Can I override the serializer annotated in @JsonSerialize(using=Serializer1.class)

[chiahao]

public class TestLocalDateTimeWithSerializerBean {

  public TestLocalDateTimeWithSerializerBean(LocalDateTime dateTime) {
    this.dateTime = dateTime;
  }

  @JsonSerialize(using = LocalDateTimeToHHmmssSerializer.class)
  LocalDateTime dateTime;
}

@Test
void givenSerializer_whenBeanHasSerializerAnnotation_thenOverride() throws JsonProcessingException {
  TestLocalDateTimeWithSerializerBean dateBean = new TestLocalDateTimeWithSerializerBean(LocalDateTime.of(1949, 2, 28, 15, 57, 31));

  ObjectMapper mapper = new ObjectMapper().registerModule(new SimpleModule().addSerializer(
    LocalDateTime.class, new LocalDateTimeToHHmmSerializer()
  ));

  String result = mapper.writeValueAsString(dateBean);
  String expResult = "{\"dateTime\":\"15:57:31\"}";
  assertEquals(expResult, result);
}

I've already annotate dateTime field to use LocalDateTimeToHHmmssSerializer.class ,
Can I dynamically force to serialize this filed with another serializer?
Thanks for any help.

[JooHyukKim]

Try using another instance of ObjectMapper via '.copy()' then set customSerializer for the Pojo.
I am not 100% sure tho if custom serializer takes precedence

[chiahao]

I'm so sorry that I didn't state the question clearly.
The fist serializer is annotated inside the bean field:

@JasonSerialize(using=Serializer1.class)
LocalDateTime date;

I'd like to use Serializer2 when

ObjectMapper mapper = new ObjectMapper().registerModule(new SimpleModule().addSerializer(
    LocalDateTime.class, new Serializer2()
  ));

[cowtowncoder]

One way you could do this would be with mix-in annotations: they can override annotations on fields.

Alternatively it would be possible to use custom AnnotationIntrospector overriding findSerializer() method (I think).

[chiahao]

Does that means "Last one wins" rule doesn't simply apply to the annotation?
Is this not a common need to give a field a default serializer, and leave capacity for others to assign custom serialized?

[JooHyukKim]

No, it is not common to de/serialize a single POJO class one way or the other depending on case.

[cowtowncoder]

@chiahao I don't know what you mean by "last one wins" here. Mix-in annotations are a form of override (you can effectively replace annotations). Custom AnnotationIntrospector can similarly be used to change not to simply read annotation from field.

And no, usage pattern is not such that field annotations would be default; it is to specifically indicate THE serializer to use. Defaults are only used for types.