How to loop through json array of json object in java

Question

I am trying to loop through the json file and find the value of particular json object. Here is my sample json:

{
  "diagram":[
             {"size":{"width":30,"height":20},"color":"blue","id":1}, 
             {"color":"red","id":2},
             {"size:{"height":30}", "id":3}
            ]
}

What i want to do is to iterate through the file and find the "id" element.

I used below code to convert the JsonFile into JsonObject and to get the value of "diagram" object

JSONArray jsonArray = new JSONArray();
JSONParser parser = new JSONParser();
Object obj = parser.parse(new FileReader("D:/test.json"));
JSONObject jsonObj = (JSONObject) obj;
for(Iterator iterator = jsonObj.keySet().iterator(); iterator.hasNext();) {
      String diagramKey = (String) iterator.next();
      jsonArray.put(jsonObj.get(diagramKey));
}

With the above code i was able to get the value of diagram object and i have put that into the jsonArray

When i am trying to print the array object i am getting output as

[[
  {"size":{"width":30,"height":20},"color":"blue","id":1}, 
  {"color":"red","id":2},
  {"size:{"height":30}", "id":3}
]]

and the jsonArray length is coming as 1.

How to loop through the above jsonArray and find the id of each individual element

Answer 1

Verify your JSON too and check below code. 

public class MyTest {

    public static void main(String[] args) throws JSONException {
        String str = "{\r\n" + 
                "   \"diagram\": [{\r\n" + 
                "           \"size\": {\r\n" + 
                "               \"width\": 30,\r\n" + 
                "               \"height\": 20\r\n" + 
                "           },\r\n" + 
                "           \"color\": \"blue\",\r\n" + 
                "           \"id\": 1\r\n" + 
                "       },\r\n" + 
                "       {\r\n" + 
                "           \"color\": \"red\",\r\n" + 
                "           \"id\": 2\r\n" + 
                "       },\r\n" + 
                "       {\r\n" + 
                "           \"size\": {\r\n" + 
                "               \"height\": 30\r\n" + 
                "           },\r\n" + 
                "           \"id\": 3\r\n" + 
                "       }\r\n" + 
                "   ]\r\n" + 
                "}";

        JSONObject jo = new JSONObject(str);
        final JSONArray geodata = jo.getJSONArray("diagram");
        int arrLength = geodata.length();
        for(int i = 0; i< arrLength;i++) {
            jo  = geodata.getJSONObject(i);
            System.out.println(jo.get("id"));
        }
    }
}

Answer 2

Your json format is wrong. You can always validate your json format using tools online

• https://jsonformatter.curiousconcept.com/
• https://jsonformatter.org/

Correct json format

{  
   "diagram":[  
      {  
         "size":{  
            "width":30,
            "height":20
         },
         "color":"blue",
         "id":1
      },
      {  
         "color":"red",
         "id":2
      },
      {  
         "size":{  
            "height":30
         },
         "id":3
      }
   ]
}