致命错误-调用未定义的方法“customersss::throwerror()”

我创建了一个类并尝试调用一个方法,但是在 错误日志 ,我得到回应 "Uncaught Error: Call to undefined method Customersss::throwError()" ,请问我做错了什么,因为我知道我创造了 throwError() ,我似乎无法访问该类。

首先是要打电话给 对象

$this->throwError(INVALID_DATA_TTT, "Invalid shipping fee"); //WHERE I SUSPECT ERROR IS BEING GENERATED

完全错误

   PHP Fatal error:  Uncaught Error: Call to undefined method
   Customersss::throwError() in
   /home/osconliz/public_html/Osconlizapicall/customers.php:276 Stack
   trace:
   #0 /home/osconliz/public_html/Osconlizapicall/api.php(177): Customersss->insertNewDelivery()
   #1 [internal function]: Api->create_insert_new_delivery()
   #2 /home/osconliz/public_html/Osconlizapicall/rest.php(42): ReflectionMethod->invoke(Object(Api))
   #3 /home/osconliz/public_html/Osconlizapicall/index.php(4): Rest->processApi()
   #4 {main}   thrown in /home/osconliz/public_html/Osconlizapicall/customers.php on line 276

客户.php

require_once('constants.php');
require_once('rest.php');   
class Customersss {     
private $id;
private $shipping_fee;
private $pickup_fee; 

function setId($id){ $this->id = $id; }
function getId() { return $this->id; }

function setShipping_fee($shipping_fee){ $this->shipping_fee = $shipping_fee; }
function getShipping_fee() { return $this->shipping_fee; }

function setPickup_fee($pickup_fee){ $this->pickup_fee = $pickup_fee; }
function getPickup_fee() { return $this->pickup_fee; }

public function __construct(){
$db = new DbConnect();
$this->dbConn = $db->connect();
}

public function insertNewDelivery(){
if ($this->shipping_fee == ""){
$this->throwError(EMPTY_PARAMETER, "Empty shipping fee");
exit();
}   

if ($this->shipping_fee == ""){
$this->throwError(INVALID_DATA_TTT, "Invalid shipping fee");
exit();
}   
}


}

REST PHP

 require_once('constants.php');
    class Rest {
    protected $request;
    protected $serviceName;
    protected $param;

      public function processApi(){
      $api = new API;
      $rMethod = new reflectionMethod('API', $this->serviceName);
      if(!method_exists($api, $this->serviceName)){
      $this->throwError(API_DOST_NOT_EXIST, "API does not exist");
       }
        $rMethod->invoke($api);
    }

    public function throwError($code, $message){
         header("content-type: application/json");
         $errorMsg = json_encode(['error' => ['status'=>$code, 'message'=>$message]]);
         echo $errorMsg; exit;       
    }
    }

常量.php

 define('INVALID_DATA_TTT',          350);
     define('EMPTY_PARAMETER',           404);
     define('API_DOST_NOT_EXIST',        400);
     define('ACCESS_TOKEN_ERRORS',       500);

API.PHP

require_once "customers.php";
require_once "constants.php";

class Api extends Rest {
public $dbConn;  

public function __construct(){
parent::__construct();  
$db = new DbConnect;
$this->dbConn = $db->connect();

}
  public function create_insert_new_delivery(){
  $shipping_fee= $this->validateParameter('item_category', $this->param['shipping_fee'], STRING, true);


  try {
 $cust = new Customersss;
 }  catch (Exception $e){
 $this->throwError(ACCESS_TOKEN_ERRORS, $e->getMessage());

}
}