java - Unable to put null values in JSON object

Question

I am trying to pass parameter to api using JSON.

class Sample
{ ...
   String token;
...

void method()
{ ...
    JSONObject params = new JSONObject();
    params.put(KEY_TOKEN,token);
    params.put(KEY_DATE,date);

    Log.e("params ",params+"");


      ...  }    

I get the value of params as {"date":"2017-06-19"} but token is seen nowhere. I have not initialized token and its value is null as its an instance variable. So is it something that uninitialized value are not included?

Answer 1

Right there in the documentation, in the first paragraph:

Values may not be null, NaNs, infinities, or of any type not listed here.

So yes, it is "...something that null values are not included..." (edit: that was a quote from your original question; your updated question changes it to "uninitialized values" but the default value of an object reference is null, so...)

It's a "feature" of that class, though; JSON itself understands null just fine. Further down in the documentation it says you use a "sentinal value," NULL, to represent null. Which seems...odd. There's a note about it:

Warning: this class represents null in two incompatible ways: the standard Java null reference, and the sentinel value NULL. In particular, calling put(name, null) removes the named entry from the object but put(name, JSONObject.NULL) stores an entry whose value is JSONObject.NULL.

So:

params.put(KEY_TOKEN, token == null ? JSONObject.NULL : token);