试图从我的php api中得到一个值，在android上，使用截击。。。我的api运行良好，返回了我想要的值，但在android上，我似乎可以将值保存在一个变量上。
这是我的php脚本

<?php

if($_SERVER['REQUEST_METHOD']=='POST'){

$titu = $_POST['titulo'];
$id_use = $_POST['id_user'];
$difi = $_POST['dificuldade'];

$user = "root";
$pass = "";
$host= "localhost";
$dbname="check";

$con = mysqli_connect($host,$user,$pass,$dbname);
$sql="insert into trilhos(titulo,id_user,dificuldade) 
values('".$titu."','".$id_use."','".$difi."');";

$r = mysqli_query($con,$sql);

$id_trilho =mysqli_insert_id($con);

$result = array();
echo json_encode(array("result"=>$id_trilho));

mysqli_close($con);
}

在我的android studio上，我试图得到这样的值，我发送3个值插入到数据库中，然后我想把我插入的行的id返回给android。我看了很多关于stackoverflow的答案，但我似乎不能理解和解决我的问题。

public void insert(String titulo, String id_trilho, String dif) {
    url = "http://192.168.1.68/loginsignup/insertTrilho.php?titulo=" + titulo +"&id_user="+ id_trilho+ "&dificuldade=" + dif + "";
    Log.i("Http", "" + url);
    RequestQueue requestQueue = Volley.newRequestQueue(InserirTrilho.this);
    StringRequest stringRequest = new StringRequest(Request.Method.POST, url, new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {
            try {
                JSONObject jsonObject = new JSONObject(response);
                JSONArray jsonArray = jsonObject.getJSONArray("result");
                JSONObject jsonObject1 = jsonArray.getJSONObject(0);
                String id = jsonObject1.getString("id_trilho");
                Toast.makeText(InserirTrilho.this, id, Toast.LENGTH_SHORT).show();

                SharedPreferences shared_id = getSharedPreferences("Mytrilho", Context.MODE_PRIVATE);
                SharedPreferences.Editor editor = shared_id.edit();
                editor.putString("id", id);

                editor.commit();
                Intent intent = new Intent(InserirTrilho.this, MapsActivity.class);
                startActivity(intent);

            } catch (JSONException e) {
                e.printStackTrace();
                Toast.makeText(InserirTrilho.this, "Dados Errados", Toast.LENGTH_SHORT).show();
            }
        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Log.i("HttpError","erro"+error);
        }

    });
    requestQueue.add(stringRequest);
}

不断抛出异常，有人能帮我吗，提前谢谢