displaying_the_battery_state_in_a_string_and_a_button.js

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

import 'package:flutter/services.dart';
import 'package:batteryLevel/batteryLevel.dart';

void main() {
  runApp(MaterialApp(home: MyApp()));
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  String _batteryLevel = 'Unknown';

  @override
  void initState() {
    super.initState();
  }

  // Platform messages are asynchronous, so we initialize in an async method.
  Future<void> _getBatteryLevel() async {
    String batteryLevel;
    // Platform messages may fail, so we use a try/catch PlatformException.
    try {
      batteryLevel = await BatteryLevel.getBatteryLevel();
    } on PlatformException {
      batteryLevel = 'Failed to get platform version.';
    }

    // If the widget was removed from the tree while the asynchronous platform
    // message was in flight, and we want to discard the reply rather than calling
    // setState to update our non-existent appearance.
    if (!mounted) return;

    setState(() {
      _batteryLevel = batteryLevel;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Material(
      child: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          children: [
            ElevatedButton(
              child: Text('Get Battery Level'),
              onPressed: _getBatteryLevel,
            ),
            Text(_batteryLevel),
          ],
        ),
      ),
    );
  }
}