current community

your communities

more stack exchange communities

Stack Exchange
tour help
careers 2.0
Take the 2-minute tour ×
Stack Overflow is a question and answer site for professional and enthusiast programmers. It's 100% free, no registration required.
up vote 0 down vote favorite

I'm following this tutuorial here, and my JSON object is near enough the same, except I have this sort of format:

{"user":{
    "SomeKeys":"SomeValues",
    "SomeList":["val1","val2"]
    }
}

Here is my relevant code:

Object obj = parser.parse(new FileReader("exampleJson.json"));

JSONObject jsonObject = (JSONObject) obj;
JSONObject user = (JSONObject) jsonObject.get("user");
JSONArray list = (JSONArray) user.get("SomeList");

Then my program goes off an gets the values form the keys etc. Or it would but I get a NullPointerException from eclipse. Why is this?

It should unpackage my .json file into jsonObject, unpackage the "user" key as a JSONObject user, then unpackage the "SomeList" key as a JSONArray called list. Except when it does so it must be trying to put one of val1 or val2 into a part of the JSONArray that does not exist and just points into the abyss of null. What have I done to deserve this wrong ?

How do I fix my program?

share|improve this question
    
Isn't "SomeList":["val1","val2"] just an array instead of a JSONArray –  Hitham S. AlQadheeb Sep 19 '12 at 16:33
    
I tried your code and it works perfectly for me... Let me know if you want to post the full code of what I tried. –  aymeric Sep 19 '12 at 16:36
    
Have you tried looking with a debugger? –  Joel Sep 19 '12 at 18:04
    
@Joel No, but I will do at work tomorrow. –  Pureferret Sep 19 '12 at 18:27
    
@aymeric That would be helpful, maybe then I can spot where our code has diverged. –  Pureferret Sep 19 '12 at 18:27

2 Answers 2

up vote 0 down vote

Your code is working well for me 

public class App {

    public static void main(final String[] args) throws FileNotFoundException, IOException, ParseException {
        final Object obj = new JSONParser().parse(new FileReader("D:/a.json"));
        final JSONObject jsonObject = (JSONObject) obj;
        final JSONObject user = (JSONObject) jsonObject.get("user");
        final JSONArray list = (JSONArray) user.get("SomeList");
        System.out.println(list);
    }
}

File D:/exampleJson.json 

{"user":{
    "SomeKeys":"SomeValues",
    "SomeList":["val1","val2"]
    }
}

output is 

["val1","val2"]
share|improve this answer
    
Why have you made those objects final? –  Pureferret Sep 19 '12 at 18:53
    
coding standart –  Ilya Sep 19 '12 at 18:57
    
It turns out I had a upper/lower case error. ::facepalm:: –  Pureferret Sep 20 '12 at 8:17
    
Congratulations:) –  Ilya Sep 20 '12 at 8:48
up vote 0 down vote

Using the exact same json file:

{"user":{
    "SomeKeys":"SomeValues",
    "SomeList":["val1","val2"]
    }
}

Here is the code I use (with the imports to really make sure we have the same ones):

import java.io.FileReader;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;

public class Test {

    public static void main(String[] args) throws Exception {
        Object obj = new JSONParser().parse(new FileReader("t.json"));

        JSONObject jsonObject = (JSONObject) obj;
        JSONObject user = (JSONObject) jsonObject.get("user");
        JSONArray list = (JSONArray) user.get("SomeList");
        System.out.println(list);
    }
}

And here is the output:

["val1","val2"]

I used maven and m2e to import the library. The version used for this test was json-simple-1.1.jar.

share|improve this answer
    
It turns out I had a upper/lower case error. ::facepalm:: –  Pureferret Sep 20 '12 at 8:14

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.