SWT Java Tutorial

A typed listener can be used to listen for only one particular typed event.
For example, SelectionListener is a typed listener for event SelectionEvent.
Untyped event listeners offer a generic, low-level mechanism to listen for events.

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.events.SelectionListener;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
public class GenericEventUntyped {
  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setLayout(new GridLayout());
    Button button = new Button(shell, SWT.NONE);
    button.setText("Click and check the console");
    button.addSelectionListener(new SelectionListener() {
      public void widgetSelected(SelectionEvent arg0) {
        System.out.println("widgetSelected");
      }
      public void widgetDefaultSelected(SelectionEvent arg0) {
        System.out.println("widgetDefaultSelected");
      }
    });
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        display.sleep();
      }
    }
  }
}