JSON parsing of floating-point numbers

Recently encountered a problem in the work

Get a JSON string from a POST request from another system (as if it were written in C #)

{"Geometry": {"Rings": [[[40426489.331430912,3001752.0858958033],[40426225.692211367,3001750.0779145896],[ 40426202.957955509,3001594.0301330695],[40426290.959128119,3001559.0584689],[ 40426390.723533183,3001537.0470353812],[40426464.66273,3001645.3116807956],[ 40426489.331430912,3001752.0858958033]], "spatialreference": {"Wkid": 2364}}, "Succeed": True, "MSG": ""}

JSON parsing is then done in my system (written in Java),

Start with the JSON Lib 2.4 to parse

Get the JSON object, and then in this JSON object to calculate the area, how is not correct. Then I analyzed the parsed code.

{"Rings": [[[4.0426488e7,3001752],[4.0426224e7,3001750],[4.0426204e7,3001594],[4.0426292e7,3001559],[ 4.0426392E7,3001537],[4.0426464E7,3001645.2],[4.0426488E7,3001752]], "spatialreference": {"Wkid": 2364}}

Discover the original 40426489.331430912,3001752.0858958033

into a 4.0426488e7,3001752.

This difference is too far, the fractional part all lost

My workaround here is to avoid the JSON parsing process, split the JSON string directly, then get the part I want, and then request the service to compute the area.

The problem was solved, but I never made it clear why JSON Lib parsing is so, I thought it was C # and Java for floating-point processing caused by different.

I tried some of the JSON parsing packages that I used a lot on the web.

Gson,smartjson

The results of the analysis are

{"Rings": [[[4.042648933143091e7,3001752.0858958033],[4.042622569221137e7,3001750.0779145896],[ 4.042620295795551e7,3001594.0301330695],[4.042629095912812e7,3001559.0584689],[4.042639072353318e7, 3001537.047035381],[4.042646466273E7,3001645.3116807956],[4.042648933143091E7,3001752.0858958033]], " Spatialreference ": {" Wkid ": 2364}}

Although the use of scientific counting method, but the accuracy of no loss

Seems to be the problem with JSON lib.

JSON parsing of floating-point numbers