jpa/plugins/org.eclipse.jpt.ui/src/org/eclipse/jpt/ui/internal/mappings/details/TargetEntityComposite.java - dali/webtools.dali - Git at Google

 /*******************************************************************************
  * Copyright (c) 2006, 2008 Oracle. 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:
  *     Oracle - initial API and implementation
  ******************************************************************************/
 package org.eclipse.jpt.ui.internal.mappings.details;

 import java.util.Collection;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.jdt.core.IJavaElement;
 import org.eclipse.jdt.core.IJavaProject;
 import org.eclipse.jdt.core.IPackageFragmentRoot;
 import org.eclipse.jdt.core.IType;
 import org.eclipse.jdt.core.JavaCore;
 import org.eclipse.jdt.core.JavaModelException;
 import org.eclipse.jdt.core.search.SearchEngine;
 import org.eclipse.jdt.internal.ui.refactoring.contentassist.ControlContentAssistHelper;
 import org.eclipse.jdt.internal.ui.refactoring.contentassist.JavaTypeCompletionProcessor;
 import org.eclipse.jdt.ui.IJavaElementSearchConstants;
 import org.eclipse.jdt.ui.JavaUI;
 import org.eclipse.jface.fieldassist.FieldDecorationRegistry;
 import org.eclipse.jface.window.Window;
 import org.eclipse.jpt.core.context.RelationshipMapping;
 import org.eclipse.jpt.ui.JptUiPlugin;
 import org.eclipse.jpt.ui.WidgetFactory;
 import org.eclipse.jpt.ui.internal.JpaHelpContextIds;
 import org.eclipse.jpt.ui.internal.mappings.JptUiMappingsMessages;
 import org.eclipse.jpt.ui.internal.util.SWTUtil;
 import org.eclipse.jpt.ui.internal.widgets.FormPane;
 import org.eclipse.jpt.utility.internal.StringTools;
 import org.eclipse.jpt.utility.model.value.PropertyValueModel;
 import org.eclipse.osgi.util.NLS;
 import org.eclipse.swt.custom.BusyIndicator;
 import org.eclipse.swt.events.ModifyEvent;
 import org.eclipse.swt.events.ModifyListener;
 import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.layout.GridData;
 import org.eclipse.swt.widgets.Button;
 import org.eclipse.swt.widgets.Combo;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.ui.PartInitException;
 import org.eclipse.ui.PlatformUI;
 import org.eclipse.ui.dialogs.SelectionDialog;
 import org.eclipse.ui.forms.widgets.Hyperlink;

 /**
  * Here the layout of this pane:
  * <pre>
  * -----------------------------------------------------------------------------
  * |                -------------------------------------------- ------------- |
  * | Target Entity: | I                                      |v| | Browse... | |
  * | ¯¯¯¯¯¯¯¯¯¯¯¯¯¯ -------------------------------------------- ------------- |
  * -----------------------------------------------------------------------------</pre>
  *
  * @see RelationshipMapping
  * @see ManyToManyMappingComposite - A container of this pane
  * @see ManyToOneMappingComposite - A container of this pane
  * @see OneToManyMappingComposite - A container of this pane
  * @see OneToOneMappingComposite - A container of this pane
  *
  * @version 2.0
  * @since 1.0
  */
 @SuppressWarnings("nls")
 public class TargetEntityComposite extends FormPane<RelationshipMapping>
 {
 	private JavaTypeCompletionProcessor javaTypeCompletionProcessor;

 	private Combo combo;

 	/**
 	 * Creates a new <code>TargetEntityComposite</code>.
 	 *
 	 * @param parentPane The parent container of this one
 	 * @param parent The parent container
 	 */
 	public TargetEntityComposite(FormPane<? extends RelationshipMapping> parentPane,
 	                             Composite parent) {

 		super(parentPane, parent);
 	}

 	/**
 	 * Creates a new <code>TargetEntityComposite</code>.
 	 *
 	 * @param subjectHolder The holder of the subject <code>IRelationshipMapping</code>
 	 * @param parent The parent container
 	 * @param widgetFactory The factory used to create various common widgets
 	 */
 	public TargetEntityComposite(PropertyValueModel<? extends RelationshipMapping> subjectHolder,
 	                             Composite parent,
 	                             WidgetFactory widgetFactory) {

 		super(subjectHolder, parent, widgetFactory);
 	}

 	@Override
 	protected void addPropertyNames(Collection<String> propertyNames) {
 		super.addPropertyNames(propertyNames);
 		propertyNames.add(RelationshipMapping.DEFAULT_TARGET_ENTITY_PROPERTY);
 		propertyNames.add(RelationshipMapping.SPECIFIED_TARGET_ENTITY_PROPERTY);
 	}
 	@Override
 	protected void initialize() {
 		super.initialize();

 		// TODO bug 156185 - when this is fixed there should be api for this
 		this.javaTypeCompletionProcessor = new JavaTypeCompletionProcessor(false, false);
 	}

 	@Override
 	protected void initializeLayout(Composite container) {
 		Composite comboPane = addSubPane(container);
 		this.combo = addEditableCombo(comboPane);
 		this.combo.add(JptUiMappingsMessages.DefaultEmpty);
 		this.combo.addModifyListener(buildTargetEntityModifyListener());

 		Image image = FieldDecorationRegistry.getDefault().getFieldDecoration(FieldDecorationRegistry.DEC_CONTENT_PROPOSAL).getImage();
 		GridData data = new GridData(GridData.FILL_HORIZONTAL);
 		data.horizontalIndent = image.getBounds().width;
 		this.combo.setLayoutData(data);

 		ControlContentAssistHelper.createComboContentAssistant(
 			this.combo,
 			javaTypeCompletionProcessor
 		);


 		SWTUtil.attachDefaultValueHandler(this.combo);

 		Hyperlink labelLink = addHyperlink(container,
 			JptUiMappingsMessages.TargetEntityChooser_label,
 			buildOpenTargetEntityAction()
 		);

 		addLabeledComposite(
 			container,
 			labelLink,
 			comboPane,
 			addTargetEntitySelectionButton(container),
 			JpaHelpContextIds.MAPPING_TARGET_ENTITY
 		);
 	}

 	private void openEditor() {

 		String targetEntity = getSubject().getTargetEntity();

 		if (targetEntity != null) {

 			try {
 				IType type = getSubject().getJpaProject().getJavaProject().findType(targetEntity);

 				if (type != null) {
 					IJavaElement javaElement = type.getParent();
 					JavaUI.openInEditor(javaElement, true, true);
 				}
 			}
 			catch (JavaModelException e) {
 				JptUiPlugin.log(e);
 			}
 			catch (PartInitException e) {
 				JptUiPlugin.log(e);
 			}
 		}
 	}
 	private Runnable buildOpenTargetEntityAction() {
 		return new Runnable() {
 			public void run() {
 				TargetEntityComposite.this.openEditor();
 			}
 		};
 	}

 	private Runnable buildOpenTypeAction() {
 		return new Runnable() {
 			public void run() {
 				BusyIndicator.showWhile(combo.getDisplay(), new Runnable() {
 					public void run() {
 						doOpenSelectionDialog();
 					}
 				});
 			}
 		};
 	}

 	private ModifyListener buildTargetEntityModifyListener() {
 		return new ModifyListener() {
 			public void modifyText(ModifyEvent e) {
 				if (!isPopulating()) {
 					Combo combo = (Combo) e.widget;
 					if (combo.getData("populating") != Boolean.TRUE) {//check !TRUE because null is a possibility as well
 						valueChanged(combo.getText());
 					}
 				}
 			}
 		};
 	}

 	private Button addTargetEntitySelectionButton(Composite parent) {
 		return addPushButton(
 			parent,
 			JptUiMappingsMessages.TargetEntityChooser_browse,
 			buildOpenTypeAction()
 		);
 	}

 	private void doOpenSelectionDialog() {
 		SelectionDialog dialog;

 		try {
 			dialog = JavaUI.createTypeDialog(
 				getControl().getShell(),
 				PlatformUI.getWorkbench().getProgressService(),
 				SearchEngine.createWorkspaceScope(),
 				IJavaElementSearchConstants.CONSIDER_ALL_TYPES,
 				false
 			);
 		}
 		catch (JavaModelException e) {
 			JptUiPlugin.log(e);
 			return;
 		}

 		dialog.setTitle(JptUiMappingsMessages.TargetEntityChooser_selectTypeTitle);

 		if (dialog.open() == Window.OK) {
 			IType type = (IType) dialog.getResult()[0];
 			this.combo.setText(type.getFullyQualifiedName('.'));
 		}
 	}

 	@Override
 	protected void doPopulate() {

 		super.doPopulate();
 		populateCombo();
 		updatePackageFragment();
 	}

 	private void updatePackageFragment() {

 		if (getSubject() != null) {
 			IPackageFragmentRoot root = getPackageFragmentRoot();

 			if (root != null) {
 				javaTypeCompletionProcessor.setPackageFragment(root.getPackageFragment(""));
 				return;
 			}
 		}

 		javaTypeCompletionProcessor.setPackageFragment(null);
 	}

 	/**
 	 * Retrieves the ??
 	 *
 	 * @return Either the root of the package fragment or <code>null</code> if it
 	 * can't be retrieved
 	 */
 	protected IPackageFragmentRoot getPackageFragmentRoot() {
 		IProject project = getSubject().getJpaProject().getProject();
 		IJavaProject root = JavaCore.create(project);

 		try {
 			return root.getAllPackageFragmentRoots()[0];
 		}
 		catch (JavaModelException e) {
 			JptUiPlugin.log(e);
 		}
 		return null;
 	}


 	private void populateCombo() {

 		combo.removeAll();
 		populateDefaultValue();
 		// TODO Add possible target entity names
 		updateSelectedItem();
 	}

 	/**
 	 * Adds the default value to the combo if one exists.
 	 */
 	private void populateDefaultValue() {

 		RelationshipMapping entity = getSubject();
 		String defaultValue = (entity != null) ? entity.getDefaultTargetEntity() : null;

 		if (defaultValue != null) {
 			combo.add(NLS.bind(
 				JptUiMappingsMessages.DefaultWithOneParam,
 				defaultValue
 			));
 		}
 		else {
 			combo.add(JptUiMappingsMessages.DefaultEmpty);
 		}
 	}

 	/*
 	 * (non-Javadoc)
 	 */
 	@Override
 	protected void propertyChanged(String propertyName) {
 		super.propertyChanged(propertyName);

 		if (propertyName == RelationshipMapping.DEFAULT_TARGET_ENTITY_PROPERTY ||
 		    propertyName == RelationshipMapping.SPECIFIED_TARGET_ENTITY_PROPERTY) {

 			populateCombo();
 		}
 	}

 	/**
 	 * Updates the selected item by selected the current value, if not
 	 * <code>null</code>, or select the default value if one is available,
 	 * otherwise remove the selection.
 	 * <p>
 	 * <b>Note:</b> It seems the text can be shown as truncated, changing the
 	 * selection to (0, 0) makes the entire text visible.
 	 */
 	private void updateSelectedItem() {
 		RelationshipMapping subject = getSubject();
 		String value = (subject != null) ? subject.getSpecifiedTargetEntity() : null;

 		if (value != null) {
 			combo.setText(value);
 			combo.setSelection(new Point(0, 0));
 		}
 		else {
 			String defaultValue = (subject != null) ? subject.getDefaultTargetEntity() : null;
 			String displayString = JptUiMappingsMessages.DefaultEmpty;

 			if (defaultValue != null) {
 				displayString = NLS.bind(
 					JptUiMappingsMessages.DefaultWithOneParam,
 					defaultValue
 				);
 			}

 			// Selected the default value
 			if (displayString != null) {
 				combo.select(0);
 				combo.setSelection(new Point(0, 0));
 			}
 			// Remove the selection
 			else {
 				combo.select(-1);
 			}
 		}
 	}

 	private void valueChanged(String value) {

 		RelationshipMapping subject = getSubject();
 		String oldValue = (subject != null) ? subject.getSpecifiedTargetEntity() : null;

 		// Check for null value
 		if (StringTools.stringIsEmpty(value)) {
 			value = null;

 			if (StringTools.stringIsEmpty(oldValue)) {
 				return;
 			}
 		}

 		// The default value
 		if (value != null &&
 		    combo.getItemCount() > 0 &&
 		    value.equals(combo.getItem(0)))
 		{
 			value = null;
 		}

 		// Nothing to change
 		if ((oldValue == value) && value == null) {
 			return;
 		}

 		// Set the new value
 		if ((value != null) && (oldValue == null) ||
 		   ((oldValue != null) && !oldValue.equals(value))) {

 			setPopulating(true);

 			try {
 				subject.setSpecifiedTargetEntity(value);
 			}
 			finally {
 				setPopulating(false);
 			}
 		}
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2006, 2008 Oracle. 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:
	* Oracle - initial API and implementation
	******************************************************************************/
	package org.eclipse.jpt.ui.internal.mappings.details;

	import java.util.Collection;
	import org.eclipse.core.resources.IProject;
	import org.eclipse.jdt.core.IJavaElement;
	import org.eclipse.jdt.core.IJavaProject;
	import org.eclipse.jdt.core.IPackageFragmentRoot;
	import org.eclipse.jdt.core.IType;
	import org.eclipse.jdt.core.JavaCore;
	import org.eclipse.jdt.core.JavaModelException;
	import org.eclipse.jdt.core.search.SearchEngine;
	import org.eclipse.jdt.internal.ui.refactoring.contentassist.ControlContentAssistHelper;
	import org.eclipse.jdt.internal.ui.refactoring.contentassist.JavaTypeCompletionProcessor;
	import org.eclipse.jdt.ui.IJavaElementSearchConstants;
	import org.eclipse.jdt.ui.JavaUI;
	import org.eclipse.jface.fieldassist.FieldDecorationRegistry;
	import org.eclipse.jface.window.Window;
	import org.eclipse.jpt.core.context.RelationshipMapping;
	import org.eclipse.jpt.ui.JptUiPlugin;
	import org.eclipse.jpt.ui.WidgetFactory;
	import org.eclipse.jpt.ui.internal.JpaHelpContextIds;
	import org.eclipse.jpt.ui.internal.mappings.JptUiMappingsMessages;
	import org.eclipse.jpt.ui.internal.util.SWTUtil;
	import org.eclipse.jpt.ui.internal.widgets.FormPane;
	import org.eclipse.jpt.utility.internal.StringTools;
	import org.eclipse.jpt.utility.model.value.PropertyValueModel;
	import org.eclipse.osgi.util.NLS;
	import org.eclipse.swt.custom.BusyIndicator;
	import org.eclipse.swt.events.ModifyEvent;
	import org.eclipse.swt.events.ModifyListener;
	import org.eclipse.swt.graphics.Image;
	import org.eclipse.swt.graphics.Point;
	import org.eclipse.swt.layout.GridData;
	import org.eclipse.swt.widgets.Button;
	import org.eclipse.swt.widgets.Combo;
	import org.eclipse.swt.widgets.Composite;
	import org.eclipse.ui.PartInitException;
	import org.eclipse.ui.PlatformUI;
	import org.eclipse.ui.dialogs.SelectionDialog;
	import org.eclipse.ui.forms.widgets.Hyperlink;

	/**
	* Here the layout of this pane:
	* <pre>
	* -----------------------------------------------------------------------------
	* \| -------------------------------------------- ------------- \|
	* \| Target Entity: \| I \|v\| \| Browse... \| \|
	* \| ¯¯¯¯¯¯¯¯¯¯¯¯¯¯ -------------------------------------------- ------------- \|
	* -----------------------------------------------------------------------------</pre>
	*
	* @see RelationshipMapping
	* @see ManyToManyMappingComposite - A container of this pane
	* @see ManyToOneMappingComposite - A container of this pane
	* @see OneToManyMappingComposite - A container of this pane
	* @see OneToOneMappingComposite - A container of this pane
	*
	* @version 2.0
	* @since 1.0
	*/
	@SuppressWarnings("nls")
	public class TargetEntityComposite extends FormPane<RelationshipMapping>
	{
	private JavaTypeCompletionProcessor javaTypeCompletionProcessor;

	private Combo combo;

	/**
	* Creates a new <code>TargetEntityComposite</code>.
	*
	* @param parentPane The parent container of this one
	* @param parent The parent container
	*/
	public TargetEntityComposite(FormPane<? extends RelationshipMapping> parentPane,
	Composite parent) {

	super(parentPane, parent);
	}

	/**
	* Creates a new <code>TargetEntityComposite</code>.
	*
	* @param subjectHolder The holder of the subject <code>IRelationshipMapping</code>
	* @param parent The parent container
	* @param widgetFactory The factory used to create various common widgets
	*/
	public TargetEntityComposite(PropertyValueModel<? extends RelationshipMapping> subjectHolder,
	Composite parent,
	WidgetFactory widgetFactory) {

	super(subjectHolder, parent, widgetFactory);
	}

	@Override
	protected void addPropertyNames(Collection<String> propertyNames) {
	super.addPropertyNames(propertyNames);
	propertyNames.add(RelationshipMapping.DEFAULT_TARGET_ENTITY_PROPERTY);
	propertyNames.add(RelationshipMapping.SPECIFIED_TARGET_ENTITY_PROPERTY);
	}
	@Override
	protected void initialize() {
	super.initialize();

	// TODO bug 156185 - when this is fixed there should be api for this
	this.javaTypeCompletionProcessor = new JavaTypeCompletionProcessor(false, false);
	}

	@Override
	protected void initializeLayout(Composite container) {
	Composite comboPane = addSubPane(container);
	this.combo = addEditableCombo(comboPane);
	this.combo.add(JptUiMappingsMessages.DefaultEmpty);
	this.combo.addModifyListener(buildTargetEntityModifyListener());

	Image image = FieldDecorationRegistry.getDefault().getFieldDecoration(FieldDecorationRegistry.DEC_CONTENT_PROPOSAL).getImage();
	GridData data = new GridData(GridData.FILL_HORIZONTAL);
	data.horizontalIndent = image.getBounds().width;
	this.combo.setLayoutData(data);

	ControlContentAssistHelper.createComboContentAssistant(
	this.combo,
	javaTypeCompletionProcessor
	);



	SWTUtil.attachDefaultValueHandler(this.combo);

	Hyperlink labelLink = addHyperlink(container,
	JptUiMappingsMessages.TargetEntityChooser_label,
	buildOpenTargetEntityAction()
	);

	addLabeledComposite(
	container,
	labelLink,
	comboPane,
	addTargetEntitySelectionButton(container),
	JpaHelpContextIds.MAPPING_TARGET_ENTITY
	);
	}

	private void openEditor() {

	String targetEntity = getSubject().getTargetEntity();

	if (targetEntity != null) {

	try {
	IType type = getSubject().getJpaProject().getJavaProject().findType(targetEntity);

	if (type != null) {
	IJavaElement javaElement = type.getParent();
	JavaUI.openInEditor(javaElement, true, true);
	}
	}
	catch (JavaModelException e) {
	JptUiPlugin.log(e);
	}
	catch (PartInitException e) {
	JptUiPlugin.log(e);
	}
	}
	}
	private Runnable buildOpenTargetEntityAction() {
	return new Runnable() {
	public void run() {
	TargetEntityComposite.this.openEditor();
	}
	};
	}

	private Runnable buildOpenTypeAction() {
	return new Runnable() {
	public void run() {
	BusyIndicator.showWhile(combo.getDisplay(), new Runnable() {
	public void run() {
	doOpenSelectionDialog();
	}
	});
	}
	};
	}

	private ModifyListener buildTargetEntityModifyListener() {
	return new ModifyListener() {
	public void modifyText(ModifyEvent e) {
	if (!isPopulating()) {
	Combo combo = (Combo) e.widget;
	if (combo.getData("populating") != Boolean.TRUE) {//check !TRUE because null is a possibility as well
	valueChanged(combo.getText());
	}
	}
	}
	};
	}

	private Button addTargetEntitySelectionButton(Composite parent) {
	return addPushButton(
	parent,
	JptUiMappingsMessages.TargetEntityChooser_browse,
	buildOpenTypeAction()
	);
	}

	private void doOpenSelectionDialog() {
	SelectionDialog dialog;

	try {
	dialog = JavaUI.createTypeDialog(
	getControl().getShell(),
	PlatformUI.getWorkbench().getProgressService(),
	SearchEngine.createWorkspaceScope(),
	IJavaElementSearchConstants.CONSIDER_ALL_TYPES,
	false
	);
	}
	catch (JavaModelException e) {
	JptUiPlugin.log(e);
	return;
	}

	dialog.setTitle(JptUiMappingsMessages.TargetEntityChooser_selectTypeTitle);

	if (dialog.open() == Window.OK) {
	IType type = (IType) dialog.getResult()[0];
	this.combo.setText(type.getFullyQualifiedName('.'));
	}
	}

	@Override
	protected void doPopulate() {

	super.doPopulate();
	populateCombo();
	updatePackageFragment();
	}

	private void updatePackageFragment() {

	if (getSubject() != null) {
	IPackageFragmentRoot root = getPackageFragmentRoot();

	if (root != null) {
	javaTypeCompletionProcessor.setPackageFragment(root.getPackageFragment(""));
	return;
	}
	}

	javaTypeCompletionProcessor.setPackageFragment(null);
	}

	/**
	* Retrieves the ??
	*
	* @return Either the root of the package fragment or <code>null</code> if it
	* can't be retrieved
	*/
	protected IPackageFragmentRoot getPackageFragmentRoot() {
	IProject project = getSubject().getJpaProject().getProject();
	IJavaProject root = JavaCore.create(project);

	try {
	return root.getAllPackageFragmentRoots()[0];
	}
	catch (JavaModelException e) {
	JptUiPlugin.log(e);
	}
	return null;
	}



	private void populateCombo() {

	combo.removeAll();
	populateDefaultValue();
	// TODO Add possible target entity names
	updateSelectedItem();
	}

	/**
	* Adds the default value to the combo if one exists.
	*/
	private void populateDefaultValue() {

	RelationshipMapping entity = getSubject();
	String defaultValue = (entity != null) ? entity.getDefaultTargetEntity() : null;

	if (defaultValue != null) {
	combo.add(NLS.bind(
	JptUiMappingsMessages.DefaultWithOneParam,
	defaultValue
	));
	}
	else {
	combo.add(JptUiMappingsMessages.DefaultEmpty);
	}
	}

	/*
	* (non-Javadoc)
	*/
	@Override
	protected void propertyChanged(String propertyName) {
	super.propertyChanged(propertyName);

	if (propertyName == RelationshipMapping.DEFAULT_TARGET_ENTITY_PROPERTY \|\|
	propertyName == RelationshipMapping.SPECIFIED_TARGET_ENTITY_PROPERTY) {

	populateCombo();
	}
	}

	/**
	* Updates the selected item by selected the current value, if not
	* <code>null</code>, or select the default value if one is available,
	* otherwise remove the selection.
	* <p>
	* <b>Note:</b> It seems the text can be shown as truncated, changing the
	* selection to (0, 0) makes the entire text visible.
	*/
	private void updateSelectedItem() {
	RelationshipMapping subject = getSubject();
	String value = (subject != null) ? subject.getSpecifiedTargetEntity() : null;

	if (value != null) {
	combo.setText(value);
	combo.setSelection(new Point(0, 0));
	}
	else {
	String defaultValue = (subject != null) ? subject.getDefaultTargetEntity() : null;
	String displayString = JptUiMappingsMessages.DefaultEmpty;

	if (defaultValue != null) {
	displayString = NLS.bind(
	JptUiMappingsMessages.DefaultWithOneParam,
	defaultValue
	);
	}

	// Selected the default value
	if (displayString != null) {
	combo.select(0);
	combo.setSelection(new Point(0, 0));
	}
	// Remove the selection
	else {
	combo.select(-1);
	}
	}
	}

	private void valueChanged(String value) {

	RelationshipMapping subject = getSubject();
	String oldValue = (subject != null) ? subject.getSpecifiedTargetEntity() : null;

	// Check for null value
	if (StringTools.stringIsEmpty(value)) {
	value = null;

	if (StringTools.stringIsEmpty(oldValue)) {
	return;
	}
	}

	// The default value
	if (value != null &&
	combo.getItemCount() > 0 &&
	value.equals(combo.getItem(0)))
	{
	value = null;
	}

	// Nothing to change
	if ((oldValue == value) && value == null) {
	return;
	}

	// Set the new value
	if ((value != null) && (oldValue == null) \|\|
	((oldValue != null) && !oldValue.equals(value))) {

	setPopulating(true);

	try {
	subject.setSpecifiedTargetEntity(value);
	}
	finally {
	setPopulating(false);
	}
	}
	}
	}