	* http://www.eclipse.org/legal/epl-v10.html
	*
	* Contributors:
	* Matthew Hall - initial API and implementation (bug 218269)
	* Matthew Hall - bug 260329
	******************************************************************************/

	package org.eclipse.xwt.tests.snipppets;

	import java.util.ArrayList;
	import java.util.Iterator;

	import org.eclipse.core.databinding.DataBindingContext;
	import org.eclipse.core.databinding.observable.Realm;
	import org.eclipse.core.databinding.observable.list.IObservableList;
	import org.eclipse.core.databinding.observable.list.WritableList;
	import org.eclipse.core.databinding.observable.value.IObservableValue;
	import org.eclipse.core.databinding.observable.value.WritableValue;
	import org.eclipse.core.databinding.validation.MultiValidator;
	import org.eclipse.core.databinding.validation.ValidationStatus;
	import org.eclipse.core.runtime.IStatus;
	import org.eclipse.jface.databinding.swt.SWTObservables;
	import org.eclipse.jface.databinding.viewers.ObservableListContentProvider;
	import org.eclipse.jface.databinding.wizard.WizardPageSupport;
	import org.eclipse.jface.dialogs.IInputValidator;
	import org.eclipse.jface.dialogs.InputDialog;
	import org.eclipse.jface.viewers.IStructuredSelection;
	import org.eclipse.jface.viewers.ListViewer;
	import org.eclipse.jface.window.Window;
	import org.eclipse.jface.wizard.IWizard;
	import org.eclipse.jface.wizard.Wizard;
	import org.eclipse.jface.wizard.WizardDialog;
	import org.eclipse.jface.wizard.WizardPage;
	import org.eclipse.swt.SWT;
	import org.eclipse.swt.events.SelectionAdapter;
	import org.eclipse.swt.events.SelectionEvent;
	import org.eclipse.swt.layout.GridData;
	import org.eclipse.swt.layout.GridLayout;
	import org.eclipse.swt.widgets.Button;
	import org.eclipse.swt.widgets.Composite;
	import org.eclipse.swt.widgets.Display;
	import org.eclipse.swt.widgets.Group;
	import org.eclipse.swt.widgets.Label;
	import org.eclipse.swt.widgets.List;
	import org.eclipse.swt.widgets.Text;

	/**
	* @since 3.2
	*
	*/
	public class Snippet021MultiFieldValidation extends WizardPage {

	private List list_1;
	private List list;
	private Button addAddendButton;
	private Button removeAddendButton;
	private Text sumModelValue;
	private Text field2ModelValue;
	private Text field1ModelValue;
	private Text sumTarget;
	private Text field2Target;
	private Text field1Target;
	private ListViewer addendsTarget;
	private ListViewer addendsModelValue;

	/**
	* Create the wizard
	*/
	public Snippet021MultiFieldValidation() {
	super("snippet021");
	setTitle("Snippet 021 - Multi-field Validators");
	setDescription("Enter values which satisfy the cross-field constraints");
	}

	/**
	* Create nameMap of the wizard
	*
	* @param parent
	*/
	public void createControl(Composite parent) {
	Composite container = new Composite(parent, SWT.NULL);
	final GridLayout gridLayout = new GridLayout();
	gridLayout.numColumns = 2;
	container.setLayout(gridLayout);
	//
	setControl(container);

	final Group bothEvenOrGroup = new Group(container, SWT.NONE);
	bothEvenOrGroup.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false,
	false));
	bothEvenOrGroup.setText("Numbers must be both even or both odd");
	final GridLayout gridLayout_1 = new GridLayout();
	gridLayout_1.numColumns = 3;
	bothEvenOrGroup.setLayout(gridLayout_1);
	new Label(bothEvenOrGroup, SWT.NONE);

	final Label targetLabel = new Label(bothEvenOrGroup, SWT.NONE);
	targetLabel.setText("Target");

	final Label modelLabel = new Label(bothEvenOrGroup, SWT.NONE);
	modelLabel.setText("Model");

	final Label field1Label = new Label(bothEvenOrGroup, SWT.NONE);
	field1Label.setText("Field 1");

	field1Target = new Text(bothEvenOrGroup, SWT.BORDER);
	final GridData gd_field1Target = new GridData(SWT.FILL, SWT.CENTER,
	true, false);
	field1Target.setLayoutData(gd_field1Target);

	field1ModelValue = new Text(bothEvenOrGroup, SWT.READ_ONLY \| SWT.BORDER);
	final GridData gd_field1ModelValue = new GridData(SWT.FILL, SWT.CENTER,
	true, false);
	field1ModelValue.setLayoutData(gd_field1ModelValue);

	final Label field2Label = new Label(bothEvenOrGroup, SWT.NONE);
	field2Label.setText("Field 2");

	field2Target = new Text(bothEvenOrGroup, SWT.BORDER);
	final GridData gd_field2Target = new GridData(SWT.FILL, SWT.CENTER,
	true, false);
	field2Target.setLayoutData(gd_field2Target);

	field2ModelValue = new Text(bothEvenOrGroup, SWT.READ_ONLY \| SWT.BORDER);
	final GridData gd_field2ModelValue = new GridData(SWT.FILL, SWT.CENTER,
	true, false);
	field2ModelValue.setLayoutData(gd_field2ModelValue);

	final Group sumOfAllGroup = new Group(container, SWT.NONE);
	sumOfAllGroup.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false,
	true));
	sumOfAllGroup.setText("Addends must add up to sum");
	final GridLayout gridLayout_2 = new GridLayout();
	gridLayout_2.numColumns = 3;
	sumOfAllGroup.setLayout(gridLayout_2);
	new Label(sumOfAllGroup, SWT.NONE);

	final Label targetLabel_1 = new Label(sumOfAllGroup, SWT.NONE);
	targetLabel_1.setText("Target");

	final Label modelLabel_1 = new Label(sumOfAllGroup, SWT.NONE);
	modelLabel_1.setText("Model");

	final Label expectedSumLabel = new Label(sumOfAllGroup, SWT.NONE);
	expectedSumLabel.setText("Sum");

	sumTarget = new Text(sumOfAllGroup, SWT.BORDER);
	final GridData gd_sumTarget = new GridData(SWT.FILL, SWT.CENTER, true,
	false);
	sumTarget.setLayoutData(gd_sumTarget);

	sumModelValue = new Text(sumOfAllGroup, SWT.READ_ONLY \| SWT.BORDER);
	final GridData gd_sumModelValue = new GridData(SWT.FILL, SWT.CENTER,
	true, false);
	sumModelValue.setLayoutData(gd_sumModelValue);

	final Label addendsLabel = new Label(sumOfAllGroup, SWT.NONE);
	addendsLabel.setText("Addends");

	addendsTarget = new ListViewer(sumOfAllGroup, SWT.V_SCROLL \| SWT.BORDER);
	list_1 = addendsTarget.getList();
	list_1
	.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, true, 1,
	2));

	addendsModelValue = new ListViewer(sumOfAllGroup, SWT.V_SCROLL
	\| SWT.BORDER);
	list = addendsModelValue.getList();
	list.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, true, 1, 2));

	final Composite composite = new Composite(sumOfAllGroup, SWT.NONE);
	composite.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
	final GridLayout gridLayout_3 = new GridLayout();
	gridLayout_3.marginWidth = 0;
	gridLayout_3.marginHeight = 0;
	composite.setLayout(gridLayout_3);

	addAddendButton = new Button(composite, SWT.NONE);
	addAddendButton.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, false,
	false));
	addAddendButton.setText("Add");

	removeAddendButton = new Button(composite, SWT.NONE);
	removeAddendButton.setLayoutData(new GridData(SWT.FILL, SWT.CENTER,
	false, false));
	removeAddendButton.setText("Remove");

	bindUI();
	}

	private void bindUI() {
	DataBindingContext dbc = new DataBindingContext();

	bindEvensAndOddsGroup(dbc);
	bindSumAndAddendsGroup(dbc);

	WizardPageSupport.create(this, dbc);
	}

	private void bindEvensAndOddsGroup(DataBindingContext dbc) {
	IObservableValue targetField1 = SWTObservables.observeText(
	field1Target, SWT.Modify);
	final IObservableValue middleField1 = new WritableValue(null,
	Integer.TYPE);
	dbc.bindValue(targetField1, middleField1);

	IObservableValue targetField2 = SWTObservables.observeText(
	field2Target, SWT.Modify);
	final IObservableValue middleField2 = new WritableValue(null,
	Integer.TYPE);
	dbc.bindValue(targetField2, middleField2);

	MultiValidator validator = new MultiValidator() {
	protected IStatus validate() {
	Integer field1 = (Integer) middleField1.getValue();
	Integer field2 = (Integer) middleField2.getValue();
	if (Math.abs(field1.intValue()) % 2 != Math.abs(field2
	.intValue()) % 2)
	return ValidationStatus
	.error("Fields 1 and 2 must be both even or both odd");
	return null;
	}
	};
	dbc.addValidationStatusProvider(validator);

	IObservableValue modelField1 = new WritableValue(new Integer(1),
	Integer.TYPE);
	IObservableValue modelField2 = new WritableValue(new Integer(4),
	Integer.TYPE);
	dbc.bindValue(validator.observeValidatedValue(middleField1),
	modelField1);
	dbc.bindValue(validator.observeValidatedValue(middleField2),
	modelField2);

	dbc.bindValue(SWTObservables.observeText(field1ModelValue, SWT.Modify),
	modelField1);
	dbc.bindValue(SWTObservables.observeText(field2ModelValue, SWT.Modify),
	modelField2);
	}

	private void bindSumAndAddendsGroup(DataBindingContext dbc) {
	IObservableValue targetSum = SWTObservables.observeText(sumTarget,
	SWT.Modify);
	final IObservableValue middleSum = new WritableValue(null, Integer.TYPE);
	dbc.bindValue(targetSum, middleSum);

	final IObservableList targetAddends = new WritableList(new ArrayList(),
	Integer.TYPE);
	addendsTarget.setContentProvider(new ObservableListContentProvider());
	addendsTarget.setInput(targetAddends);

	addAddendButton.addSelectionListener(new SelectionAdapter() {
	public void widgetSelected(final SelectionEvent e) {
	InputDialog dialog = new InputDialog(getShell(),
	"Input addend", "Enter an integer addend", "0",
	new IInputValidator() {
	public String isValid(String newText) {
	try {
	Integer.valueOf(newText);
	return null;
	} catch (NumberFormatException e) {
	return "Enter a number between "
	+ Integer.MIN_VALUE + " and "
	+ Integer.MAX_VALUE;
	}
	}
	});
	if (dialog.open() == Window.OK) {
	targetAddends.add(Integer.valueOf(dialog.getValue()));
	}
	}
	});

	removeAddendButton.addSelectionListener(new SelectionAdapter() {
	public void widgetSelected(SelectionEvent e) {
	IStructuredSelection selection = (IStructuredSelection) addendsTarget
	.getSelection();
	if (!selection.isEmpty())
	targetAddends.remove(selection.getFirstElement());
	}
	});

	IObservableValue modelSum = new WritableValue(new Integer(5),
	Integer.TYPE);
	dbc.bindValue(SWTObservables.observeText(sumModelValue, SWT.Modify),
	modelSum);

	IObservableList modelAddends = new WritableList(new ArrayList(),
	Integer.TYPE);

	MultiValidator validator = new MultiValidator() {
	protected IStatus validate() {
	Integer sum = (Integer) middleSum.getValue();
	int actualSum = 0;
	for (Iterator iterator = targetAddends.iterator(); iterator
	.hasNext();) {
	actualSum += ((Integer) iterator.next()).intValue();
	}
	if (sum.intValue() != actualSum)
	return ValidationStatus.error("Sum of addends is "
	+ actualSum + ", expecting " + sum);
	return ValidationStatus.ok();
	}
	};
	dbc.addValidationStatusProvider(validator);

	addendsModelValue
	.setContentProvider(new ObservableListContentProvider());
	addendsModelValue.setInput(modelAddends);

	dbc.bindValue(validator.observeValidatedValue(middleSum), modelSum);
	dbc.bindList(validator.observeValidatedList(targetAddends),
	modelAddends);
	}

	static class MultiFieldValidationWizard extends Wizard {
	public void addPages() {
	addPage(new Snippet021MultiFieldValidation());
	}

	public String getWindowTitle() {
	return "Snippet 021 - Multi-field Validation";
	}

	public boolean performFinish() {
	return true;
	}
	}

	public static void main(String[] args) {
	Display display = new Display();

	Realm.runWithDefault(SWTObservables.getRealm(display), new Runnable() {
	public void run() {
	IWizard wizard = new MultiFieldValidationWizard();
	WizardDialog dialog = new WizardDialog(null, wizard);
	dialog.open();

	// The SWT event loop
	Display display = Display.getCurrent();
	while (dialog.getShell() != null
	&& !dialog.getShell().isDisposed()) {
	if (!display.readAndDispatch()) {
	display.sleep();
	}
	}
	}
	});

	display.dispose();
	}
	}