爬了別人的文章用PHP顯示資料都可以顯示但在android studio上都顯示不出來

public class MainActivity extends AppCompatActivity {
    String showUri = "http://127.0.0.1/loading.php";
    com.android.volley.RequestQueue requestQueue;
    @Override
    protected void onCreate(Bundle savedInstanceState) {

        final TextView txt;
        txt =(TextView) findViewById(R.id.textView);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        requestQueue = Volley.newRequestQueue(getApplicationContext());

        JsonObjectRequest jsonObjectRequest = new JsonObjectRequest

                (Request.Method.POST,showUri, new Response.Listener<JSONObject>() {

                    @Override

                    public void onResponse(JSONObject response) {

                        System.out.println(response.toString());

                        try {

                            JSONArray data = response.getJSONArray("data");

                            //這邊要和上面json的名稱一樣

                            //下邊是把全部資料都印出來

                            for (int i = 0; i < data.length(); i++) {

                                JSONObject jasondata = data.getJSONObject(i);

                                String id = jasondata.getString("id");

                                String month_free = jasondata.getString("month_free");

                                txt.append(id + " " + month_free + " " + " \n");

//txt是textview

                            }

                            txt.append("===\n");//把資料放到textview顯示出來

                        } catch (JSONException e) {

                            e.printStackTrace();

                        }

                    }

                }, new Response.ErrorListener() {

                    @Override

                    public void onErrorResponse(VolleyError error) {

                        System.out.append(error.getMessage());

                    }

                });

        requestQueue.add(jsonObjectRequest);
    }
}