I need to modify JSON object value at run time.

[GoogleCodeExporter]

{
    "header": {
        "requestId": null
    },
    "data": [
        {
            "userId": 848478948947,
            "userName": "dsjflkjdklsfj38473",
            "gender": "M",
            "location": {
                "isFromUS": true,
                "zip": "454543",
                "city": "fgfdg",
                "state": "fgfdgfdg",
                "country": "USA"
            },
            "provider": "gfdgfdgds",
            "fullName": null
        }
    ]
}

From the above json String i need to modify the userName, zip value at run time 
and finally make this string as JSONObject and write in the .json file.

Can any one provide me the solution for this with Json - simple
Thanks in advance

Original issue reported on code.google.com by ssireku...@gmail.com on 26 Feb 2015 at 12:57