.NullPointerException while retrieving data with volley

Question

i am trying to retrieve data with volley but i keep getting this error:

This is my json file which is accessed with this link "http:/192.168.1.4/pim/get_all_bus.php" where 192.168.1.4 is my local ip address

    {
"Bus": [
    {
        "id_bus": "3",
        "name_bus": "51A",
        "terminusDepart": "Ennasr1",
        "terminus_arrivee": "TGM"
    },
    {
        "id_bus": "4",
        "name_bus": "51A",
        "terminusDepart": "Ennasr2",
        "terminus_arrivee": "tunis"
    }
],
"success": 1
}

the error that i am getting is this

   04-09 14:40:00.589 5256-5256/info.androidhive.volleyexamples E/AndroidRuntime: FATAL EXCEPTION: main
                                                                           Process: info.androidhive.volleyexamples, PID: 5256
                                                                           java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.hashCode()' on a null object reference
                                                                               at com.android.volley.Request.<init>(Request.java:136)
                                                                               at com.android.volley.toolbox.JsonRequest.<init>(JsonRequest.java:58)
                                                                               at com.android.volley.toolbox.JsonArrayRequest.<init>(JsonArrayRequest.java:42)
                                                                               at info.androidhive.volleyexamples.JsonRequestActivity.makeJsonArryReq(JsonRequestActivity.java:111)
                                                                               at info.androidhive.volleyexamples.JsonRequestActivity.onClick(JsonRequestActivity.java:146)
                                                                               at android.view.View.performClick(View.java:5697)
                                                                               at android.widget.TextView.performClick(TextView.java:10826)
                                                                               at android.view.View$PerformClick.run(View.java:22526)
                                                                               at android.os.Handler.handleCallback(Handler.java:739)
                                                                               at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                               at android.os.Looper.loop(Looper.java:158)
                                                                               at android.app.ActivityThread.main(ActivityThread.java:7224)
                                                                               at java.lang.reflect.Method.invoke(Native Method)
                                                                               at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
                                                                               at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)

the function that i am using is this one :

    private void makeJsonArryReq() {
    showProgressDialog();
    JsonArrayRequest req = new JsonArrayRequest("http:/192.168.1.4/pim/get_all_bus.php",
            new Response.Listener<JSONArray>() {
                @Override
                public void onResponse(JSONArray response) {
                    Log.d(TAG, response.toString());

                        msgResponse.setText(response.toString());


                    //msgResponse.setText(response.toString());
                    hideProgressDialog();
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    VolleyLog.d(TAG, "Error: " + error.getMessage());
                    hideProgressDialog();
                }
            });

    // Adding request to request queue
    AppController.getInstance().addToRequestQueue(req,
            tag_json_arry);

    // Cancelling request
    // ApplicationController.getInstance().getRequestQueue().cancelAll(tag_json_arry);
}

Answer 1

Here you need to call JsonObjectRequest first. Your given link, returns a json object. After getting the json object, you need to parse the data.

Answer 2

Quick tip. In the JSON format curly brackets "{}" defines an object and third brackets "[]" defines an array.

Now look at the response from your PHP script. It starts with a curly bracket. That means your response is a JSON object. Therefore, you need to call a JSONObjectRequest from volley and not a JSONArrayRequest.