Question

Well I have this class for a game I’m making, and I’m trying to save the ArrayList notes. When I logout, it properly print the size, for example if I have 5 notes, when I log out notes.getSize() would be 5, but when I log in, it gets reset back to nothing. Why isn’t notes saving?

public class Notes implements Serializable {

    private static final long serialVersionUID = -4947870743226160329L;
    private ArrayList<Note> notes = new ArrayList<Note>(30);

    public class Note implements Serializable {

        private static final long serialVersionUID = -4589885080580317958L;

        private int color = 0;
        private String text = "";

        public Note(int color, String text) {
            this.setColor(color);
            this.setText(text);
        }

        public void setText(String text) {
            this.text = text;
        }

        public String getText() {
            return text;
        }

        public void setColor(int color) {
            this.color = color;
        }

        public int getColor() {
            return color;
        }
    }

    private transient Player player;

    public Notes(Player p) {
        this.player = p;
    }

    public void addNote(String text) {
        System.out.println("Note Text: "+text);
        if (text.length() > 50) {
            player.getPackets().sendGameMessage("You can only enter notes up to 50 characters!");
            return;
        }
        if (notes.size() < 30) {
            notes.add(new Note(0, text));
        } else {
            player.getPackets().sendGameMessage("You cannot add more then 30 notes!");
            return;
        }
        int NoteId = notes.size() - 1;
        player.getPackets().sendConfig(1439, NoteId);
        player.getTemporaryAttributtes().put("selectedNote", NoteId);
        refreshNotes(false);
    }

    public void addNote(String text, int color) {
        notes.add(new Note(color, text));
    }

    public void loadNotes() {
        player.getPackets().sendIComponentSettings(34, 9, 0, 30, 2621470);
        player.getPackets().sendHideIComponent(34, 3, false);
        player.getPackets().sendHideIComponent(34, 44, false);
        player.getPackets().sendIComponentText(34, 13, "Loading notes<br>Please wait...");
        player.getPackets().sendConfig(1439, -1);
        refreshNotes(true);
    }

    public void refreshNotes(boolean sendStartConfigs) {
        for (int i = 0; i < 30; i++) {
            player.getPackets().sendGlobalString(149 + i, i < notes.size() ? notes.get(i).getText() : "");
        }
        if (sendStartConfigs) {
            for (int i = 1430; i < 1450; i++)
                player.getPackets().sendConfig(i, i);
        }
        player.getPackets().sendConfig(1440, getFirstTotalColorValue());
        player.getPackets().sendConfig(1441, getSecondTotalColorValue());
    }


    public int intColorValue(int color, int noteId) {
        return (int) (Math.pow(4, noteId) * color);
    }

    public int getFirstTotalColorValue() {
        int Color = 0;
        for (int i = 0; i < 15; i++) {
            if (notes.size() > i)
                Color += intColorValue(notes.get(i).getColor(), i);
        }
        return Color;
    }

    public int getSecondTotalColorValue() {
        int color = 0;
        for (int i = 0; i < 15; i++) {
            if (notes.size() > (i + 16))
                color += intColorValue(notes.get(i + 16).getColor(), i);
        }
        return color;
    }

    public void deleteSelectedNote() {
        if ((int)player.getTemporaryAttributtes().get("selectedNote") > -1) {
            int slot = (int) player.getTemporaryAttributtes().get("selectedNote");
            notes.remove(slot);
            player.getTemporaryAttributtes().put("selectedNote", -1);
            player.getPackets().sendConfig(1439, -1);
            refreshNotes(false);
        }
    }

    public void clear() {
        notes.clear();
        refreshNotes(false);
    }

    public void editNote(String string, int index) {
        notes.get(index).setText(string);
        refreshNotes(false);
    }

    public void setColor(int color, int index) {
        notes.get(index).setColor(color);
        refreshNotes(false);
    }

    public void deleteNote(int slot) {
        notes.remove(slot);
        refreshNotes(false);
    }

    public void setNotes(ArrayList<Note> setNotes) {
        notes = setNotes;
        refreshNotes(false);
    }

}

And here is the class I manage saving/loading in

public class SerializableFilesManager {

private static final String PATH = "data/characters/";
private static final String BACKUP_PATH = "data/charactersBackup/";

public synchronized static final boolean containsPlayer(String username) {
    return new File(PATH + username + ".p").exists();
}

public synchronized static Player loadPlayer(String username) {
    try {
        return (Player) loadSerializedFile(new File(PATH + username + ".p"));
    } catch (Throwable e) {
        Logger.handle(e);
    }
    try {
        Logger.log("SerializableFilesManager", "Recovering account: "
                + username);
        return (Player) loadSerializedFile(new File(BACKUP_PATH + username
                + ".p"));
    } catch (Throwable e) {
        Logger.handle(e);
    }
    return null;
}

public static boolean createBackup(String username) {
    try {
        Utils.copyFile(new File(PATH + username + ".p"), new File(
                BACKUP_PATH + username + ".p"));
        return true;
    } catch (Throwable e) {
        Logger.handle(e);
        return false;
    }
}

public synchronized static void savePlayer(Player player) {
    try {
        storeSerializableClass(player, new File(PATH + player.getUsername()
                + ".p"));
    } catch (ConcurrentModificationException e) {
        //happens because saving and logging out same time
    } catch (Throwable e) {
        Logger.handle(e);
    }
}

public static final Object loadSerializedFile(File f) throws IOException,
        ClassNotFoundException {
    if (!f.exists())
        return null;
    ObjectInputStream in = new ObjectInputStream(new FileInputStream(f));
    Object object = in.readObject();
    in.close();
    return object;
}

public static final void storeSerializableClass(Serializable o, File f)
        throws IOException {

    ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(f));
    out.writeObject(o);
    out.close();
}

private SerializableFilesManager() {

}

}

Answer 1

1. Do NOT mark Player as transient, cause you are saving it, transient will prevent if from
   getting saved, and will bring player to the default value of null, when deserialized.

2. Have you made the player class serializable ?

3. Its the Entire object graph that gets serialized or none… the purpose of transient is to make a particular member to be left off during serialization so that, the process of serialization goes smoothly.

4. For example, Suppose in a game we want to keep the progress of the player and hours of play for that session, but not the starting and ending times. So the starting and ending time can be made transient.