FutureBuilderのサンプル

Future2.dart

import 'dart:async';

import 'package:flutter/material.dart';

class FutureRefresh7 extends StatefulWidget {
  const FutureRefresh7({super.key});

  @override
  State<FutureRefresh7> createState() => _FutureRefresh7State();
}

class _FutureRefresh7State extends State<FutureRefresh7> {
  late Future<void> future;

  static Future<void> generateSupply(int loop) async {
    for (int i = 0; i < loop; i++) {
      await Future.delayed(const Duration(milliseconds: 1));
      if ((i % 100) == 0) {
        debugPrint("$i");
      }
    }
    debugPrint("Done");
  }

  @override
  void initState() {
    future = generateSupply(1000);
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("FutureRefresh"),
      ),
      body: FutureBuilder<void>(
        future: future,
        builder: (context, snapshot) {
          switch (snapshot.connectionState) {
            case ConnectionState.none:
              return const Center(child: Text("none"));
            case ConnectionState.waiting:
              return Container(
                  alignment: Alignment.center,
                  child: const CircularProgressIndicator());
            case ConnectionState.active:
              return const Center(child: Text("active"));
            case ConnectionState.done:
              return const Center(child: Text("done"));
          }
        },
      ),
    );
  }
}