小编Abd*_*did的帖子

我尝试在另一个类的另一个小部件中返回 MealItem 类的构造函数，我正确地执行了导入，并且得到了这个

错误：未为类型“Iterable”定义运算符“[]”。尝试定义运算符 '[]'.dartundefined_operator

这里是 MealItem 类

import 'package:flutter/material.dart';
import '../models/meal.dart';

class MealItem extends StatelessWidget {
  final String title;
  final String imageUrl;
  final int duration;
  final Complexity complexity;
  final Affordability affordability;

  MealItem(
      this.title,
      this.imageUrl,
      this.duration,
      this.complexity,
      this.affordability
    );
  }
}

这是 CategoryMealsScreen 类中的错误

import 'package:flutter/material.dart';
import '../widgets/meal_item.dart';
import '../models/dummy_data.dart';

class CategoryMealsScreen extends StatelessWidget {
  static const routeName = '/CategoriesScreen';

  //final String categoryId;
  //final String categoryTitle;

  //CategoryMealsScreen(this.categoryId,this.categoryTitle);

  @override
  Widget build(BuildContext context) {
    final routeArgs =
        ModalRoute.of(context).settings.arguments as Map<String, …

我正在尝试使用 LogStash 将 SQL Server 数据复制到 Elasticsearch，实现我自己的名为 sql.conf的配置脚本

我收到以下错误：

WARNING, using JAVA_HOME while Logstash distribution comes with a bundled JDK
Java HotSpot(TM) 64-Bit Server VM warning: Option UseConcMarkSweepGC was deprecated in version 9.0 and will likely be removed in a future release.
Sending Logstash logs to C:/Program Files/Elastic/logstash-7.11.1/logs which is now configured via log4j2.properties
[2021-02-25T14:57:05,899][INFO ][logstash.runner          ] Starting Logstash {"logstash.version"=>"7.11.1", "jruby.version"=>"jruby 9.2.13.0 (2.5.7) 2020-08-03 9a89c94bcc Java HotSpot(TM) 64-Bit Server VM 11.0.10+8-LTS-162 on 11.0.10+8-LTS-162 +indy +jit [mswin32-x86_64]"}
[2021-02-25T14:57:06,132][WARN ][logstash.config.source.multilocal] Ignoring the …

我在使用material.dart库中的Colors.black属性时遇到错误。

错误：无法将“Color”类型的值分配给“String”类型的变量。尝试更改变量的类型，或将右侧类型转换为“String”。

import 'package:flutter/material.dart';

class Category {
  final String id;
  final String title;
  final String color;

  const Category({
    @required this.id, 
    @required this.title, 
    this.color = Colors.black,
    });
}

任何帮助将不胜感激