php - java.lang.String类型的值成功无法转换为JSONObject

Question

我在 Activity A 中有一个listView。当检测到长按时，会检查iD是否为最大值。如果是，列表将被删除并刷新列表。否则会显示“列表无法删除”。

 listViewUpdate.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            public boolean onItemLongClick(final AdapterView<?> p, View v, final int po, long id) {

                iD = details1.get(po).getID();
                AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
                builder.setTitle("Delete");
                builder.setMessage("Are you sure you want to delete?");
                builder.setIcon(android.R.drawable.ic_dialog_alert);
                builder.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int ii) {
                        checkMaxID(po,ID,iD);
                        RetrieveTotalHours(ID);

                    }
                });

                builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener()

                        {
                            public void onClick(DialogInterface dialog, int ii) {
                                dialog.dismiss();
                            }
                        }

                );
                builder.show();
                return true;
            }
        });

        return edit_details;
    }

    public void checkMaxID(final int po,final int foreignKey,final String iD)
    {
        class check extends AsyncTask<Void,Void,String>{
            // ProgressDialog loading;
            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                // loading = ProgressDialog.show(Edit_Staff.this,"Updating...","Wait...",false,false);
            }

            @Override
            protected void onPostExecute(String s) {
                super.onPostExecute(s);
                Toast.makeText(getActivity(), s, Toast.LENGTH_LONG).show();
                try{
                    JSONObject json = new JSONObject(s);
                    if(json.getBoolean("success")){
                        objadapter.removeItem(po);
                        objadapter.notifyDataSetChanged();
                        Toast.makeText(getActivity(), json.getString("message"), Toast.LENGTH_LONG).show();
                        Log.e("List", "deleted");
                    }else{
                        Toast.makeText(getActivity(), json.getString("message"), Toast.LENGTH_LONG).show();
                        Log.e("List", " Not deleted");
                    }
                }catch(JSONException ex){
                    ex.printStackTrace();
                    Log.e("LISDSSS","ex="+ex.toString());

                }
            }


            @Override
            protected String doInBackground(Void... params) {
                HashMap<String,String> hashMap = new HashMap<>();
                hashMap.put(Configs.KEY_ID, iD);
                hashMap.put(Configs.KEY_TWD, String.valueOf(foreignKey));
                RequestHandler rh = new RequestHandler();
                String s = rh.sendPostRequest(Configs.URL_CHECK_ID, hashMap);
                return s;
            }
        }

      check ue = new check();
        ue.execute();
        }

php

<?php
$json = array();
if(isset($_POST['id'], $_POST['twd'])){
    /*Importing our db connection script*/
    require_once('dbConnect.php');
    /* check connection */
    if (mysqli_connect_errno()) {
        printf("Connect failed: %s\n", mysqli_connect_error());
        exit();
    }
    $id = mysqli_real_escape_string($con, $_POST['id']);
    $twd = mysqli_real_escape_string($con, $_POST['twd']);

    $sql ="SELECT MAX(id) as MaxId FROM work_details WHERE twd = '$twd'";

    if ($result = mysqli_query($con, $sql)) {
        /* fetch associative array */
        if ($row = mysqli_fetch_row($result)) {
            if($row[0] === $id){
                $sql ="DELETE FROM work_details WHERE id='$id';";
                if ($result = mysqli_query($con, $sql)) {
                    echo 'success';
                    $json['success'] = true;
                    $json['message'] = 'delete is successful';
                }else{
                    $json['success'] = false;
                    $json['message'] = 'list cannot be deleted';
                }
            }else
                echo 'list cannot be deleted';
                $json['success'] = false;
                $json['message'] = '($row[0] !== $id)';         
            }
        } else{
            $json['success'] = false;
            $json['message'] = 'select is unsuccessful';            
        }
    /* close connection */
    mysqli_close($con);
    }

?>

在MySQL中删除了具有最大iD的列表，但问题是列表不刷新。

LogCat

 E/LISDSSS﹕ ex=org.json.JSONException: Value success of type java.lang.String cannot be converted to JSONObject

这是我从 catch block 中的 ex.printStackTrace(); 得到的。

任何帮助将不胜感激。

Answer 1

由于以下回显，php 方法返回字符串“success”:

$sql ="DELETE FROM work_details WHERE id='$id';";
if ($result = mysqli_query($con, $sql)) {
   echo 'success';
   $json['success'] = true;
   $json['message'] = 'delete is successful'; 

方法 onPostExecute() 在这里失败

JSONObject json = new JSONObject(s); 

因为结果String 's'是echo返回的String“success”，而不是$json对象。

尝试消除这些 echo 。