org.eclipse.jface.examples.databinding.snippets.Snippet011ValidateMultipleBindingsSnippet.java Source code

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Here is the source code for org.eclipse.jface.examples.databinding.snippets.Snippet011ValidateMultipleBindingsSnippet.java

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/*******************************************************************************
 * Copyright (c) 2007, 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
 *     Lars Vogel <Lars.Vogel@gmail.com> - Bug 434287
 *     Simon Scholz <simon.scholz@vogella.com> - Bug 434283
 ******************************************************************************/

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

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.jface.databinding.swt.DisplayRealm;
import org.eclipse.jface.databinding.swt.typed.WidgetProperties;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;

/**
 * Snippet that validates values across multiple bindings on change of each
 * observable. If the values of the target observables are not equal the model
 * is not updated. When the values are equal they will be written to sysout.
 *
 * @author Brad Reynolds
 */
public class Snippet011ValidateMultipleBindingsSnippet {
    public static void main(String[] args) {
        Realm.runWithDefault(DisplayRealm.getRealm(Display.getDefault()),
                () -> Snippet011ValidateMultipleBindingsSnippet.run());
    }

    private static void run() {
        Shell shell = new Shell();

        View view = new View(shell);
        final Model model = new Model();

        DataBindingContext dbc = new DataBindingContext();
        dbc.bindValue(WidgetProperties.text(SWT.Modify).observe(view.text1), model.value1,
                new UpdateValueStrategy<String, String>()
                        .setAfterConvertValidator(new CrossFieldValidator(model.value2)),
                null);

        dbc.bindValue(WidgetProperties.text(SWT.Modify).observe(view.text2), model.value2,
                new UpdateValueStrategy<String, String>()
                        .setAfterConvertValidator(new CrossFieldValidator(model.value1)),
                null);

        // DEBUG - print to show value change
        model.value1.addValueChangeListener(event -> System.out.println("Value 1: " + model.value1.getValue()));

        // DEBUG - print to show value change
        model.value2.addValueChangeListener(event -> System.out.println("Value 2: " + model.value2.getValue()));

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

    /**
     * @since 3.2
     *
     */
    private static final class CrossFieldValidator implements IValidator<String> {
        /**
         *
         */
        private final IObservableValue<String> other;

        /**
         * @param model
         */
        private CrossFieldValidator(IObservableValue<String> other) {
            this.other = other;
        }

        @Override
        public IStatus validate(String value) {
            if (!value.equals(other.getValue())) {
                // DEBUG - print validation result
                System.out.println("Validation fine");
                return ValidationStatus.ok();
            }
            // DEBUG - print validation result
            System.out.println("Validation error: values cannot be the same");
            return ValidationStatus.error("values cannot be the same");
        }
    }

    static class Model {
        WritableValue<String> value1 = new WritableValue<>();
        WritableValue<String> value2 = new WritableValue<>();
    }

    static class View {
        Text text1;
        Text text2;

        View(Composite composite) {
            composite.setLayout(new GridLayout(2, true));
            text1 = new Text(composite, SWT.BORDER);
            text2 = new Text(composite, SWT.BORDER);
        }
    }
}