使用数组从 JSON 创建 POJO model

Question

I am trying to create a java model for a JSON structure that looks like this:

"notification": {
      "field": "string",           
      "object": [
      {
        "field2": "string",
        "object2": [
          {
            "field3": "string",
            "object3": {
              "code": "string",
              "proprietary": "string"
            }
          }
        ]
      }
    ]
 }

So far my model looks like this:

public class Notification {

      private String field = "sample value";
      public List<object> sampleObject= new ArrayList<object>();

        public String getField() {
            return field;
        }

        public void setField(String notifyingParticipantfinancialInstitutionBIC) {
            this.field = field;
        }

        public List<object> getObject() {
            return object;
        }

        public void setObject(List<object> sampleObject) {
            this.sampleObject = sampleObject;
        }
    }
    
    public class object{

        public String field2 = "string";
        public List<object2> sampleObject2 = null;

        public String getField2() {
            return field2;
        }

        public void setField2(String field2) {
            this.field2 = field2;
        }

        public List<object2> getObject2() {
            return object2;
        }

        public void setObject2(List<object2> sampleObject2) {
            this.object2 = object2;
        }
    }

I have populated some of the existing fields just to make sure I can print back a json from this POJO model. When I print it using:

ObjectMapper mapper = new ObjectMapper();
            Notification test = new Notification();
            String jsonInString = mapper.writeValueAsString(test);

i get this JSON object:

"notification": {
        "field": "string",
        "object": []
    }

What am I doing wrong with my 1st object class? I'm not sure why the List is not populating all the other nested variables and objects within it, but returning an empty array.

////

Just fixed it thanks to pleft and Nagaraju Chitimilla's correction. I had to add the new objects to my main object.

Answer 1

Did you created and added object and object2?

eg

 Notification test = new Notification();
object obj =new object();
List list = new ArrayList<>();
list.add(obj);
test.setObject(list);

Answer 2

You need to add some objects in your list!

eg

Notification test = new Notification();
test.getObject().add(new object()); //Add a new object in your object list