小编dm_*_*_tr的帖子

好了，所以我跑我的程序不导入火力核心，火力权威性和云公司的FireStore，我的代码运行得很好，但我与火力注册我的应用程序，它仍然运行良好，但只要我进口Firebase_auth，Firebase_core和cloud_Firestore...我得到以下错误

Note: C:\appflutter\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_core-0.7.0\android\src\main\java\io\flutter\plugins\firebase\core\FlutterFirebaseCorePlugin.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: C:\appflutter\flutter\.pub-cache\hosted\pub.dartlang.org\cloud_firestore-0.16.0\android\src\main\java\io\flutter\plugins\firebase\firestore\streamhandler\TransactionStreamHandler.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
D8: Cannot fit requested classes in a single dex file (# methods: 89543 > 65536)
com.android.builder.dexing.DexArchiveMergerException: Error while merging dex archives: 
The number of method references in a .dex file cannot exceed 64K.

请帮我。

import 'package:flutter/material.dart';

void main() {
  runApp(Calculator());
}

class Calculator extends StatelessWidget {
  final numpad_background_color = Color(0x212121);
  final background_color = Colors.black;
  final equal_button_background_color = Color(0xffbe00);

  final textColor = Colors.white;
  final operatorTextColor = Color(0xf3ba0e);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: Scaffold(
            appBar: appbar(context),
            body: Stack(
              children: [Container(height: MediaQuery.of(context).size.height * 0.37), numpad(context)],
            )));
  }

  Widget appbar(BuildContext context) {
    return AppBar(title: Text("Rechner", style: TextStyle(color: textColor, fontSize: 15)), backgroundColor: background_color, leading: Icon(Icons.history));
  }

  Widget numpad(BuildContext context) {
    return Container(decoration: BoxDecoration(borderRadius: BorderRadius.circular(5), color: numpad_background_color), …

我正在使用image_picker 0.6.7+17库以便使用手机摄像头拍摄图像。
我使用的是 android 设备而不是 ios 设备。

一个问题

似乎getImage没有定义该方法，我从文档中获取了这个确切的代码：

  final picker = ImagePicker();

  Future getImage() async {
    final pickedFile = await picker.getImage(source: ImageSource.camera);
  }

我收到此错误：

lib/pickers/image_picker.dart:17:37: Error: The method 'getImage' isn't defined for the class 
'ImagePicker'.
 - 'ImagePicker' is from 'package:chat_app/pickers/image_picker.dart' 
('lib/pickers/image_picker.dart').
Try correcting the name to the name of an existing method, or defining a method named 'getImage'.
final pickedFile = await picker.getImage(source: ImageSource.camera);
                                ^^^^^^^^

到目前为止我做了什么：

• 将依赖项添加到我的 pubspec.yaml: 文件

dependencies:
  flutter:
    sdk: flutter …

您好，我对 Flutter 和软件开发总体来说还很陌生。我似乎无法理解如何从一项活动导航到另一项活动。我真正想要的是，当我按下登录按钮时，它应该将我导航到新活动

void main() {
  runApp(MaterialApp(
    title: 'button navigation',
    home: HomeActivity(),
  ));
}

class HomeActivity extends StatelessWidget{
  gotoSecondActivity(BuildContext context){

    Navigator.push(
      context,
      MaterialPageRoute(builder: (context) => SecondActivity()),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Home Screen'),
      ),

      body: Center(
        child: RaisedButton(
          child: Text('Go To Second Screen'),
          color: Colors.red,
          textColor: Colors.white,
          onPressed: () {
            gotoSecondActivity(context);
          },
        ),
      ),
    );
  }
}
class SecondActivity extends StatelessWidget {

  goBack(BuildContext context){

    Navigator.pop(context);

  }

  @override
  Widget build(BuildContext context) {
    return Scaffold( …