[java] [자료구조] Remove null values from json using jackson

[Question]

I am trying to remove all the null values from my json.

{
   "key" : null
}

I have used:

ObjectMapper mapper = new ObjectMapper();
mapper.setSerializationInclusion(Include.NON_NULL);

Here "key" is a list and so when I use the above serialization option, the json gets converted to:

{
   "key" : []
}

I want the json to be:

{
}

I don't want to use

Include.NON_EMPTY

as I have other json in my project where I need to show the empty list and 0 valued keys. Is there any way to remove the null valued keys when it is a list, the same way it does for a string value?

I cannot use annotations as the class files are being generated from xml using jaxb. Class Structure:

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public class C1 {

protected List<C2> key;

public List<C2> getKey() {
    if (key == null) {
        key = new ArrayList<C2>();
    }
    return this.key;
}

}

I have been stuck for a while now. Any help is highly appreciated. Thanks in advance.

[Answer]

To suppress serializing properties with null values,

you can configure the ObjectMapper directly using this.

mapper.setSerializationInclusion(Include.NON_NULL);

[출처] https://stackoverflow.com/questions/37019059/remove-null-values-from-json-using-jackson