Flutter 吸气剂';迭代器';在null上调用了。接收者:null尝试调用:迭代器
当我制作复选框数据并将选中的复选框显示到下一个屏幕时,我面临上述错误。我只是在做复制粘贴,我不懂代码Flutter 吸气剂';迭代器';在null上调用了。接收者:null尝试调用:迭代器,flutter,dart,null,Flutter,Dart,Null,当我制作复选框数据并将选中的复选框显示到下一个屏幕时,我面临上述错误。我只是在做复制粘贴,我不懂代码 import 'package:flutter/material.dart'; void main() => runApp(Test()); class Test extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( title: '
import 'package:flutter/material.dart';
void main() => runApp(Test());
class Test extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Select Services',
home: RandomWords(),
);
return Container();
}
}
这是一个无状态小部件
class _RandomWordsState extends State<RandomWords>{
final _suggestions = <String>['this is me1','this is me2','this is me3' ];
final _saved = <String>['this is me1','this is me2','this is me3' ];
final _biggerFont = TextStyle(fontSize: 18.0);
这是剩下的代码
Widget _buildRow(String pair) {
final alreadySaved = _saved.contains(pair);
return ListTile(
title: Text(
pair,
style: _biggerFont,
),
trailing: Icon(
alreadySaved ? Icons.check_box : Icons.check_box_outlined,
color: alreadySaved ? Colors.cyan :null,
),
onTap: (){
setState(() {
if (alreadySaved){
_saved.remove(pair);
}
else{
_saved.add(pair);
}
});
},
);
}
这是一个新的屏幕代码
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Startup Name Generator'),
actions: [
IconButton(icon: Icon(Icons.chevron_right), onPressed: _pushSaved),
],
),
body: _buildSuggestions(),
);
}
}
更新
删除以下行:
if (index >= _suggestions.length) {
_suggestions.addAll(generateWordPairs().take(10));
}
如果您想在以后更改它,请将其添加到_buildSuggestions()函数的顶部
Widget _buildSuggestions() {
_suggestions = <String>['this is me1','this is me2','this is me3'];
return ListView.builder( ...
按如下方式导入:
import 'package:english_words/english_words.dart';
但是我不想输入英语单词。我只想使用自定义字符串@lrsvmb@parveen但是你需要这个包来使用这个函数:generateWordPairs()。take(10)那么如果我想使用一个自定义字符串而我不想使用这个函数“generateWordPairs()。take(10)”@parveen你说的自定义字符串是什么意思?你打了什么?然后使用[“hello”、“test”、“custom_string”]代替函数。那么它应该是这样的:_suggestions.addAll([“hello”,…]);当我应用这个“_suggestions.addAll([“hello”,…])”时,“hello”在无限时间内打印。我只想打印字符串值“final _suggestions=[‘this is me1’、‘this is me2’、‘this is me3’]”
Widget _buildSuggestions() {
_suggestions = <String>['this is me1','this is me2','this is me3'];
return ListView.builder( ...
english_words: ^4.0.0
import 'package:english_words/english_words.dart';