Drupal 8, how fix the error 'class not found' for custom class ? Its a php issue but maybe I missing a 'Drupal 8' thing ?

I have this custom module : 

&gt; mymodule (directory)
    &gt; mymodule.module
    &gt; src (directory)
        &gt; myclass.php
        &gt; myclassinterface.php


In myclass.php, I have : 

namespace Drupal\mymodule\src;

Class myclass implements myclassinterface{
    ...
}


In my mymodule.module, I have : 

use Drupal\mymodule\src\myclass;
...
function mymodule_form_alter(&amp;$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id){
    $test = new myclass();
    // or $test = new Drupal\mymodule\src\myclass(); // same error, class not found
}


And when I load a page via my browser, I get a blank page and apache log tell me the class 'Drupal\mymodule\src\myclass' not found. 

I don't understand..where is my mistake ?
Drop the "src" from your namespace and use statements. Wipe the cache after making that change.