How Can I Prevent Jackson from Serializing Null Fields in Java?

Suppressing Null Field Serialization with Jackson

Jackson is a popular Java data binding library that handles serialization and deserialization between Java objects and JSON. By default, Jackson will serialize all non-null fields of an object. However, there may be scenarios where you want to ignore certain fields during serialization if their values are null.

Using @JsonInclude Annotation

Jackson 2.0 and later introduces the @JsonInclude annotation, which allows you to specify when a field should be included or excluded during serialization. To ignore a field if its value is null, use the Include.NON_NULL value:

@JsonInclude(Include.NON_NULL)
public class SomeClass {
  private String someValue;
}

With this annotation applied to the field, Jackson will skip over the someValue field during serialization if it is null.

Modifying ObjectMapper Configuration

Alternatively, you can configure the ObjectMapper directly to suppress the serialization of null values. To do so, use the setSerializationInclusion method with the Include.NON_NULL value:

mapper.setSerializationInclusion(Include.NON_NULL);

This will instruct Jackson to ignore all null fields during serialization for all objects mapped by the mapper.

Using @JsonInclude in Getters

Another option is to use the @JsonInclude annotation in the getter method for a field. This allows you to control the inclusion or exclusion of a field based on the returned value. For example:

public class SomeClass {
  private String someValue;
  
  @JsonInclude(JsonInclude.Include.NON_NULL)
  public String getSomeValue() {
    return someValue;
  }
}

In this case, the someValue field will only be included during serialization if the getter method returns a non-null value.

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