Data Binding with SWT controls

3.1. RCP project

Create a new Eclipse RCP project "de.vogella.databinding.person.swt" use "Hello RCP" as a template (see Create your first Eclipse RCP application for details).

3.2. Model dependencies

Add the plugin "de.vogella.databinding.person.model" as a dependency to your plugin.

3.3. Eclipse Databinding dependencies

Add the plugins "org.eclipse.core.databinding", "org.eclipse.core.databinding.beans", "org.eclipse.jface.databinding" and "org.eclipse.core.databinding.property" as a dependency to your plugin.

3.4. UserInterface

Add via extension a view to the RCP application and create the class "de.vogella.databinding.person.PersonView" for this view.

Add the view to the perspective.

See Eclipse RCP Tutorial for details). Use the "Hello RCP" as a template.

Then implement the following code.

    
package de.vogella.databinding.person.swt;

import org.eclipse.core.databinding.DataBindingContext;
import org.eclipse.core.databinding.beans.BeanProperties;
import org.eclipse.core.databinding.beans.BeansObservables;
import org.eclipse.core.databinding.observable.value.IObservableValue;
import org.eclipse.jface.databinding.swt.SWTObservables;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Combo;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Layout;
import org.eclipse.swt.widgets.Text;
import org.eclipse.ui.part.ViewPart;

import de.vogella.databinding.person.model.Address;
import de.vogella.databinding.person.model.Person;

public class PersonView extends ViewPart {
 public static final String ID = "de.vogella.databinding.person.swt.View";
 private Person person;

 private Text firstName;
 private Text ageText;
 private Button marriedButton;
 private Combo genderCombo;
 private Text countryText;

 public PersonView() {
 }

 @Override
 public void createPartControl(Composite parent) {

  person = new Person();
  Address address = new Address();
  address.setCountry("Deutschland");
  person.setAddress(address);
  person.setFirstName("John");
  person.setLastName("Doo");
  person.setGender("Male");
  person.setAge(12);
  person.setMarried(true);
  // Lets put thing to order
  Layout layout = new GridLayout(2, false);
  parent.setLayout(layout);

  Label firstLabel = new Label(parent, SWT.NONE);
  firstLabel.setText("Firstname: ");
  firstName = new Text(parent, SWT.BORDER);

  GridData gridData = new GridData();
  gridData.horizontalAlignment = SWT.FILL;
  gridData.grabExcessHorizontalSpace = true;
  firstName.setLayoutData(gridData);

  Label ageLabel = new Label(parent, SWT.NONE);
  ageLabel.setText("Age: ");
  ageText = new Text(parent, SWT.BORDER);

  gridData = new GridData();
  gridData.horizontalAlignment = SWT.FILL;
  gridData.grabExcessHorizontalSpace = true;
  ageText.setLayoutData(gridData);

  Label marriedLabel = new Label(parent, SWT.NONE);
  marriedLabel.setText("Married: ");
  marriedButton = new Button(parent, SWT.CHECK);

  Label genderLabel = new Label(parent, SWT.NONE);
  genderLabel.setText("Gender: ");
  genderCombo = new Combo(parent, SWT.NONE);
  genderCombo.add("Male");
  genderCombo.add("Female");

  Label countryLabel = new Label(parent, SWT.NONE);
  countryLabel.setText("Country");
  countryText = new Text(parent, SWT.BORDER);

  Button button1 = new Button(parent, SWT.PUSH);
  button1.setText("Write model");
  button1.addSelectionListener(new SelectionAdapter() {

   @Override
   public void widgetSelected(SelectionEvent e) {
    System.out.println("Firstname: " + person.getFirstName());
    System.out.println("Age " + person.getAge());
    System.out.println("Married: " + person.isMarried());
    System.out.println("Gender: " + person.getGender());
    System.out.println("Country: "
      + person.getAddress().getCountry());
   }
  });

  Button button2 = new Button(parent, SWT.PUSH);
  button2.setText("Change model");
  button2.addSelectionListener(new SelectionAdapter() {
   @Override
   public void widgetSelected(SelectionEvent e) {
    person.setFirstName("Lars");
    person.setAge(person.getAge() + 1);
    person.setMarried(!person.isMarried());
    if (person.getGender().equals("Male")) {

    } else {
     person.setGender("Male");
    }
    if (person.getAddress().getCountry().equals("Deutschland")) {
     person.getAddress().setCountry("USA");
    } else {
     person.getAddress().setCountry("Deutschland");
    }
   }
  });

  // Now lets do the binding
  bindValues();
 }

 @Override
 public void setFocus() {
 }

 private void bindValues() {
  // The DataBindingContext object will manage the databindings
  DataBindingContext bindingContext = new DataBindingContext();
  IObservableValue uiElement;
  IObservableValue modelElement;
  // Lets bind it
  uiElement = SWTObservables.observeText(firstName, SWT.Modify);
  modelElement = BeansObservables.observeValue(person, "firstName");
  // The bindValue method call binds the text element with the model
  bindingContext.bindValue(uiElement, modelElement, null, null);

  uiElement = SWTObservables.observeText(ageText, SWT.Modify);
  modelElement = BeansObservables.observeValue(person, "age");
  // Remember the binding so that we can listen to validator problems
  // See below for usage
  bindingContext.bindValue(uiElement, modelElement, null, null);

  uiElement = SWTObservables.observeSelection(marriedButton);
  modelElement = BeansObservables.observeValue(person, "married");

  bindingContext.bindValue(uiElement, modelElement, null, null);

  uiElement = SWTObservables.observeSelection(genderCombo);
  modelElement = BeansObservables.observeValue(person, "gender");

  bindingContext.bindValue(uiElement, modelElement, null, null);

  // Address field is bound to the Ui
  uiElement = SWTObservables.observeText(countryText, SWT.Modify);
  modelElement = BeanProperties.value("address.country").observe(person);
  bindingContext.bindValue(uiElement, modelElement, null, null);

 }

}

   

The DataBindingContext object will manage the databindings. The bindValue method call binds the text element with the model. The first parameter is the UIElement with an update strategy (which defines then the update should take place) wrapped into a IObservableValue object, the second one does the same for the model object and the last parameter can be used to pass validators and converters to the binding. By passing null you get the default ones.

3.5. Run

Run the example and test it. Each time you change the UI element then model changes automatically. If you change the model then the UI will also update.

The coding also demonstrate that Eclipse Databinding converts per default already the from the typical values and that it performs in standard already nice validation.