Serialization for Java Calendar

Question

How do I create a custom serialization for java Calendar to json by extending json serializer<Calendar>?

I tried the same for java.until.Date and it's working. In the serialization method, I converted Date as String and write it in json format.

The sample code done for java.util.Date is similar to code given below

  public class CDJsonDateSerializer extends JsonSerializer<Date>{
  @Override
  public void serialize(Date date, JsonGenerator jsonGenerator,SerializerProvider provider)
 throws IOException {

      SimpleDateFormat dateFormat = new SimpleDateFormat("MM/dd/yyyy");
      String dateString = dateFormat.format(date);
     jsonGenerator.writeString(dateString);
 }
}

And it is used like so:

 @JsonSerialize(using = CDJsonDateSerializer.class)
 private Date startDate;

What can I do for Serialize Calendar in java to json without losing data in Calendar object ?

Can you post your code. It will be easier to answer if we have something to start with. — talex, Nov 23 '15 at 16:46
if i follow above approach.how will i deserialize back actual Calendar object from string written as json.? For Date to string and viceverca. we have" format and parse " methods — Adarsh Gangaprakash Unnithan, Nov 23 '15 at 17:53
You can parse it to date and then initialize `Calendar` with it like this `c = Calendar.getInstance(); c.setTime(date);`. There is `JsonDeserializer` class for it. — talex, Nov 23 '15 at 18:11

cassiomolin · Accepted Answer · 2015-11-23T18:36:46.670

From JSON to `Calendar`

Create a JsonSerializer:

public class CalendarSerializer extends JsonSerializer<Calendar> {

    private SimpleDateFormat formatter = new SimpleDateFormat("MM/dd/yyyy");

    @Override
    public void serialize(Calendar calendar, JsonGenerator jsonGenerator,
                          SerializerProvider serializerProvider) throws IOException {

        String dateAsString = formatter.format(calendar.getTime());
        jsonGenerator.writeString(dateAsString);

    }
}

And then use it:

@JsonSerialize(using = CalendarSerializer.class)
private Calendar calendar;

From `Calendar` to JSON

Create a JsonDeserializer:

public class CalendarDeserializer extends JsonDeserializer<Calendar> {

    private SimpleDateFormat formatter = new SimpleDateFormat("MM/dd/yyyy");

    @Override
    public Calendar deserialize(JsonParser jsonParser,
                                DeserializationContext deserializationContext) 
                                throws IOException {

        String dateAsString = jsonParser.getText();

        try {
            Date date = formatter.parse(dateAsString);
            Calendar calendar = Calendar.getInstance();
            calendar.setTime(date);
            return calendar;
        } catch (Exception e) {
            throw new IOException(e);
        }
    }

And then use it:

@JsonDeserialize(using = CalendarDeserializer.class)
private Calendar calendar;

You can set the timezone for a Calendar object, but getting a Date object from it using the getTime() method will return a Date object with the host computer's time zone. How to hanle that?Thank you — Adarsh Gangaprakash Unnithan, Nov 23 '15 at 18:56
Is there any issue in handling timezone with this approach ? — Adarsh Gangaprakash Unnithan, Nov 23 '15 at 19:03
@AdarshGangaprakashUnnithan You can add the timezone to your date format if you need. You can use the [ISO 8601](http://stackoverflow.com/q/2201925/1426227) format. — cassiomolin, Nov 23 '15 at 19:14
If you stick to the ISO 8601 format, you can use javax.xml.bind.DatatypeConverter for the conversion. — dimplex, Mar 27 '21 at 11:10

score 0 · Answer 2 · answered Nov 23 '15 at 16:50

0

If the only data you need as json is a date, you can using Gson:

JsonObject albums = new JsonObject();

albums.addProperty("date", new Date());

if your json instead has more than that, you can sonsider to define your own class and serialze it by adding this method to the defined class:

public String toJson() {
        Gson gson = new Gson();

        return gson.toJson(this);
    }

answered Nov 23 '15 at 16:50

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I'm able to do the same using fasterxml by converting java Date to string and write it as json. I don't know how to achieve the same for java Calendar object – Adarsh Gangaprakash Unnithan Nov 23 '15 at 17:08
@AdarshGangaprakashUnnithan, tell me how does the output should look like? – ΦXocę 웃 Пepeúpa ツ Nov 23 '15 at 17:15
I have updated the question with more info.In output i should be able to deserialize back the stored json object to java Calendar – Adarsh Gangaprakash Unnithan Nov 23 '15 at 17:35
@AdarshGangaprakashUnnithan you are almost there, but add as a comment to your question, how does the json with a calendar object must look like? **{"???":"????", "???":"????", "???":"????"}** – ΦXocę 웃 Пepeúpa ツ Nov 23 '15 at 17:38
Now im getting " unrecognized field" error while trying to seralize.so i dnt have the exact json structure for java Calendar field – Adarsh Gangaprakash Unnithan Nov 23 '15 at 17:55

Serialization for Java Calendar

2 Answers2

From JSON to Calendar

From Calendar to JSON

From JSON to `Calendar`

From `Calendar` to JSON