Parsing nested JSONArrays with Java

Question

I have this ugly JSON string and I need to get the totalStars which in this case is 500. I have tried quite some solutions but none seem to work.

This is the JSON:

{
  "code": 200,
  "message": "success",
  "data": [
    [
      {
        "totalPosts": 42
      }
    ],
    [
      {
        "totalStars": 500
      }
    ],
    [
      {
        "followingCount": 1
      }
    ],
    [
      {
        "followerCount": 1
      }
    ]
  ]
}

And at the moment I'm trying to get the data with this:

JSONObject jsonResult = new JSONObject(result);
JSONArray data = jsonResult.getJSONArray("data");
if(data != null) {
    String[] names = new String[data.length()];
    for(int i = 0 ; i < data.length() ; i++) {
        names[i] = data.getString(i);

    }
    System.out.println(names);
}

The JSONArray data contains the correct data, but I cant seem to get the other data out of it.

Looks like it's a JSONArray of JSONArrays, each containing a single JSONObject made up of your desired key-value pair. You probably just need to iterate one level deeper. — Mena
– Mena, Commented Aug 14, 2018 at 10:06

Avi · Accepted Answer · 2018-08-14 10:16:28Z

2

It looks like your data is an array of array of objects, not strings. You need to do something like this:

JSONObject jsonResult = new JSONObject(result);
JSONArray data = jsonResult.getJSONArray("data");
if(data != null) {
    String[] names = new String[data.length()];
    for(int i = 0 ; i < data.length() ; i++) {
        JSONArray arr = data.getJSONArray(i);
        dataObj = arr.getJSONObject(0)
        Iterator<String> keys = dataObj.keys();
        names[i] = dataObj.getString(keys.next())
    }
    System.out.println(names);
}

I probably have some syntax issues in this answer, but the main idea is that you're trying to get a string while you're dealing with array of objects (each data index is an array of objects. It just so happens to be that there's only one object in each such array)

edited Aug 14, 2018 at 10:16

answered Aug 14, 2018 at 10:07

Avi

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2 Comments

Richard Over a year ago

The String still comes out like this {"totalStars":500}

Avi Over a year ago

@kataroty - I don't remember the exact java syntax and objects, but I edited the answer. The idea is to get the array, get the iterator for the keys (which would only have one element) and get the value using the first key in the iterator.

Sumesh TG · Accepted Answer · 2018-08-14 10:08:41Z

0

public class DataObject
{
  private int code;

  public int getCode() { return this.code; }

  public void setCode(int code) { this.code = code; }

  private String message;

  public String getMessage() { return this.message; }

  public void setMessage(String message) { this.message = message; }

  private ArrayList<ArrayList<>> data;

  public ArrayList<ArrayList<>> getData() { return this.data; }

  public void setData(ArrayList<ArrayList<>> data) { this.data = data; }
}

Use this java object corresponding to your json for parsing from rest api. Use gson or jackson libraries.

answered Aug 14, 2018 at 10:08

Sumesh TG

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