Converting BLOB to ArrayList?

Question

Oracle

Good day
When unloading an ArrayList from the database, an error occurs.
Error on the third line. ArrayList has been saved correctly.
java.io.EOFException is the only thing that is caught during debugging, there are no details, during normal operation the console does not display errors.

while (resultSet.next()) {
                Blob obj = resultSet.getBlob("DECK");
                ObjectInputStream obin2 = new ObjectInputStream(obj.getBinaryStream());

                ArrayList<CabinetSquad> decka = (ArrayList<CabinetSquad>) obin2.readObject();
                String name = resultSet.getString("NAME");
                String description = resultSet.getString("DESCRIPTION");
                Deck deck = new Deck(decka, name, description);
                Decks.add(deck);
            }
        } catch (SQLException | ClassNotFoundException | IOException e) {
            e.printStackTrace();
        }

Please help me understand what the error is and extract the value from the BLOB.

Answer 1

Here is a working example. There is only one condition, the CabinetSquad class must inherit the Serializable interface.

List<CabinetSquad> list = new ArrayList<CabinetSquad>(Arrays.asList(

    new CabinetSquad("a", 1), new CabinetSquad("b", 2), new CabinetSquad("c", 3)

    ));

    ByteArrayOutputStream bout = new ByteArrayOutputStream();

    ObjectOutputStream ooStream = new ObjectOutputStream(bout);
    try {
      ooStream.writeObject(list);
    } finally {
      try {
        ooStream.close();
      } catch (IOException e) {
        e.printStackTrace();
      }
    }

    byte[] byteArray = bout.toByteArray();

    // ----------------------------------

    Connection con = dataSource.getConnection();
    try {

      Statement s = con.createStatement();
      s.executeUpdate("CREATE TABLE ARRAY_LIST (id int not null primary key, list blob not null)");
      s.close();

      // -----------------------------

      PreparedStatement p = con.prepareStatement("INSERT INTO ARRAY_LIST VALUES (?,?)");
      p.setInt(1, 1);
      p.setBlob(2, new ByteArrayInputStream(byteArray));
      p.executeUpdate();
      p.close();

      // ------------------------------------------------

      PreparedStatement p2 = con.prepareStatement("SELECT list FROM ARRAY_LIST WHERE id = ?");

      p2.setInt(1, 1);

      ResultSet rs = p2.executeQuery();

      if (rs.next()) {

        Blob blob = rs.getBlob("list");

        ObjectInputStream objectInputStream = new ObjectInputStream(blob.getBinaryStream());
        try {

          List<CabinetSquad> recoverList = (List<CabinetSquad>) objectInputStream.readObject();

          for (CabinetSquad sc : recoverList) {
            System.out.println(sc);
          }

        } finally {
          try {
            objectInputStream.close();
          } catch (Exception e) {
            e.printStackTrace();
          }
        }

      }

      rs.close();
      p2.close();

    } finally {
      try {
        con.close();
      } catch (SQLException e) {
        e.printStackTrace();
      }
    }