flutter - 如何为 DropDownMenu 添加另一个项目列表,然后使用小部件中的项目
问题描述
所以我试图为每个选项制作一个下拉菜单,并为每个选项插入一个不同的项目列表。首先,因为我的 Dropdownmenu 小部件彼此共享相同的属性,所以我将小部件提取到另一个类名“MenuDropDown”。这是小部件的代码。
import 'package:flutter/material.dart';
import 'List.dart';
class MenuDropDown extends StatefulWidget {
final String dropdownText;
final List<DropdownMenuItem<String>> itemList;
MenuDropDown({this.dropdownText, this.itemList});
@override
_MenuDropDownState createState() => _MenuDropDownState();
}
class _MenuDropDownState extends State<MenuDropDown> {
String selectedItem;
List<DropdownMenuItem> getGroomingTypeList() {
List<DropdownMenuItem<String>> dropdownItems = [];
for (String groomingType in groomingTypeList) {
var newItem = DropdownMenuItem(
child: Text(groomingType),
value: groomingType,
);
dropdownItems.add(newItem);
}
return dropdownItems;
}
List<DropdownMenuItem> getCatBreedsList() {
List<DropdownMenuItem<String>> dropdownItems = [];
for (String catBreed in catBreedsList) {
var newItem = DropdownMenuItem(
child: Text(catBreed),
value: catBreed,
);
dropdownItems.add(newItem);
}
return dropdownItems;
}
@override
Widget build(BuildContext context) {
return Padding(
padding: const EdgeInsets.fromLTRB(0, 8.0, 0, 10.0),
child: Container(
width: 325.0,
height: 50.0,
decoration: BoxDecoration(
boxShadow: [
BoxShadow(
color: Colors.black45,
offset: Offset(2.5, 5.5),
blurRadius: 5.0,
)
],
borderRadius: BorderRadius.circular(8),
color: Colors.white,
),
child: DropdownButtonHideUnderline(
child: DropdownButton(
value: selectedItem,
hint: Padding(
padding: const EdgeInsets.fromLTRB(22.0, 0, 0, 0),
child: Text(
widget.dropdownText,
style: TextStyle(),
),
),
items: widget.itemList,
onChanged: (value) {
setState(() {
selectedItem = value;
});
}),
),
),
);
}
}
上面这里我创建了一个从我已经创建的列表类中获取列表项的方法,首先,如果我将该方法硬编码到下拉菜单的项目属性中以显示项目列表,它会起作用,但是因为我需要使用不同的列表不同的小部件,所以我想如果我尝试创建一个名为 itemList 的 List 变量,那么我可以从另一个类访问它,我可以只调用自定义变量。
这是我使用 Extracted Dropdownmenu 小部件的 Stateful 小部件:
import 'package:flutter/material.dart';
import 'TitleName.dart';
import 'dropdownmenu.dart';
class InformationDetail extends StatefulWidget {
@override
_InformationDetailState createState() => _InformationDetailState();
}
class _InformationDetailState extends State<InformationDetail> {
MenuDropDown _menuDropDown = MenuDropDown();
@override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: Container(
child: Column(
children: <Widget>[
Container(
margin: EdgeInsets.fromLTRB(25.0, 68.0, 70.0, 26.0),
child: Text(
'Information Detail',
style: TextStyle(fontSize: 35.0),
),
),
Column(
// Wrap Column
children: <Widget>[
Column(
children: <Widget>[
TitleName(
titleText: 'Grooming Type',
infoIcon: Icons.info,
),
MenuDropDown(
dropdownText: 'Grooming Type...',
//I'm trying to implement the list here with a custom variable that contain
a method with different list in dropdownmenu class
itemlist: getGroomingTypeList(),
),
TitleName(
titleText: 'Cat Breeds',
),
MenuDropDown(
dropdownText: 'Cat Breeds...',
),
TitleName(
titleText: 'Cat Size',
infoIcon: Icons.info,
),
MenuDropDown(
dropdownText: 'Cat Size...',
),
TitleName(
titleText: 'Add-On Services',
),
MenuDropDown(
dropdownText: 'Add - On Services...',
),
Container(
margin: EdgeInsets.fromLTRB(0, 15.0, 0, 0),
width: 75.0,
decoration: BoxDecoration(
color: Colors.white,
shape: BoxShape.rectangle,
border: Border.all(
color: Colors.black,
),
borderRadius: BorderRadius.circular(12.0),
),
child: IconButton(
icon: Icon(Icons.arrow_forward),
onPressed: () {
Navigator.of(context)
.pushNamed('/ReservationDetail');
},
),
),
],
),
],
),
],
),
),
),
);
}
}
这是我要用于每个下拉菜单小部件的列表
const List groomingTypeList = ['Basic Grooming', 'Full Grooming'];
const List catBreedsList = [
'Persia',
'Anggora',
'Domestic',
'Maine Coon',
'Russian Blue',
'Slamese',
'Munchkin',
'Ragdoll',
'Scottish Fold',
];
const List catSizeList = [
'Small Size',
'Medium Size',
'Large Size',
'Extra Large Size',
];
const List addOnServicesList = [
'Spa & Massage',
'Shaving Hair / Styling',
'Injection Vitamis Skin & Coat',
'Cleaning Pet House and Environment',
'Fur Tangled Treatment',
];
我从那里卡住了。如何为我制作的每个下拉菜单小部件使用不同的列表,因为我已经尝试制作构造函数、变量和方法,因此我可以单独使用它,但是我得到了一个错误消息,
“List”类型不是“List<DropdownMenuItem>”类型的子类型
我想我一开始就以错误的方式实现了它。我真的需要帮助来解决这些问题。谢谢大家!
解决方案
只需查看我进行了一些更改的代码:
import 'package:flutter/material.dart';
void main() => runApp(InformationDetail());
class InformationDetail extends StatefulWidget {
@override
_InformationDetailState createState() => _InformationDetailState();
}
class _InformationDetailState extends State<InformationDetail> {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: SafeArea(
child: Container(
child: Column(
children: <Widget>[
Container(
margin: EdgeInsets.fromLTRB(25.0, 68.0, 70.0, 26.0),
child: Text(
'Information Detail',
style: TextStyle(fontSize: 35.0),
),
),
Column(
// Wrap Column
children: <Widget>[
Column(
children: <Widget>[
Text(
'Grooming Type',
),
MenuDropDown(
dropdownText: 'Grooming Type...',
//I'm trying to implement the list here with a custom variable that contain
// a method with different list in dropdownmenu class
type: "groomingType",
),
Text(
'Cat Breeds',
),
MenuDropDown(
dropdownText: 'Cat Breeds...',
type: "catBreeds",
),
Text(
'Cat Size',
),
MenuDropDown(
dropdownText: 'Cat Size...',
type: "catSize",
),
Text(
'Add-On Services',
),
MenuDropDown(
dropdownText: 'Add - On Services...',
type: "addOnServices",
),
Container(
margin: EdgeInsets.fromLTRB(0, 15.0, 0, 0),
width: 75.0,
decoration: BoxDecoration(
color: Colors.white,
shape: BoxShape.rectangle,
border: Border.all(
color: Colors.black,
),
borderRadius: BorderRadius.circular(12.0),
),
child: IconButton(
icon: Icon(Icons.arrow_forward),
onPressed: () {
Navigator.of(context)
.pushNamed('/ReservationDetail');
},
),
),
],
),
],
),
],
),
),
),
),
);
}
}
class MenuDropDown extends StatefulWidget {
final String dropdownText;
final String type;
MenuDropDown({this.dropdownText, this.type});
@override
_MenuDropDownState createState() => _MenuDropDownState();
}
class _MenuDropDownState extends State<MenuDropDown> {
String selectedItem;
List<String> dropdownItems = [];
List<String> groomingTypeList = ['Basic Grooming', 'Full Grooming'];
List<String> catBreedsList = [
'Persia',
'Anggora',
'Domestic',
'Maine Coon',
'Russian Blue',
'Slamese',
'Munchkin',
'Ragdoll',
'Scottish Fold',
];
List<String> catSizeList = [
'Small Size',
'Medium Size',
'Large Size',
'Extra Large Size',
];
List<String> addOnServicesList = [
'Spa & Massage',
'Shaving Hair / Styling',
'Injection Vitamis Skin & Coat',
'Cleaning Pet House and Environment',
'Fur Tangled Treatment',
];
List<String> getListBasedOnName(String value) {
print(value);
switch (value) {
case "groomingType":
return groomingTypeList;
break;
case "catBreeds":
return catBreedsList;
break;
case "catSize":
return catSizeList;
break;
case "addOnServices":
return addOnServicesList;
break;
}
return null;
}
@override
void initState() {
super.initState();
print(widget.type);
dropdownItems = getListBasedOnName(widget.type);
}
@override
Widget build(BuildContext context) {
return Padding(
padding: const EdgeInsets.fromLTRB(0, 8.0, 0, 10.0),
child: Container(
width: 325.0,
height: 50.0,
decoration: BoxDecoration(
boxShadow: [
BoxShadow(
color: Colors.black45,
offset: Offset(2.5, 5.5),
blurRadius: 5.0,
)
],
borderRadius: BorderRadius.circular(8),
color: Colors.white,
),
child: DropdownButtonHideUnderline(
child: DropdownButton(
value: selectedItem,
hint: Padding(
padding: const EdgeInsets.fromLTRB(22.0, 0, 0, 0),
child: Text(
widget.dropdownText,
style: TextStyle(),
),
),
items: dropdownItems.map((String value) {
return new DropdownMenuItem<String>(
value: value,
child: new Text(value),
);
}).toList(),
onChanged: (value) {
setState(() {
selectedItem = value;
});
}),
),
),
);
}
}
由于缺少一些小部件,我添加了我的,您可以根据需要进行更改。让我知道它是否有效。