Java - update object in array of objects

Question

I would like to update an object in array of objects.

For example, in this object:

Form form = 
{
  "id": "c84d93a3-c0fd-4f53-8b72-76e8eXXXXXX",
  "book": {
    "register": [
      {
        "header": "Header 1",
        "questions": [
          {
            "id": "87b8c60c-9c9e-41d1-a52a-588400XXXXXX",
            "label": "Question 1-A",
            "answers": [
              {
                "id": 1,
                "defaultValue": "Hello world",
                "layout": "SIMPLE",
                "textAllowedValue": "TEXT",
                "textTransformation": "UPPERCASE",
                "maxLength": 120,
                "userValue": "HELLO WORLD"
              }
            ]
          }
        ]
      },
      {
        "header": "Header 2",
        "questions": [
          {
            "id": "87b8c60c-9c9e-41d1-a52a-588400XXXXXX",
            "label": "Question 2-A",
            "answers": [
              {
                "id": 1,
                "defaultValue": "Answer 1",
                "layout": "SIMPLE",
                "textAllowedValue": "TEXT",
                "textTransformation": "UPPERCASE",
                "maxLength": 120,
                "userValue": "ANSWER 1"
              },
              {
                "id": 2,
                "defaultValue": "Answer 2",
                "layout": "SIMPLE",
                "textAllowedValue": "TEXT",
                "textTransformation": "UPPERCASE",
                "maxLength": 120,
                "userValue": "ANSWER 1"
              },
              {
                "id": 3,
                "defaultValue": "Answer 3",
                "layout": "SIMPLE",
                "textAllowedValue": "TEXT",
                "textTransformation": "UPPERCASE",
                "maxLength": 120,
                "userValue": "ANSWER 3"
              }
            ]
          },
          {
            "id": "87b8c60c-9c9e-41d1-a52a-588400XXXXXX",
            "label": "Question 2-B",
            "answers": [
              {
                "id": 1,
                "defaultValue": "Answer 1",
                "layout": "SIMPLE",
                "textAllowedValue": "TEXT",
                "textTransformation": "UPPERCASE",
                "maxLength": 120,
                "userValue": "ANSWER 1"
              },
              {
                "id": 2,
                "defaultValue": "Answer 2",
                "layout": "SIMPLE",
                "textAllowedValue": "TEXT",
                "textTransformation": "UPPERCASE",
                "maxLength": 120,
                "userValue": "ANSWER 1"
              },
              {
                "id": 3,
                "defaultValue": "Answer 3",
                "layout": "SIMPLE",
                "textAllowedValue": "TEXT",
                "textTransformation": "UPPERCASE",
                "maxLength": 120,
                "userValue": "ANSWER 3"
              }
            ]
          }
        ]
      }
    ]
  }
}

I want to update this 'Answer' object:

{
                "id": 3,
                "defaultValue": "Answer 3",
                "layout": "SIMPLE",
                "textAllowedValue": "TEXT",
                "textTransformation": "UPPERCASE",
                "maxLength": 120,
                "userValue": "ANSWER 3"
              }

by this object:

newObject = {
                "id": 3,
                "defaultValue": "Answer 4",
                "layout": "MULTIPLE",
                "textAllowedValue": "TEXT",
                "textTransformation": "UPPERCASE",
                "maxLength": 150,
                "userValue": "ANSWER 4"
              }

The ideal would be to have a library (such as ObjectMapper()) that allows you to do the following line:

formUpdated = new ObjectMapper().updateWithObject(form, newObject) 

Is it possible to map by several keys so that the mapper identifies the object to update and does the update at the same time?

Answer 1

You need to first parse the JSON into a Form POJO, then you can do something like

Answer[] answers = 
  form.getBook().getRegisters()[1].getQuestions()[0].getAnswers();
answers[2] = newAnswer;

// convert back
String out = mapper.writeValueAsString(form);

If you want to do individual fields, then answers[2].setFoo(newBar)