Loop through nested JSON array

Question

I have a JSON response that looks like this:

{
    "1":{
        "id":"1",
        "user_id":"1",
        "children":[
            {
                "id":"2",
                "user_id":"2",
                "children":[
                    {
                        "id":"3",
                        "user_id":"3",
                        "children":[
                            {
                                "id":"4",
                                "user_id":"2",
                                "children":[

                                ]
                            }
                        ]
                    },
                    {
                        "id":"5",
                        "user_id":"1",
                        "children":[

                        ]
                    }
                ]
            },
            {
                "id":"6",
                "user_id":"2",
                "children":[

                ]
            }
        ]
    },
    "7":{
        "id":"7",
        "user_id":"2",
        ...
    }
}

As you can see, I have nested arrays (children). I need to loop through this JSON response, going through each nested array until it runs into an empty children array, and then takes a step back to continue to the rest of the items.

I made a model class for the response, so my current code looks like this:

for (Post post : postResponse.getData()) {
    //
}

Which obviously only iterates through the top-level items (id 1 and 7 in my case).

How can I do this?

Any reason not to just use Jackson and have a List<Person> children on a Person class? — chrylis -cautiouslyoptimistic-
– chrylis -cautiouslyoptimistic-, Commented Dec 31, 2015 at 7:06
please post bit more code you tried.will helpful to extend help — Bharat DEVre
– Bharat DEVre, Commented Dec 31, 2015 at 8:02

ramin bakhshpour · Accepted Answer · 2015-12-31 07:12:14Z

1

you need a recursive function.

function iterateTree(object) {
  if (!object) { //recursion stop criteria || you need to implement what your stop criteria is
     return;
  }
  //doSomthingWithObject();
  iterateTree(object.children);
}

I'm sure you figure it out how to use it in java.

answered Dec 31, 2015 at 7:12

ramin bakhshpour

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Comments

lewis machilika · Accepted Answer · 2021-09-07 06:48:43Z

0

You may try

        public void printJsonObject(JSONObject jsonObj) {
            for (String keyStr : jsonObj.keySet()) {
                Object keyvalue = jsonObj.get(keyStr);

                //Print key and value
                System.out.println("key: "+ keyStr + " value: " + keyvalue);

                //for nested objects iteration if required
                if (keyvalue instanceof JSONObject)
                    printJsonObject((JSONObject)keyvalue);
            }

        }

answered Sep 7, 2021 at 6:48

lewis machilika

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