Java NullPointerException Android截击

我的代码

public class Login extends AppCompatActivity {
DBHelper mydb;
RequestQueue requestQueue;
String em,li;
String activationurl="xxx";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);

    Button submit=(Button)findViewById(R.id.button);
    submit.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            EditText email=(EditText)findViewById(R.id.editText12) ;
            EditText license=(EditText)findViewById(R.id.editText13);
            em=email.getText().toString();
            li=license.getText().toString();

            new Asyncimg().execute();



        }
    });
}
class Asyncimg extends AsyncTask<Object, Object, JSONObject>
{




    protected JSONObject doInBackground(Object... arg0) {

        JSONObject jsonObj = new JSONObject();
        try {
            jsonObj.put("email",em);
            jsonObj.put("licensekey",li);
            Log.d("object",jsonObj.toString());
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return jsonObj;
    }



    protected void onPostExecute(JSONObject result) {

        Log.d("return",result.toString());
        JsonArrayRequest request = new JsonArrayRequest(Request.Method.POST,
                activationurl, result,
                new Response.Listener<JSONArray>() {

                    @Override
                    public void onResponse(JSONArray response) {

                        try {
                            JSONObject store = response.getJSONObject(0);
                            Log.d("responce",response.toString());
                            mydb.insertdoc(store.getInt("doctor_id"),store.getString("doctor_name"),store.getString("doctor_dob"),store.getString("doctor_gender"),store.getString("doctor_contact_no"),store.getString("doctor_email"),store.getString("doctor_license_key"));


                        } catch (JSONException e) {
                            e.printStackTrace();
                        }


                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {




                    }
                }) {

            @Override
            public String getBodyContentType() {
                return "application/json";
            }
        };
        request.setRetryPolicy(new DefaultRetryPolicy(50000,
                DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
                DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));

        requestQueue.add(request);
    }
    }
}

---

我怎样才能解决这个问题。。。另一项Volley工作完美的活动。。。我如何解决这个问题。。。我需要把这个jason发送到服务器。。。我该怎么做。。。我已尝试在清单中添加appController，但没有成功

在

setContentView

之后在

onCreate

初始化您的

requestQueue

requestQueue = Volley.newRequestQueue(context);

requestQueue = Volley.newRequestQueue(context);