CODEWITHSUNDEEP
javaarraysjson
s.dragos
s.dragos

Reputation: 682

Parse JSON file in Java: getJSONObject(int) is undefined

I`m trying to fetch some values fron a JSON file using:

JSONParser parser = new JSONParser();
Object obj = parser.parse(new FileReader("C:\\myfile.json"));
JSONArray array= new JSONArray();
array.add(obj);

If I run: System.out.println(array); , the output is 

[{"flowrate":{"mod":0,"value":110},"command":{"cancel":0,"start":0}}]

, which is my json file. My problem is how to get value from a specific field, let's say the value of "comand":"cancel".

I've tried JSONObject myitem = array.getJSONObject(1).getJSONObject("cancel"); with no success (error: getJSONObject(int) is undefined for the type JSONArray).

I mention that I'm using the json-simple toolkit.

Upvotes: 0

Views: 1222

Answers (2)

s.dragos
s.dragos

Reputation: 682

After many hours of searching, I discovered that there is big difference between { } and [ ], therefore differnent methodes to parse them:

enter image description here

In my case: 

JSONParser parser = new JSONParser();
Object obj = parser.parse(new FileReader("C:\\myfile.json"));
JSONObject jsonObject =  (JSONObject) json;
JSONObject command= (JSONObject) jsonObject.get("command");
System.out.println("command: " + command);
long cancel= (Long) command.get("cancel");
System.out.println("cancel: " + cancel);

Here you'll find the best example for nested json objects

Upvotes: 0

RBH
RBH

Reputation: 271

I also could not validate your JSON. I made an assumption that you wanted to create an array of two objects (flowrate and command) and fixed the JSON:

    String value = "[{\"flowrate\":{\"mod\":0,\"value\":110}},{\"command\":{\"cancel\":0,\"start\":0}}]";
    JSONParser parser = new JSONParser();
    Object obj = parser.parse(value);
    JSONArray array=(JSONArray)obj;
    JSONObject jo = (JSONObject) array.get(1);
    System.out.println(jo.get("command"));

which gives the following output:

{"cancel":0,"start":0}

Process finished with exit code 0

Upvotes: 1

Related Questions