JSONArray(String json) returns "Infinite" when parsing some unquoted (invalid) JSON

Question

A curiosity:

JSONArray rfidArray1 = new JSONArray("[047c04fae63684]");

returns a JSONArray whose first value is a Double with value of Infinity, whereas:

JSONArray rfidArray1 = new JSONArray("[04b2b6f2443680]");

returns a JSONArray whose first value is a String with value of 04b2b6f2443680.

This is clearly invalid JSON which should throw a JSONException, but instead it sporadically returns broken values. It seems to be lenient with some values and return a "proper" JSONArray, but with some others it does not. Here are some more values:

Returns first value of Double with value of Infinity:

"[047c04fae63684]"
"[042579FAE63680]"
"[048C22FAE63684]"
"[049360FAE63680]"

Returns first value of String with 'proper' value:

"[04bb97d27c3680]"
"[04BB97D27C3680]"
"[04337FF2443681]"
"[04b2b6f2443680]"
"[0447E3FAE63680]"
"[\"047c04fae63684\"]"
"[\"049360FAE63680\"]"

I'm using Android 4.4.2 API level 19.

Answer 1

Your 'double' values contain the letter E, which is valid double syntax IF the parser recognized hexadecimal, which JSONArray probably does. E means in the floating point world as times 10 to the power of

numbers1[E/e]numbers2 is parsed as:

numbers1 * (10 ^ numbers2), or

numbers1 times 10 to the power of numbers2

Where numbers[1/2] represent any combination of hexadecimal digits. Sooo....

047c04fae63684 is the same as

047c04fa * (10 ^ 64684) and double does not have enough data space to hold that exponent, so it overflows and returns Infinity.

Meanwhile the JSONArray parser has no clue what to with "[04b2b6f2443680]", so im geussing it assumes that because it contains non digits, that it must be a string and it returns it as a String.

For "[\"049360FAE63680\"]" you enclosed the array value in quotes so the parser automatically sees them and says 'Hey, thats a string, lets just return that' and doesn't do anything else.

Sorry if the data is inaccurate, I have a bad head cold.