Tutorial

JFace contains additional Dialogs which are more flexible then the SWT Dialogs It provides static methods to open commonly used dialogs.

You can for example use the MessageDialog class which allows to customize the Buttons which should be used.

MessageDialog provides also static methods to open commonly used Dialogs, e.g. an info or a warning Dialog.

				
// Customized MessageDialog with configured buttons
MessageDialog dialog = new MessageDialog(shell, "My Title", null,
    "My message", MessageDialog.ERROR, new String[] { "First",
	"Second", "Third" }, 0);
int result = dialog.open();
System.out.println(result);

// A few standard message dialog
MessageDialog.openConfirm(shell, "Confirm", "Please confirm");
MessageDialog.openError(shell, "Error", "Error occured");
MessageDialog.openInformation(shell, "Info", "Info for you");
MessageDialog.openQuestion(shell, "Question", "Really, really?");
MessageDialog.openWarning(shell, "Warning", "I warn you");

			

JFace also provides the ErrorDialog class which allows to report a Status object. Status objects are frequently used in Eclipse to report errors.

The org.eclipse.jface.dialogs.Dialog class can be extend to create own simple Dialogs. This class creates a simple area in which you can place controls and add an OK and Cancel button to it.

Your class needs to implement have createDialogArea method. This methods gets an Composites which expects to get a GridData object assigned as its layout data. Via the super.createDialogArea(parent) mehod call, you can get an Composite to which you can add your controls.

You can also define your own Dialogs based on the TitleAreaDialog class.

TitleAreaDialog has a reserved space for providing feedback to the user. You can set the text in this space via the setMessage() and setErrorMessage() methods.

The following shows an example for a custom defined TitleAreaDialog and shows how to open this dialog.

				
package de.vogella.rcp.intro.dialogs.custom.dialogs;

import org.eclipse.jface.dialogs.IMessageProvider;
import org.eclipse.jface.dialogs.TitleAreaDialog;
import org.eclipse.jface.resource.JFaceResources;
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.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;

public class MyDialog extends TitleAreaDialog {

	private Text firstNameText;
	private Text lastNameText;
	private String firstName;
	private String lastName;

	public MyDialog(Shell parentShell) {
		super(parentShell);
	}

	@Override
	public void create() {
		super.create();
		// Set the title
		setTitle("This is my first own dialog");
		// Set the message
		setMessage("This is a TitleAreaDialog", IMessageProvider.INFORMATION);

	}

	@Override
	protected Control createDialogArea(Composite parent) {
		GridLayout layout = new GridLayout();
		layout.numColumns = 2;
		// layout.horizontalAlignment = GridData.FILL;
		parent.setLayout(layout);

		// The text fields will grow with the size of the dialog
		GridData gridData = new GridData();
		gridData.grabExcessHorizontalSpace = true;
		gridData.horizontalAlignment = GridData.FILL;

		Label label1 = new Label(parent, SWT.NONE);
		label1.setText("First Name");

		firstNameText = new Text(parent, SWT.BORDER);
		firstNameText.setLayoutData(gridData);
		
		Label label2 = new Label(parent, SWT.NONE);
		label2.setText("Last Name");
		// You should not re-use GridData
		gridData = new GridData();
		gridData.grabExcessHorizontalSpace = true;
		gridData.horizontalAlignment = GridData.FILL;
		lastNameText = new Text(parent, SWT.BORDER);
		lastNameText.setLayoutData(gridData);
		return parent;
	}

	@Override
	protected void createButtonsForButtonBar(Composite parent) {
		GridData gridData = new GridData();
		gridData.verticalAlignment = GridData.FILL;
		gridData.horizontalSpan = 3;
		gridData.grabExcessHorizontalSpace = true;
		gridData.grabExcessVerticalSpace = true;
		gridData.horizontalAlignment = SWT.CENTER;

		parent.setLayoutData(gridData);
		// Create Add button
		// Own method as we need to overview the SelectionAdapter
		createOkButton(parent, OK, "Add", true);
		// Add a SelectionListener

		// Create Cancel button
		Button cancelButton = createButton(parent, CANCEL, "Cancel", false);
		// Add a SelectionListener
		cancelButton.addSelectionListener(new SelectionAdapter() {
			public void widgetSelected(SelectionEvent e) {
				setReturnCode(CANCEL);
				close();
			}
		});
	}

	protected Button createOkButton(Composite parent, int id, String label,
			boolean defaultButton) {
		// increment the number of columns in the button bar
		((GridLayout) parent.getLayout()).numColumns++;
		Button button = new Button(parent, SWT.PUSH);
		button.setText(label);
		button.setFont(JFaceResources.getDialogFont());
		button.setData(new Integer(id));
		button.addSelectionListener(new SelectionAdapter() {
			public void widgetSelected(SelectionEvent event) {
				if (isValidInput()) {
					okPressed();
				}
			}
		});
		if (defaultButton) {
			Shell shell = parent.getShell();
			if (shell != null) {
				shell.setDefaultButton(button);
			}
		}
		setButtonLayoutData(button);
		return button;
	}

	private boolean isValidInput() {
		boolean valid = true;
		if (firstNameText.getText().length() == 0) {
			setErrorMessage("Please maintain the first name");
			valid = false;
		}
		if (lastNameText.getText().length() == 0) {
			setErrorMessage("Please maintain the last name");
			valid = false;
		}
		return valid;
	}
	
	@Override
	protected boolean isResizable() {
		return true;
	}

	// We need to have the textFields into Strings because the UI gets disposed
	// and the Text Fields are not accessible any more.
	private void saveInput() {
		firstName = firstNameText.getText();
		lastName = lastNameText.getText();

	}

	@Override
	protected void okPressed() {
		saveInput();
		super.okPressed();
	}

	public String getFirstName() {
		return firstName;
	}

	public String getLastName() {
		return lastName;
	}
}

			

This Dialog can get called via:

				
MyDialog dialog = new MyDialog(shell);
dialog.create();
if (dialog.open() == Window.OK) {
	System.out.println(dialog.getFirstName());
	System.out.println(dialog.getLastName());
}

			

Eclipse provides several standard selection Dialogs in Eclipse 3.x. In Eclipse 3.x you can directly use them, in Eclipse 4.x you may have to copy them into your plug-in and modify them slightly. I still list them here, so that you can use their coding as examples.

These Dialogs and other useful functionality might be moved to make them directly usable in Eclipse 4. See Strategy for porting useful org.eclipse.ui.* bits for Eclipse4 RCP apps Bug report for details.

Here is a list of these Dialogs.

For example ElementListSelectionDialog allows to select elements from a list where the dialog provides a filter for the elements.

				
ElementListSelectionDialog dialog = new ElementListSelectionDialog(
		shell, new LabelProvider());
dialog.setElements(new String[] { "Linux", "Mac", "Windows" });
dialog.setTitle("Which operating system are you using");
// User pressed cancel
if (dialog.open() != Window.OK) {
		return false;
}
Object[] result = dialog.getResult();
			

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