flutter Error: Couldn't find constructor 'HomePage'.

Question

実現したいこと

https://www.geeksforgeeks.org/how-to-get-users-current-location-on-google-maps-in-flutter/

• このサイトの通りを動作するようにする

前提

main.dartの
'package:google_maps/HomePage.dart';
HomePage(),
Homepage.dartの
_marker
の部分が赤線になってしまします。どうすればえらーをはかずにじっこうすることができるのでしょうか？

発生している問題・エラーメッセージ

Launching lib\main.dart on sdk gphone64 x86 64 in debug mode...
Running Gradle task 'assembleDebug'...
Invalid depfile: C:\Users\kouki\AndroidStudioProjects\mapsecond\.dart_tool\flutter_build\cb6670808a35f1e334b20c87c0941213\kernel_snapshot.d
Invalid depfile: C:\Users\kouki\AndroidStudioProjects\mapsecond\.dart_tool\flutter_build\cb6670808a35f1e334b20c87c0941213\kernel_snapshot.d
Error: Couldn't resolve the package 'google_maps' in 'package:google_maps/HomePage.dart'.
lib/main.dart:2:8: Error: Not found: 'package:google_maps/HomePage.dart'
import 'package:google_maps/HomePage.dart';
       ^
lib/main.dart:24:19: Error: Couldn't find constructor 'HomePage'.
      home: const HomePage(),
                  ^^^^^^^^
U
nhandled exception:
FileSystemException(uri=org-dartlang-untranslatable-uri:package%3Agoogle_maps%2FHomePage.dart; message=StandardFileSystem only supports file:
* and data:* URIs)
#0      StandardFileSystem.entityForUri (package:front_end/src/api_prototype/standard_file_system.dart:34:7)
#1      asFileUri (package:vm/kernel_front_end.dart:659:37)
#2      writeDepfile (package:vm/kernel_front_end.dart:799:21)
<asynchronous suspension>
#3      FrontendCompiler.compile (package:frontend_server/frontend_server.dart:625:9)
<asynchronous suspension>
#4 
     starter (package:frontend_server/frontend_server.dart:1451:12)
<asynchronous suspension>
#5      main (file:///C:/b/s/w/ir/x/w/sdk/pkg/frontend_server/bin/
frontend_server_starter.dart:10:14)
<asynchronous suspension>



FAILURE: Build failed with an exception.

* Where:
Script 'C:\src\flutter\packages\flutter_tools\gradle\flutter.gradle' line: 1159

* What went wrong:
Execution failed for task ':app:compileFlutterBuildDebug'.
> Process 'command 'C:\src\flutter\bin\flutter.bat'' finished with non-zero exit value 1

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 10s
Exception: Gradle task assembleDebug failed with exit code 1

該当のソースコード

import 'package:flutter/material.dart';
import 'package:google_maps/HomePage.dart';

void main() {
runApp(const MyApp());
}

class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);

// This widget is the root of your application.
@override
Widget build(BuildContext context) {
	return MaterialApp(
	// on below line we are specifying title of our app
	title: 'GFG',
	// on below line we are hiding debug banner
	debugShowCheckedModeBanner: false,
	theme: ThemeData(
		// on below line we are specifying theme
		primarySwatch: Colors.green,
	),
	// First screen of our app
	home: const HomePage(),
	);
}
}

該当のソースコード

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

class HomePage extends StatefulWidget {
const HomePage({Key? key}) : super(key: key);

@override
_HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
Completer<GoogleMapController> _controller = Completer();
// on below line we have specified camera position
static final CameraPosition _kGoogle = const CameraPosition(
	target: LatLng(20.42796133580664, 80.885749655962),
	zoom: 14.4746,
);

// on below line we have created the list of markers
final List<Marker> _markers = <Marker>[
	Marker(
		markerId: MarkerId('1'),
	position: LatLng(20.42796133580664, 75.885749655962),
	infoWindow: InfoWindow(
		title: 'My Position',
	)
),
];

// created method for getting user current location
Future<Position> getUserCurrentLocation() async {
	await Geolocator.requestPermission().then((value){
	}).onError((error, stackTrace) async {
	await Geolocator.requestPermission();
	print("ERROR"+error.toString());
	});
	return await Geolocator.getCurrentPosition();
}

@override
Widget build(BuildContext context) {
	return Scaffold(
	appBar: AppBar(
		backgroundColor: Color(0xFF0F9D58),
		// on below line we have given title of app
		title: Text("GFG"),
	),
	body: Container(
		child: SafeArea(
		// on below line creating google maps
		child: GoogleMap(
		// on below line setting camera position
		initialCameraPosition: _kGoogle,
		// on below line we are setting markers on the map
		markers: Set<Marker>.of(_marker),
		// on below line specifying map type.
		mapType: MapType.normal,
		// on below line setting user location enabled.
		myLocationEnabled: true,
		// on below line setting compass enabled.
		compassEnabled: true,
		// on below line specifying controller on map complete.
		onMapCreated: (GoogleMapController controller){
				_controller.complete(controller);
			},
		),
		),
	),
	// on pressing floating action button the camera will take to user current location
	floatingActionButton: FloatingActionButton(
		onPressed: () async{
		getUserCurrentLocation().then((value) async {
			print(value.latitude.toString() +" "+value.longitude.toString());

			// marker added for current users location
			_markers.add(
				Marker(
				markerId: MarkerId("2"),
				position: LatLng(value.latitude, value.longitude),
				infoWindow: InfoWindow(
					title: 'My Current Location',
				),
				)
			);

			// specified current users location
			CameraPosition cameraPosition = new CameraPosition(
			target: LatLng(value.latitude, value.longitude),
			zoom: 14,
			);

			final GoogleMapController controller = await _controller.future;
			controller.animateCamera(CameraUpdate.newCameraPosition(cameraPosition));
			setState(() {
			});
		});
		},
		child: Icon(Icons.local_activity),
	),
	);
}
}

補足情報（FW/ツールのバージョンなど）

main.dartの
'package:google_maps/HomePage.dart';
HomePage(),
Homepage.dartの
_marker
の部分が赤線になってしまします。どうすればえらーをはかずにじっこうすることができるのでしょうか？