Why org.json.JSONObject getLong and getString not equal

Question

Code like this:

     JSONObject contentObject = new JSONObject(content);
     JSONObject params = contentObject.getJSONObject("response_params");
     Log.d("onTest", "channel_id:" + params.getString("channel_id"));
     Log.d("onTest", "channel_id:" + params.getLong("channel_id"));

Log print:

   08-21 12:46:21.470: DEBUG/onTest(25228): onMessage: content : {"response_params":{"appid":"1071410","channel_id":"3537275240990320342","user_id":"714893193627619861"},"request_id":1293438498}
   08-21 12:46:21.480: DEBUG/onTest(25228): channel_id:3537275240990320342
   08-21 12:46:21.480: DEBUG/onTest(25228): channel_id:3537275240990320128

Why getLong with value 3537275240990320128,but get String with value 3537275240990320342?

Answer 1

As per the documentation here,

public long getLong (String name)

Returns the value mapped by name if it exists and is a long or can be coerced to a long. Note that JSON represents numbers as doubles, so this is lossy; use strings to transfer numbers via JSON.

EDIT: To see it yourself you can do this

JSONObject json = new JSONObject();
try {
    json.put("test", "3537275240990320342");
    String str = json.getString("test");
    double dou = Double.parseDouble(str);
    long lo = (long) dou;
} catch (JSONException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

You will see that the value of lo is exactly what you are getting when you do getLong