I am trying to throw back values that are calculated in submitForm() to buildForm().

How do I add more state values into it?

    /**      * @file      * Contains DrupalresumeFormResumeForm.      */     namespace DrupalresumeForm;      use DrupalCoreFormFormBase;     use DrupalCoreFormFormStateInterface;      class ResumeForm extends FormBase {       /**        * {@inheritdoc}        */       public function getFormId() {         return 'resume_form';       }        /**        * {@inheritdoc}        */       public function buildForm(array $form, FormStateInterface $form_state) {          $form['number1'] = array(           '#type' => 'textfield',           '#title' => t('number 1'),           '#required' => TRUE,         );          $form['number2'] = array(           '#type' => 'textfield',           '#title' => t('number 2'),           '#required' => TRUE,         );          $form['actions']['#type'] = 'actions';         $form['actions']['submit'] = array(           '#type' => 'submit',           '#value' => $this->t('Save'),           '#button_type' => 'primary',         );    $header = array(     'total',   );   $output = array();   foreach ($form_state->getValues() as $key => $value) {      $output['total'] = $total;   }   $form['mytable'] = array(     '#type' => 'table',     '#header' => $header,     '#rows' => $output,     '#empty' => t('No Data'),   );          return $form;       }         /**        * {@inheritdoc}        */       public function submitForm(array &$form, FormStateInterface $form_state) {          foreach ($form_state->getValues() as $key => $value) {           drupal_set_message($key . ': ' . $value);         }  $total = $form_state->getValue('number1') * $form_state->getValue('number2');      $form_state->setValue('total',array($total));             }         }