Parsing nested json array in java

Question

I have json file in below format.

{
    "data":[ 
        {
          "prjId": 1,
          "name" : "Forj1",
          "issue": [
                    {
                      "id": 00001,
                      "status" : "Closed"
                    },
                    {
                      "id": 00002,
                      "status" : "Open"
                    }
                ]
          },  
          {
          "prjId": 2,
          "name" : "Forj2",
          "issue": [
                    {
                      "id": 00003,
                      "status" : "Closed"
                    },
                    {
                      "id": 00004,
                      "status" : "Open"
                    }
                ]
          }],
    "issueCounter": 7,
    "success": true
}

Here "data" is array of projects, and within project attribute there is array of "issue".

So far if I remove "issue" array, I am able to traverse the json to one level down in "data" attribute, If this json has "issue" array I get an error saying missing comma.

javax.json.stream.JsonParsingException: Invalid token=NUMBER at (line no=15, column no=14, offset=242) Expected tokens are: [COMMA]

Below is the code that I have right now. I have two problems with this, one is the error while reading if I place the "issue" attribute, and secondly a way to read the "issue" array and traverse all attributes within.

InputStream fis = new FileInputStream(pathToFile+"data3.json");
JsonReader jsonReader = Json.createReader(fis);

//the error is thrown on below line while reading the above json. 

JsonObject jsonObject = jsonReader.readObject();

jsonReader.close();
fis.close();

System.out.println(jsonObject.getInt("issueCounter"));

//reading arrays from json
JsonArray jsonArrayData = jsonObject.getJsonArray("data");
Project [] prj = new Project[jsonArrayData.size()];
int index = 0;
for(JsonValue value : jsonArrayData){

    JSONObject jsonObj = new JSONObject(value.toString());
    System.out.println(jsonObj.getString("name"));
    System.out.println(jsonObj.getInt("prjId"));

    //this is also the place where I am stuck, I know I need to construct an array out of it by obtaining issue attribute. Below is very very wrong.
    /*
    JsonArray jsonArrayIssue = jsonObj.getJsonArray("issue");
    for(JsonValue issue : jsonArrayIssue){

        JSONObject jsonIssueObj = new JSONObject(issue.toString());
        System.out.println(jsonIssueObj.getString("status"));
        System.out.println(jsonIssueObj.getInt("id"));
    }
    */
}

Any help or pointers is deeply appreciated. I can tweak the json if its required ultimately I need to maintain an array of issues.

One alternative would be to just use gson and let use reflection for you — 0x6C38
– 0x6C38, Commented Dec 7, 2016 at 11:55

isah · Accepted Answer · 2016-12-07 12:32:00Z

3

The problem as others said is the JSON. "id": 00001 <-- this is a number, numbers cannot start with a leading zero as per JSON stadard. If you control the JSON you should tweak it.

Alternatively ff you don't, you can use a less strict parser like org.json.simple https://mvnrepository.com/artifact/com.googlecode.json-simple/json-simple The code will be the same as yours, just adjusted to org.json.simple

try {   ...
        JSONObject rootJSON = (JSONObject) new JSONParser().parse(jsonString);
        JSONArray dataList = (JSONArray) rootJSON.get("data");
        for(Object projectObj: dataList.toArray()){
            JSONObject project = (JSONObject)projectObj;
            JSONArray issueList = (JSONArray) project.get("issue");
            for(Object issueObj: issueList.toArray()){
                JSONObject issue = (JSONObject) issueObj;
                //do something with the issue
            }
        }
    } catch (ParseException e) {
        //do smth
        e.printStackTrace();
    }

answered Dec 7, 2016 at 12:32

isah

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1 Comment

vick_4444 Over a year ago

Thanks a lot for the help. Changing the number to string as mentioned by below post and then parsing it the way shown by you worked for me.

Javasamurai · Accepted Answer · 2016-12-07 12:04:12Z

1

Your json data is invalid.You can check here. http://jsonlint.com
...issue": [{ "id": 00001, "status": ----------------------^ Your id must be string number,string,boolean.Send 1,2,3,.... as return values and check if it works.

answered Dec 7, 2016 at 12:04

Javasamurai

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1 Comment

vick_4444 Over a year ago

Thanks for the help, changing it to String helped along with the parsing process given by "isah".

David · Accepted Answer · 2016-12-07 12:07:56Z

1

Your code looks okay the problem is the JSON formatting. Specifically the following lines:

"id": 00001, "id": 00002, "id": 00003, "id": 00004,

Basically if you want it in that format you will need to set them as strings by wrapping the values in quotations i.e. "id": "00001" or you can use a valid number i.e. "id": 1

answered Dec 7, 2016 at 12:07

David

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1 Comment

vick_4444 Over a year ago

Thanks for the help, changing it to String helped along with the parsing process given by "isah".

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