David Manpearl David Manpearl - 5 months ago 231
Android Question

Http Status Code in Android Volley when error.networkResponse is null

I am using Google Volley on the Android platform.
I am having a problem in which the

error
parameter in
onErrorResponse
is returning a null
networkResponse

For the RESTful API I am using, I need to determine the Http Status Code which is often arriving as 401 (SC_UNAUTHORIZED) or 500 (SC_INTERNAL_SERVER_ERROR), and I can occasionally check via:

final int httpStatusCode = error.networkResponse.statusCode;
if(networkResponse == HttpStatus.SC_UNAUTHORIZED) {
// Http status code 401: Unauthorized.
}


This throws a
NullPointerException
because
networkResponse
is null.

How can I determine the Http Status Code in the function
onErrorResponse
?

Or, how can I ensure
error.networkResponse
is non-null in
onErrorResponse
?

Answer

401 Not Supported by Volley

It turns out that it is impossible to guarantee that error.networkResponse is non-null without modifying Google Volley code because of a bug in Volley that throws the Exception NoConnectionError for Http Status Code 401 (HttpStatus.SC_UNAUTHORIZED) in BasicNetwork.java (134) prior to setting the value of networkResponse.

Work-Around

Instead of fixing the Volley code, our solution in this case was to modify the Web Service API to send Http Error Code 403 (HttpStatus.SC_FORBIDDEN) for the particular case in question.

For this Http Status Code, the value of error.networkResponse is non-null in the Volley error handler: public void onErrorResponse(VolleyError error). And, error.networkResponse.httpStatusCode correctly returns HttpStatus.SC_FORBIDDEN.

Other-Suggestions

Rperryng's suggestion of extending the Request<T> class may have provided a solution, and is a creative and excellent idea. Thank you very much for the detailed example. I found the optimal solution for our case is to use the work-around because we are fortunate enough to have control of the web services API.

I might opt for fixing the Volley code in one location within BasicNetwork.java if I did not have access to making a simple change at the server.