JSON data deserialization

Question

I get this JSON data from front-end:

user    {"idUser":5,"fullname":"Bob Marley", "birthday":"1990-12-14", "login":"b.marley", "password":"none","dateCreate":"2014-10-09 15:01","grp":{"idGrp":"2","nameGrp":"client"}}

I want to do deserialization these data in java:

User.java

public class User implements Serializable {
    private static final long serialVersionUID = 1L;
    private int idUser;
    private String fullname;
    private Date birthday;
    private String login;
    private String password;
    private Date dateCreate;
    private Grp grp;
    //getters and setters

UserDeserializer.java

public class UserDeserializer implements JsonDeserializer<User> {

    @Override
    public User deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
        JsonObject jObject = json.getAsJsonObject();
        User user = new User();
        user.setIdUser(jObject.get("idUser").getAsInt());
        user.setFullname(jObject.get("fullname").getAsString());

        try {
            Date birthday = new SimpleDateFormat("yyyy-MM-dd").parse(jObject.get("birthday").getAsString());
            user.setBirthday(birthday);
        } catch (ParseException e) {
        }

        user.setLogin(jObject.get("login").getAsString());
        user.setPassword(jObject.get("password").getAsString());

        try {
            Date dateCreate = new SimpleDateFormat("yyyy-MM-dd HH:mm").parse(jObject.get("dateCreate").getAsString());
            user.setDateCreate(dateCreate);
        } catch (ParseException e) {
        }

        Grp grp = context.deserialize(jObject.get("grp"), Grp.class);
        user.setGrp(grp);    
        return user;
    }
}

UserEdit.java

public class UserEdit extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
        GsonBuilder gsonBuilder = new GsonBuilder();
        gsonBuilder.registerTypeAdapter(User.class, new UserDeserializer());
        Gson gson = new GsonBuilder().create();
        User user = gson.fromJson(request.getParameter("user"), User.class);

And I get this error at the last row of the UserEdit.java:

04-Nov-2014 21:30:44.003 SEVERE [http-apr-8080-exec-1] org.apache.catalina.core.StandardWrapperValve.invoke Servlet.service() for servlet [Servlet UserEdit] in context with path [] threw exception com.google.gson.JsonSyntaxException: 1990-12-14 at com.google.gson.internal.bind.DateTypeAdapter.deserializeToDate(DateTypeAdapter.java:81) at com.google.gson.internal.bind.DateTypeAdapter.read(DateTypeAdapter.java:66) at com.google.gson.internal.bind.DateTypeAdapter.read(DateTypeAdapter.java:41) at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:95) at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:183) at com.google.gson.Gson.fromJson(Gson.java:805) at com.google.gson.Gson.fromJson(Gson.java:770) at com.google.gson.Gson.fromJson(Gson.java:719) at com.google.gson.Gson.fromJson(Gson.java:691) at com.gmail.zigfridus.UserEdit.doGet(UserEdit.java:24) at javax.servlet.http.HttpServlet.service(HttpServlet.java:618) at javax.servlet.http.HttpServlet.service(HttpServlet.java:725) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:301) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:136) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:74) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:526) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1017) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:652) at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:277) at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2451) at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2440) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:722) Caused by: java.text.ParseException: Unparseable date: "1990-12-14" at java.text.DateFormat.parse(DateFormat.java:357) at com.google.gson.internal.bind.DateTypeAdapter.deserializeToDate(DateTypeAdapter.java:79) ... 32 more

It says that error is because of birthday date, but that date looks like normal.

Please, help me.

The user at the beginning of the JSON user {"idUser":5, makes this ill-formed JSON. Is there really a user at the beginning? — Jonathan M
– Jonathan M, Commented Nov 4, 2014 at 19:56
@Vinze: which one exactly are you referring to, that deals with "any problem"? — njzk2
– njzk2, Commented Nov 4, 2014 at 20:00
@zigfridus are you sure your deserialize method is called? — njzk2
– njzk2, Commented Nov 4, 2014 at 20:01
@JonathanM Yes, there is really user at the beginning: http://localhost:8080/UserEdit?user=%7B%22idUser%22%3A5%2C%22... — Valentyn Grygoriev
– Valentyn Grygoriev, Commented Nov 4, 2014 at 20:04
@njzk2 I wrongly read the question, I think... removed my comment. No entry of the stack seems in user code, so it may be a misuse of the API... — Vinze
– Vinze, Commented Nov 4, 2014 at 20:12

njzk2 · Accepted Answer · 2014-11-04 20:20:22Z

2

Here :

GsonBuilder gsonBuilder = new GsonBuilder();
gsonBuilder.registerTypeAdapter(User.class, new UserDeserializer());
Gson gson = new GsonBuilder().create();

You are creating a new GsonBuilder, effectively dismissing the one you just configured. Use

GsonBuilder gsonBuilder = new GsonBuilder();
gsonBuilder.registerTypeAdapter(User.class, new UserDeserializer());
Gson gson = gsonBuilder.create();

to use the gsonBuilder configured with the user deserializer.

answered Nov 4, 2014 at 20:20

njzk2

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1 Comment

Valentyn Grygoriev Over a year ago

It was a really stupid mistake. How I didn't see it, I don't understand... Thank You very much for your help! )

Keith Enlow · Accepted Answer · 2014-11-04 19:59:58Z

1

Use yyyy-MM-dd HH:mm:ss as your simple date format. I know you don't have hours, minutes and seconds, but I don't believe that it accepts it without them.

answered Nov 4, 2014 at 19:59

Keith Enlow

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Valentyn Grygoriev Over a year ago

I added dummy time to the birthday: "birthday":"1990-12-14 17:08:44". But it didn't help. I got the same error: com.google.gson.JsonSyntaxException: 1990-12-14 17:08:44

Keith Enlow Over a year ago

Try not adding the dummy time. It will come out zeroes, but It should do the correct format on its own.

CLcoder · Accepted Answer · 2014-11-04 20:15:24Z

1

You will need to add values for hh:mm:ss in order to instantiate an acceptable date format. You obviously aren't concerned with the time and in this case I would suggest simply using 00:00:00.

answered Nov 4, 2014 at 20:15

CLcoder

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Vinze · Accepted Answer · 2014-11-04 20:16:15Z

1

The error seems the use of DateTypeAdapter in the API internal bind... I'm not familiar with this library but maybe your UserDeserializer is not correctly configured in the API/framework and default one is used (and birthday is Date in the bean to deserialize)

answered Nov 4, 2014 at 20:16

Vinze

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