statemixin.dart

import 'package:flutter/material.dart';
import 'package:get/get.dart';

class Controller extends GetxController with StateMixin<String> {
  final String changeThis = 'Super Cool String';

  @override
  Future<void> onInit() async {
    await Future.delayed(2.seconds); //To see the loading
    change(changeThis, status: RxStatus.success());

    await Future.delayed(10.seconds); //To wait before showing empty
    change(changeThis, status: RxStatus.loading());
    await Future.delayed(5.seconds); //To see the loading
    change(
      null,
      status: RxStatus.empty(),
    ); //To Show Empty

    await Future.delayed(10.seconds); //To wait before showing error
    change(changeThis, status: RxStatus.loading());
    await Future.delayed(5.seconds); //To see the loading
    change(
      changeThis,
      status: RxStatus.error('Sorry I don\'t know what the error is'),
    ); //To Show Error
    super.onInit();
  }
}

class View extends GetView<Controller> {
  const View({Key key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return controller.obx(
      (state) => ListTile(
        title: Text(state),
      ),
      onEmpty: ListTile(
        //For Custom Empty Widget
        title: Text('I am totally empty'),
      ),
      onError: (error) => ListTile(
        //For Custom Error Messege
        title: Text(error),
      ),
      onLoading: ListTile(
        //For Custom Loading
        title: Align(
          alignment: Alignment.centerLeft,
          child: CircularProgressIndicator(),
        ),
      ),
    );
  }
}