sonObjectRequest actuallyaccepts JSONObject as body.
From http://arnab.ch/blog/2013/08/asynchronous-http-requests-in-android-using-volley/
final String url = "some/url";
final JSONObject jsonBody = /* ... */;
new JsonObjectRequest(url, jsonBody, new Response.Listener<JSONObject>() { ... });
Here is the offical code and javadoc (@param jsonRequest):
/**
* Creates a new request.
* @param method the HTTP method to use
* @param url URL to fetch the JSON from
* @param jsonRequest A {@link JSONObject} to post with the request. Null is allowed and
* indicates no parameters will be posted along with request.
* @param listener Listener to receive the JSON response
* @param errorListener Error listener, or null to ignore errors.
*/
public JsonObjectRequest(int method, String url, JSONObject jsonRequest,
Listener<JSONObject> listener, ErrorListener errorListener) {
super(method, url, (jsonRequest == null) ? null : jsonRequest.toString(), listener,
errorListener);
} 