How to set null value in org.json.JSONObject in java?

Question

How to set null value in org.json.JSONObject in java? I can of course read if the value is null using isNull - but it seems that when I put null, it just ignores me:

JSONObject o = new JSONObject(); o.put("key",null); o.isNull("key"); // returns true, buuuut... o.has("key"); // returns false o.isNull("somethingIHaventSetAtAll"); // also returns true, unfortunately 

Answer 1

Try setting JSONObject.NULL instead of null :

A sentinel value used to explicitly identify a name without a value. Unlike null, names with this value:

• displayed in names () array
• displayed in () iterator keys
• return true for has (String)
• don't throw get (String)
• included in the JSON encoded string.

This value violates the general equals (Object) contract, returning true compared to null. Its toString () method returns "null".