JSON deserializeUntyped is causing trouble and I could not understand why it would convert a Array of data to something that is neither an array nor a similar string?

To reproduce I am executing this in Execute Anonymous Dev Console:

String s = '{ "data" : [ "powerCord", "test" ] }';
system.debug('Data String :: '+s);
Map<String, Object> m = (Map<String, Object>)JSON.deserializeUntyped(s);
system.debug('Deserialized To MAP :: '+m);
system.debug('Reading Map (data) :: '+m.get('data'));
List<String> l = (List<String>)JSON.deserialize(String.valueOf(m.get('data')), List<String>.class);
system.debug('@@ '+l);

Error I get:

FATAL_ERROR System.JSONException: Unexpected character ('(' (code 40)): expected a valid value (number, String, array, object, 'true', 'false' or 'null') at input location [1,2]

Is there something wrong in my code here?

1 Answer 1


No, there's nothing wrong with your code. The parentheses are simply how System.debug() prints a List value. Note that System.debug() is not a JSON serialization; it's an idiosyncratic logging representation that may not align with any other representation of the underlying data. Your data is being deserialized correctly.

If you want a more standardized log output, you can serialize your data structure back to JSON and System.debug() that output.

  • I've updated my question with proper example code. The error received when I deserialize the m.get'data') node to it's actual data type.
    – VarunC
    Jul 13, 2021 at 15:57
  • 3
    @VarunC You've changed your question in a way that makes my answer not make sense, but it's fundamentally the same problem: String.valueOf() does not perform a JSON serialization; it yields the same representation used by System.debug(). If you want JSON, you have to explicitly use JSON.
    – David Reed
    Jul 13, 2021 at 15:59
  • Sorry. I should have Edited without removing the original question. I realize that now. I also just tried JSON.serialize() instead of String.valueOf() and it worked. Thanks for pointing that out.
    – VarunC
    Jul 13, 2021 at 16:04

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