Convert string "null" to null value(JSONNull)

[Alexey]

Hello

I want to read/write real string value "null"(as name anything), but string "null"(any of different 16 combinations, if use any character case: "NULL", "nUll", "NulL", ...) converts to null (JSONNull object).

Example code:
public class Test_JSON extends TestCase {
    public void test() {
        final Map map = new HashMap();
        map.put("key", "null");
        JSONObject jsonObject = new JSONObject(map);
        System.out.println("JSON Object from Map:");
        System.out.println(jsonObject.toString(4));
        String json = "{key1:\"null\"}";
        System.out.println();
        System.out.println("JSON String(source):");
        System.out.println(json);
        jsonObject = new JSONObject(json);
        System.out.println();
        System.out.println("JSON Object:");
        System.out.println(jsonObject.toString(4));
        System.out.println();
        System.out.println("Real object:");
        System.out.println(jsonObject.get("key1").getClass());
    }
}

Output:

JSON Object from Map:
{"key": null}

JSON String(source):
{key1:"null"}

JSON Object:
{"key1": null}

Real object:
class net.sf.json.JSONNull

Is this correct behaviour?

Thanks

[aalmiray]

Alexey,
The string [null] or any permutation with lower/upper case will case the value to be converted to a JSONNull as you describe.
Have you tried the following string "'null'" or even "\"null\""?