Problem deserializing property 'udate' Date in JAVA

Question

https://i.stack.imgur.com/aaPHR.png

I get date (udate field) in String format from API.

I have DTO class for this. But i need get day like '28.12.2021' for send to user.

public class CardHistoryUtrno {

@JsonDeserialize( using = MyDateDeserializer.class )
@JsonFormat(pattern="yyyyMMdd")
        private Date udate;

Now i take date like this:

https://i.stack.imgur.com/I2oxj.png

MyDateDeserializer.class

public class MyDateDeserializer extends JsonDeserializer {

    @Override
    
    public Object deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException, JacksonException {
        SimpleDateFormat format = new SimpleDateFormat("yyyyMMdd");
       DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyyMMdd");
        String date = jsonParser.getText();
    
    
    
    
        try {
            return format.parse(date);
    
        } catch (ParseException e) {
            throw new RuntimeException(e);
        }
    }

}

How i can get date like DD.MM.YYYY?

Answer 1

public class MyDateDeserializer extends JsonDeserializer {

@Override

public Object deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException, JacksonException {


    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMdd");
    DateTimeFormatter formatter2 = DateTimeFormatter.ofPattern("dd.MM.yyyy");

    String date2 = jsonParser.getText();



    LocalDate localDate = LocalDate.parse(date2, formatter);
 // LocalDate localDate1= LocalDate.parse(formatter2.format(localDate));

    return localDate;

}

I do this and its working. Thanks)

Answer 2

The JsonDeserializer instructs Jackson how to convert a serialized input (in JSON) into an object (a Date).

Specularly, you need to create a JsonSerializer (and annotate the same field with it) in order to serialize the Date object into the format you want. That would be:

public final class TimestampSerializer extends JsonSerializer<Date> {
    private static final DateTimeFormatter DATE_TIME_FORMATTER = DateTimeFormatter.ofPattern("dd.MM.yyyy");

    @Override
    public void serialize(Date date, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
        String str = DATE_TIME_FORMATTER.format(date);
        jsonGenerator.writeString(str);
    }
}    

Suggestion: the class Date is deprecated, prefer something newer such as LocalDate (if you care about the time zone) or Instant (if you want to leave everything at UTC timezone).