examples/org.eclipse.jface.examples.databinding/src/org/eclipse/jface/examples/databinding/snippets/Snippet003UpdateComboBindUsingViewer.java

/*******************************************************************************
 * Copyright (c) 2006, 2018 The Pampered Chef, Inc. 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:
 *     The Pampered Chef, Inc. - initial API and implementation
 *     Brad Reynolds - bug 116920
 *     Matthew Hall - bugs 260329, 260337
 *     Simon Scholz <simon.scholz@vogella.com> - Bug 434283
 ******************************************************************************/

package org.eclipse.jface.examples.databinding.snippets;

import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.databinding.DataBindingContext;
import org.eclipse.core.databinding.beans.BeanProperties;
import org.eclipse.core.databinding.observable.Realm;
import org.eclipse.core.databinding.property.Properties;
import org.eclipse.jface.databinding.swt.DisplayRealm;
import org.eclipse.jface.databinding.viewers.ViewerSupport;
import org.eclipse.jface.databinding.viewers.ViewersObservables;
import org.eclipse.jface.viewers.ComboViewer;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.layout.RowLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Combo;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

/**
 * Shows how to bind a Combo so that when update its items, the selection is
 * retained if at all possible.
 *
 * @since 3.2
 */
public class Snippet003UpdateComboBindUsingViewer {
	public static void main(String[] args) {
		final Display display = new Display();
		Realm.runWithDefault(DisplayRealm.getRealm(display), () -> {
			ViewModel viewModel = new ViewModel();
			Shell shell = new View(viewModel).createShell();

			// The SWT event loop
			while (!shell.isDisposed()) {
				if (!display.readAndDispatch()) {
					display.sleep();
				}
			}
			// Print the results
			System.out.println(viewModel.getText());
		});
		display.dispose();
	}

	// Minimal JavaBeans support
	public static abstract class AbstractModelObject {
		private PropertyChangeSupport propertyChangeSupport = new PropertyChangeSupport(
				this);

		public void addPropertyChangeListener(PropertyChangeListener listener) {
			propertyChangeSupport.addPropertyChangeListener(listener);
		}

		public void addPropertyChangeListener(String propertyName,
				PropertyChangeListener listener) {
			propertyChangeSupport.addPropertyChangeListener(propertyName,
					listener);
		}

		public void removePropertyChangeListener(PropertyChangeListener listener) {
			propertyChangeSupport.removePropertyChangeListener(listener);
		}

		public void removePropertyChangeListener(String propertyName,
				PropertyChangeListener listener) {
			propertyChangeSupport.removePropertyChangeListener(propertyName,
					listener);
		}

		protected void firePropertyChange(String propertyName, Object oldValue,
				Object newValue) {
			propertyChangeSupport.firePropertyChange(propertyName, oldValue,
					newValue);
		}
	}

	// The View's model--the root of our Model graph for this particular GUI.
	public static class ViewModel extends AbstractModelObject {
		private String text = "beef";

		private List choices = new ArrayList();
		{
			choices.add("pork");
			choices.add("beef");
			choices.add("poultry");
			choices.add("vegatables");
		}

		public List getChoices() {
			return choices;
		}

		public void setChoices(List choices) {
			this.choices = choices;
			firePropertyChange("choices", null, null);
		}

		public String getText() {
			return text;
		}

		public void setText(String text) {
			String oldValue = this.text;
			this.text = text;
			firePropertyChange("text", oldValue, text);
		}
	}

	// The GUI view
	static class View {
		private ViewModel viewModel;

		public View(ViewModel viewModel) {
			this.viewModel = viewModel;
		}

		public Shell createShell() {
			// Build a UI
			Shell shell = new Shell(Display.getCurrent());
			shell.setLayout(new RowLayout(SWT.VERTICAL));

			Combo combo = new Combo(shell, SWT.BORDER | SWT.READ_ONLY);
			ComboViewer viewer = new ComboViewer(combo);
			Button reset = new Button(shell, SWT.NULL);
			reset.setText("reset collection");
			reset.addSelectionListener(new SelectionAdapter() {
				@Override
				public void widgetSelected(SelectionEvent e) {
					List newList = new ArrayList();
					newList.add("Chocolate");
					newList.add("Vanilla");
					newList.add("Mango Parfait");
					newList.add("beef");
					newList.add("Cheesecake");
					viewModel.setChoices(newList);
				}
			});

			// Print value out first
			System.out.println(viewModel.getText());

			DataBindingContext dbc = new DataBindingContext();
			ViewerSupport.bind(viewer,
					BeanProperties.list(viewModel.getClass(), "choices", String.class).observe(viewModel),
					Properties
					.selfValue(String.class));

			dbc.bindValue(ViewersObservables.observeSingleSelection(viewer), BeanProperties.value(viewModel.getClass(), "text").observe(
					viewModel));

			// Open and return the Shell
			shell.pack();
			shell.open();
			return shell;
		}
	}
}