flutter - 如何在颤动中修复类@immutable？

Question

class AppForm extends StatefulWidget {

  final String perusahaan;
  final String alamat;

  AppForm ({this.formKey, this.perusahaanController, this.alamatController, this.perusahaan, this.alamat});
  // Required for form validations
  GlobalKey<FormState> formKey = GlobalKey<FormState>();

  // Handles text onchange
  TextEditingController perusahaanController;
  TextEditingController alamatController;

错误信息：

“此类“AppForm”（或该类继承自的类）被标记为“@immutable”，但其一个或多个实例字段不是最终的：AppForm.formKey、AppForm.perusahaanController、AppForm.alamatController”

如何解决这个问题？

标签： flutter