无法在回收器视图中使用volley从mysql检索数据

Question

嘿，我在volley sql中使用数组获取Json数据，但发现错误，数据未在recycler view中加载。我正在获取具有相同 id 的所有行。但数据未加载。这是我的代码，你能告诉我错误在哪里吗？

private void LoadAllJobs() {
    StringRequest stringRequest = new StringRequest(Request.Method.POST, Urls.all_jobs,
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    try {
                        JSONArray jsonArray = new JSONArray(response);
                        for (int i = 0; i < jsonArray.length(); i++) {
                            JSONObject object = jsonArray.getJSONObject(i);
                            String jobname = object.getString("jobname");
                            String jobdetails = object.getString("jobdetails");
                            String startdate = object.getString("startdate");
                            String enddate = object.getString("enddate");
                            String posts = object.getString("posts");
                            String govtfees = object.getString("govtfees");
                            String appfees = object.getString("appfees");
                            String documents = object.getString("documents");
                            String declartion = object.getString("declartion");


                            AllJobsModel alljobsName = new AllJobsModel(jobname, jobdetails, posts, startdate, enddate, govtfees, appfees, documents, declartion);
                            alljobsName.setJobName(jobname);
                            alljobsName.setJobDetails(jobdetails);
                            allJobs.add(alljobsName);


                        }
                    } catch (JSONException e) {
                        e.printStackTrace();
                        AndroidUtil.showToast(getApplicationContext(),e.toString());
                    }
                }
            }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            error.printStackTrace();
        }
    }){
        @Nullable
        @Override
        protected Map<String, String> getParams() throws AuthFailureError {
            Map<String, String> params = new HashMap<>();
            params.put("id","1");
            return params;
        }

    };
        RequestQueue queue=  Volley.newRequestQueue(MainActivity.this);
        queue.add(stringRequest);


    }

<?php

    require_once "conn.php";
    require_once "validate.php";
    $id = $_POST['id'];
    $sql = "SELECT * from all_jobs WHERE id ='$id'";
    $result=mysqli_query($conn, $sql);
    $all_jobs= array();
    while($row=mysqli_fetch_array($result)){
        
        
        $index['jobname']=$row['jobname'];
        $index['posts']=$row['posts'];
        $index['startdate']=$row['startdate'];
        $index['enddate']=$row['enddate'];
        $index['govtfees']=$row['govtfees'];
        $index['appfees']=$row['appfees'];
        $index['documents']=$row['documents'];
        $index['declartion']=$row['declartion'];
        $index['jobdetails']=$row['jobdetails'];
        

        array_push($all_jobs, $index);
    }
    echo json_encode($all_jobs)
?>    

请帮我修复它，数据未加载，并且在应用程序中显示 json 错误无法将字符串转换为 json 数组 // 类似这样。帮助我，我非常接近完成我的应用程序

Answer 1

该错误表明您从 PHP 脚本收到的响应存在问题。当响应不是有效的 JSON 数组时，通常会发生此错误。在 PHP 代码中，您正在回显 JSON 编码的数据，但确保响应是有效的 JSON 非常重要。

这是 PHP 修正：

<?php
require_once "conn.php";
require_once "validate.php";

$id = $_POST['id'];
$sql = "SELECT * FROM all_jobs WHERE id = '$id'";
$result = mysqli_query($conn, $sql);
$all_jobs = array();

while ($row = mysqli_fetch_array($result)) {
    $index['jobname'] = $row['jobname'];
    $index['posts'] = $row['posts'];
    $index['startdate'] = $row['startdate'];
    $index['enddate'] = $row['enddate'];
    $index['govtfees'] = $row['govtfees'];
    $index['appfees'] = $row['appfees'];
    $index['documents'] = $row['documents'];
    $index['declartion'] = $row['declartion'];
    $index['jobdetails'] = $row['jobdetails'];

    array_push($all_jobs, $index);
}

header('Content-Type: application/json');
echo json_encode($all_jobs);
?>

1. 再次在浏览器中测试您的 PHP 脚本，以确保它返回有效的 JSON 数据。
2. 在您的 Android 代码中，确保 URL Urls.all_jobs 指向 PHP 脚本的正确位置，并且在 getParams 方法中正确发送 id 参数。