public static void main(String[] args)
    {
        Avion a1 = new Avion("Boeing", "777X", "comercial" , 384);
        Avion a2 = new Avion("Boeing", "F-18", " caza polivalente" , 1);

        File file = new File("file2.dat");
        boolean append = file.exists(); // if file exists then append, otherwise create new

        try
        {
            FileOutputStream fout = new FileOutputStream(file, append);
            AppendableObjectOutputStream oout = new AppendableObjectOutputStream(fout, append);
            oout.writeObject(a1);
            oout.writeObject(a2);
            mostrarArchivo("file2.dat");
        }
        catch (EOFException e)
        {
            //es un error pero no pasa nada
        }
        catch (FileNotFoundException e)
        {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }


    }