使用 Android Volley 发布和获取 Json 数据

我正在尝试使用 Android Volley 发布数据并接收 Json 响应。我有下面的代码，我似乎看不到错误在哪里，因为我在网上找到的所有代码都与此类似。我附上了 android 给出的消息的截图。

public String rBody = null;//Is Initialized also tried (String)null

  public void loadSharedPreferencesData(){
    SharedPreferences sharedPre = getSharedPreferences("userinfo", Context.MODE_PRIVATE);
    final String loggedStatus = sharedPre.getString("isLogged", "0");
    final String loggedUserId = sharedPre.getString("userId", "0");

    String loginUrl         = "http://dataUrl[![enter image description here][1]][1]/startvapp-ci/appdata/getsession/";

    JsonObjectRequest  jsonObjectRequest  = new JsonObjectRequest(Request.Method.POST, loginUrl, rBody ,
            new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response){
                    //returnResponse = response.toString();
                    //Toast.makeText(getApplicationContext(), returnResponse , Toast.LENGTH_LONG).show();
                    System.out.println(response);
                    //Toast.makeText(getApplicationContext(), "Error in Response" , Toast.LENGTH_LONG).show();
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    //Save this to some global variable
                    Toast.makeText(getApplicationContext(), "Error in Response" , Toast.LENGTH_LONG).show();
                }
            }
    ){
        @Override
        protected Map<String,String> getParams(){
            Map<String,String> params = new HashMap<String, String>();
            params.put(KEY_SESS_USERID,loggedUserId);
            params.put(KEY_SESS_STATUS,loggedStatus);
            return params;
        }
    };
    MySingleton.getInstance(this.getApplicationContext()).addToRequestQueue(jsonObjectRequest);
}