SWT: A Developer's Notebook

Using the Group Class

The SWT Group class extends the Composite class and provides some additional functionality related primarily to the appearance of the group. Group permits you to add a text label as a prompt to the user of group contents and to change the border style of the resulting object, yielding more of a visual indication to the user that the widgets are part of a functional area of the application.

Because the Group class cannot be subclassed, it must be used in a manner similar to Shell—you create an instance of Group within another container class (such as Composite) and then add widgets to that instance.

How do I do that?

The task of creating a Group is very similar to the task of creating a Shell. First, create a Composite that will serve as the container for the Group, as shown in Example 10-4.

Example 10-4. Using a Group

import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.*;
import org.eclipse.swt.SWT;

public class GroupExample extends Composite {
    
    final Button b1;
    final Button b2;
    final Button b3;
    
    public GroupExample(Composite c, int style)
    {
        super(c, SWT.NO_BACKGROUND );
        this.setSize(110, 75);
        this.setLayout(new FillLayout( ));
        final Group g = new Group(this, style);
        g.setSize(110, 75);
        g.setText("Options Group");
        b1 = new Button(g, SWT.RADIO);
        b1.setBounds(10,20,75, 15);
        b1.setText("Option One");
        b2 = new Button(g, SWT.RADIO);
        b2.setBounds(10,35,75, 15);
        b2.setText("Option Two");
        b3 = new Button(g, SWT.RADIO);
        b3.setBounds(10,50,80, 15);