NPE in JSONObject.writeValue()

[vvalchev]

A NPE can occur if we try to serialize a JSONArray that contains a 'null' value. The NPE occurs in JSONObject @ line 1509, which is:

   } else if (value.getClass().isArray()) {

At this point 'value' can be null.

This can be fixed very easy. We just need to move the if statement @ line 1523 to be the first:

    } else if (value == null || value.equals(null)) {
        writer.write("null");
   }

[vvalchev]

I was curious why an element in the JSONArray is real null, instead of the Null object defined in JSONObject, and the reason is that method of JSONArray

public JSONArray put(Object value) {
this.myArrayList.add(value);
return this;
}

Maybe the correct code is:
public JSONArray put(Object value) {
this.myArrayList.add(JSONObject.wrap(value));
return this;
}

[douglascrockford]

Thanks. Please try it now.

With respect to JSON, Java's null is ambiguous. Sometimes it means NULL, and sometimes it means something like JavaScript's undefined.