Deserializing JSON to LocalDate

[Daniel Demesmaecker]

I'm not sure in what forum to post...
I'm trying to help an other poster here on the forum, I managed to figure out what is going wrong, he has a textfile containing jsonobjects, each of those objects contains a date.
When trying to read the file I get this error:

Caused by: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 17
	at com.google.gson.stream.JsonReader.expect(JsonReader.java:339)
	at com.google.gson.stream.JsonReader.beginObject(JsonReader.java:322)
	at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:165)
	... 70 more

In my search what could cause the error I saw a remark of someone that he got the error because he didn't deserialize the date in the jsonObject.
When I remove the date, the error is gone, so in this case that's most likely also the prob.
I've never deserialized anything, how would you do that?

[Ron McLeod]

It would be helpful to see the JSON-encoded representation and the code being used to de-serialize.

[Daniel Demesmaecker]

There isn't any code to deserialize yet... I wouldn't even know how to start
These are the jsonObjects:

{"date":2019-01-07,"score":"55","userName":"Daniel"}
{"date":2019-01-07,"score":"10","userName":"Joske"}
{"date":2019-01-07,"score":"25","userName":"Marie"}
{"date":2019-01-07,"score":"32","userName":"Anneleen"}
{"date":2019-01-07,"score":"13","userName":"Pieter"}
{"date":2019-01-07,"score":"32","userName":"Lisa"}
{"date":2019-01-07,"score":"15","userName":"Mike"}
{"date":2019-01-07,"score":"38","userName":"Jana"}

and this is what I'm using to read the files:

private void readFile() throws IOException {
    BufferedReader br = null;
    try {
        br = new BufferedReader(new FileReader(new File("C:\\Users\\ufotje\\Documents\\highscore.txt")));
    } catch (FileNotFoundException e) {
       e.printStackTrace();
    }
    if (br != null) {
        String st;
        while ((st = br.readLine()) != null) {
            System.out.println(st);
            addPlayerToList(new GsonBuilder().create().fromJson(st, Player.class));
         }
    }
}

[Rob Spoor]

Your dates aren't strings, but numerical calculations. That's not allowed in JSON. You need to put your dates between double quotes as well.

[Daniel Demesmaecker]

I didn't write the json myself it's created

private void createJsonObject() {
    JSONObject obj = new JSONObject();
    obj.put("date", LocalDate.now());
    obj.put("userName", userName.getText());
    obj.put("score", points.getText());
    savePlayer(obj);
}

private void savePlayer(JSONObject obj) {
    try (BufferedWriter file = new BufferedWriter(new FileWriter("/Users/ufotje/Documents/highscore.txt", true))) {
        file.write(obj.toJSONString());
        file.newLine();
        file.flush();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
       points.setText(null);
       userName.setText(null);
    }
}

I added this to my playerClass:

    @JsonDeserialize(using = LocalDateDeserializer.class)
    @JsonSerialize(using = LocalDateSerializer.class)
    private LocalDate date;

but I still get the same error, even when I put my date between double quotes

[Tim Holloway]

That doesn't look like a legal JSON stream anyway. More valid would be:
"data": [  {"date":2019-01-07,"score":"55","userName":"Daniel"},  {"date":2019-01-07,"score":"10","userName":"Joske"},  {"date":2019-01-07,"score":"25","userName":"Marie"},  {"date":2019-01-07,"score":"32","userName":"Anneleen"},  {"date":2019-01-07,"score":"13","userName":"Pieter"},  {"date":2019-01-07,"score":"32","userName":"Lisa"},  {"date":2019-01-07,"score":"15","userName":"Mike"},  {"date":2019-01-07,"score":"38","userName":"Jana"}, ]

Otherwise you have a collection of JSON snippets that are valid at the unit level but not valid as a JSON stream.

[Daniel Demesmaecker]

It's not supossed to be seen as a collection, but all seperate jsonobjects.
Everytime the player ends a game a line is being added

[Tim Holloway]

OK. I missed that. But we need your latest stacktrace. The only one we have is where it choked on not quoting the date strings. Which, alas, I forgot to add to my own example.

[Daniel Demesmaecker]

Maybe I should post a new question cause I maded some changes a and now the subjectline dosn't really cover my question anymore?!
I removed the LocalDate from my PlayerClass and save it now as a string.
but it seems that my jsonObject isn't bindded corectly to the javaObject, cause I'm getting nullpointers.
I'll post the whole code to make it a bit easier for you guys to help.

PlayerClass:

public class Player {
    private String name;
    private String score;
    private String date;

    public Player(String name, String score, String date) {
        this.name = name;
        this.score = score;
        this.date = date;
    }

    public String getName() {
        return name;
    }

    public String getScore() {
        return score;
    }

    public String getDate() {
        return date;
    }
}

MenuController:

public class MenuController {
     @FXML
    private BorderPane bPane;

    @FXML
    private void setAdd() throws IOException {
        setCenter("add.fxml");
    }

    private void setCenter(String resource) throws IOException {
        FXMLLoader loader = new FXMLLoader();
        loader.setLocation(Main.class.getResource(resource));
        BorderPane newScene = loader.load();
        bPane.setCenter(newScene);
    }
    
    @FXML
    private void show() throws IOException {
        setCenter("view.fxml");
    }
}

AddController:

public class AddController {
    @FXML
    private TextField userName, points;

    @FXML
    private void addPlayer() {
        createJsonObject();
    }

    private void createJsonObject() {
        JSONObject obj = new JSONObject();
        obj.put("date", "" + LocalDate.now());
        obj.put("userName", userName.getText());
        obj.put("score", points.getText());
        savePlayer(obj);
    }

    private void savePlayer(JSONObject obj) {
        try (BufferedWriter file = new BufferedWriter(new FileWriter("pathToFile.txt", true))) {
            file.write(obj.toJSONString());
            file.newLine();
            file.flush();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            points.setText(null);
            userName.setText(null);
        }
    }

}

ShowController:

public class ShowController {
    private ObservableList<Player> players = observableArrayList();
    @FXML
    private TableView<Player> table;
    @FXML
    private TableColumn<Player, String> nameCol;
    @FXML
    private TableColumn<Player, String> scoreCol;

    @FXML
    private void initialize() throws IOException {
        BufferedReader br = null;
        try {
            br = new BufferedReader(new FileReader(new File("pathToFile.txt")));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        if (br != null) {
            String st;
            while ((st = br.readLine()) != null) {
                System.out.println(st);
                addPlayerToList(new GsonBuilder().create().fromJson(st, Player.class));

            }
        }
    }

    private void addPlayerToList(Player player) {
        players.add(player);
        setTable();
    }

    private void setTable() {
        nameCol.setCellValueFactory(new PropertyValueFactory<>("name"));
        scoreCol.setCellValueFactory(new PropertyValueFactory<>("score"));
        table.setItems(players);
    }
}

Stacktrace:

Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
	at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1774)
	at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1657)
	at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
	at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
	at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
	at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
	at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
	at javafx.event.Event.fireEvent(Event.java:198)
	at javafx.scene.Node.fireEvent(Node.java:8411)
	at javafx.scene.control.Button.fire(Button.java:185)
	at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182)
	at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96)
	at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
	at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
	at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
	at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
	at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
	at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
	at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
	at javafx.event.Event.fireEvent(Event.java:198)
	at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
	at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
	at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
	at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
	at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:394)
	at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
	at java.security.AccessController.doPrivileged(Native Method)
	at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$353(GlassViewEventHandler.java:432)
	at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
	at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:431)
	at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
	at com.sun.glass.ui.View.notifyMouse(View.java:937)
	at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
	at com.sun.glass.ui.win.WinApplication.lambda$null$147(WinApplication.java:177)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
	at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
	at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1771)
	... 52 more
Caused by: java.lang.NullPointerException
	at sample.Controller.setTable(Controller.java:79)
	at sample.Controller.addPlayerToList(Controller.java:75)
	at sample.Controller.readFile(Controller.java:66)
	at sample.Controller.show(Controller.java:52)
	... 62 more

[Daniel Demesmaecker]

Lol weird as hell... Before, cause it was ment as an quick example, aal the code was in my sample.Controller.
I knew if I would have posted it that way here, surely someone would a remark about it, so I sperated my code a bit.
I ran it again to see if the rest still worked and now everything works!?
At least allmost, no errors anymore, but the nameColumn isn't filled yet

[Daniel Demesmaecker]

I also managed to figure that out, in my object I was referring to userName, but the instance variable is name, so I changed the instance variable and adjusted the propertyValueFactory and tada