How do I set data from volley web service to variable

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Android

webservice

Hello Friends.
I Wrote A Program that Connect to server with volley in android .
it work write but show me on screen Null .
I Use Log In Volley And See Correct Answer But In Run Program I See Null In Output.
Please Help me To find this.

What I have tried:

public String logInAdminToServer(JSONObject jsonObject) {
      JsonObjectRequest request = new JsonObjectRequest(Request.Method.POST,
              "http://192.168.43.206/project-server/Admin.php?action=LogInAdmin", jsonObject,
              new Response.Listener<JSONObject>() {
                  @Override
                  public void onResponse(JSONObject response) {
                      try {
                          firstName = response.getString("AdminFirstName");
                          lastName = response.getString("AdminLastName");
                          Log.i("Error", firstName + lastName);
                      } catch (JSONException e) {
                          e.printStackTrace();
                      }
                  }
              },
              new Response.ErrorListener() {
                  @Override
                  public void onErrorResponse(VolleyError error) {
                      Log.i("Error", error.toString());
                  }
              });
      Volley.newRequestQueue(G.context).add(request);
      return firstName + "," + lastName;
  }