ok ho risolto :-) thank you!!

codice:
class MyActionListener implements ActionListener
	{


		public void actionPerformed(ActionEvent e) 
		{
			if(list.getSelectedIndex() == 0)
				System.out.println("Riga 1");
			else if(list.getSelectedIndex() == 1)
				System.out.println("Riga 2");
			else if(list.getSelectedIndex() == 2)
				System.out.println("Riga 3");
			else if(list.isSelectionEmpty())
				System.out.println("Nessuna selezione");
		}
		
	}