Java +db4o

public static void listaClientes() {
   Cliente cli = new Cliente(null,0);
   ObjectSet result = db.queryByExample(cli);

    while(result.hasNext()) {
        System.out.println(result.next());
    }
}

public ArrayList retornaTodos() {
        ArrayList clientes = new ArrayList();
        ObjectSet lista = db.queryByExample(new Cliente());
        while (lista.hasNext()) {
            Cliente c = (Cliente) lista.next();
            clientes.add(c);
        }
        return clientes;
    }