JAVA SWT comment recup valeur d'un champ Text

public class Client {

public static void main (String [] args) {
	Display display = new Display ();
	Shell shell = new Shell (display);
	
	final Text text = new Text (shell, SWT.BORDER);
	text.setLayoutData (new RowData (100, SWT.DEFAULT));
	
	
	String s;
	
	Button ok = new Button (shell, SWT.PUSH);
	ok.setText ("calibrate WiFi");
	ok.addSelectionListener(new SelectionAdapter() {
		public void widgetSelected(SelectionEvent e) {
			s=text.getText();
			
		}
	});
	
	shell.setLayout (new RowLayout ());
	shell.pack ();
	shell.open ();
	while (!shell.isDisposed ()) {
		if (!display.readAndDispatch ()) display.sleep ();
	}
	display.dispose ();
}
}