Listing 1

Button b = new Button(shell,SWT.PUSH);
b.addSelectionListener(
  new SelectionAdapter(){
    public void widgetSelected(
      SelectionEvent e){
// button was selected
    } 
});
b.addFocusListener(
  new FocusAdapter(){
    public void focusGained(
      FocusEvent e){
// button got focus
    }
});

Listing 2

Button b = new Button(shell,SWT.PUSH);
Listener listener = new Listener() {
  public void handleEvent(Event event) {
    switch (event.type) {
      case SWT.Selection:
	  // button was selected
        break;
      case SWT.FocusIn:
  // button got focus
        break;
    }
  }
};
b.addListener(SWT.Selection,listener);
b.addListener(SWT.FocusIn,listener);