org.eclipse.e4.xwt.tests.snipppets.Snippet004DataBindingContextErrorLabel.java Source code

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/*******************************************************************************
 * Copyright (c) 2006, 2010 Brad Reynolds 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:
 *     Brad Reynolds - initial API and implementation
 *     Brad Reynolds - bug 116920, 159768
 *     Matthew Hall - bug 260329
 ******************************************************************************/

package org.eclipse.e4.xwt.tests.snipppets;

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.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.SWTObservables;
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(SWTObservables.getRealm(display), new Runnable() {
            public void run() {
                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 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(SWTObservables.observeText(text, SWT.Modify), value,
                        new UpdateValueStrategy().setAfterConvertValidator(new FiveValidator()), null);

                // Bind the error label to the validation error on the dbc.
                dbc.bindValue(SWTObservables.observeText(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 {
        public IStatus validate(Object value) {
            return ("5".equals(value)) ? Status.OK_STATUS
                    : ValidationStatus.error("the value was '" + value + "', not '5'");
        }
    }
}