examples/org.eclipse.jface.examples.databinding/src/org/eclipse/jface/examples/databinding/snippets/Snippet004DataBindingContextErrorLabel.java

/*******************************************************************************
 * Copyright (c) 2006, 2018 Brad Reynolds and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     Brad Reynolds - initial API and implementation
 *     Brad Reynolds - bug 116920, 159768
 *     Matthew Hall - bug 260329
 *     Hendrik Still <hendrik.still@vogella.com> - Bug 434283
 *     Simon Scholz <simon.scholz@vogella.com> - Bug 489106
 ******************************************************************************/

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

import org.eclipse.core.databinding.AggregateValidationStatus;
import org.eclipse.core.databinding.DataBindingContext;
import org.eclipse.core.databinding.UpdateValueStrategy;
import org.eclipse.core.databinding.observable.Realm;
import org.eclipse.core.databinding.observable.value.IObservableValue;
import org.eclipse.core.databinding.observable.value.WritableValue;
import org.eclipse.core.databinding.validation.IValidator;
import org.eclipse.core.databinding.validation.ValidationStatus;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.jface.databinding.swt.DisplayRealm;
import org.eclipse.jface.databinding.swt.WidgetProperties;
import org.eclipse.jface.layout.GridDataFactory;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;

/**
 * Snippet that displays how to bind the validation error of the
 * {@link DataBindingContext} to a label. http://www.eclipse.org
 *
 * @since 3.2
 */
public class Snippet004DataBindingContextErrorLabel {
	public static void main(String[] args) {
		final Display display = new Display();
		Realm.runWithDefault(DisplayRealm.getRealm(display), () -> {
			Shell shell = new Shell(display);
			shell.setText("Data Binding Snippet 004");
			shell.setLayout(new GridLayout(2, false));

			new Label(shell, SWT.NONE).setText("Enter '5' to be valid:");

			Text text = new Text(shell, SWT.BORDER);
			WritableValue<String> value = WritableValue.withValueType(String.class);
			new Label(shell, SWT.NONE).setText("Error:");

			Label errorLabel = new Label(shell, SWT.BORDER);
			errorLabel.setForeground(display.getSystemColor(SWT.COLOR_RED));
			GridDataFactory.swtDefaults().hint(200, SWT.DEFAULT).applyTo(errorLabel);

			DataBindingContext dbc = new DataBindingContext();

			// Bind the text to the value.
			dbc.bindValue((IObservableValue<String>) WidgetProperties.text(SWT.Modify).observe(text), value,
					new UpdateValueStrategy<String, String>().setAfterConvertValidator(new FiveValidator()), null);

			// Bind the error label to the validation error on the dbc.
			dbc.bindValue(WidgetProperties.text().observe(errorLabel),
					new AggregateValidationStatus(dbc.getBindings(), AggregateValidationStatus.MAX_SEVERITY));

			shell.pack();
			shell.open();
			while (!shell.isDisposed()) {
				if (!display.readAndDispatch())
					display.sleep();
			}
		});
		display.dispose();
	}

	/**
	 * Validator that returns validation errors for any value other than 5.
	 *
	 * @since 3.2
	 */
	private static class FiveValidator implements IValidator<String> {
		@Override
		public IStatus validate(String value) {
			return ("5".equals(value)) ? Status.OK_STATUS : ValidationStatus
					.error("the value was '" + value + "', not '5'");
		}
	}
}