Flutter SetState不使用listview.builder
我这里有一些用于应用程序聊天屏幕的代码。此特定聊天屏幕用于与机器人聊天。机器人应该在用户发送每条消息之后发送一条消息。由bot发送的消息列表存储在messageStrings中。我正在使用listview.builder使用添加到消息列表中的新消息填充UI 我正在使用setstate添加新消息,但UI没有使用新消息进行更新。这是我的代码:Flutter SetState不使用listview.builder,flutter,listview,flutter-layout,setstate,Flutter,Listview,Flutter Layout,Setstate,我这里有一些用于应用程序聊天屏幕的代码。此特定聊天屏幕用于与机器人聊天。机器人应该在用户发送每条消息之后发送一条消息。由bot发送的消息列表存储在messageStrings中。我正在使用listview.builder使用添加到消息列表中的新消息填充UI 我正在使用setstate添加新消息,但UI没有使用新消息进行更新。这是我的代码: import 'package:flutter/cupertino.dart'; import 'package:flutter/material.dart'
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import '../models/chats.dart';
class ReportPage extends StatefulWidget {
BuildContext context;
ReportPage(this.context);
@override
_ReportPageState createState() => _ReportPageState();
}
class _ReportPageState extends State<ReportPage> {
@override
Widget build(Object context) {
TextEditingController messageContoller = new TextEditingController();
//The first two messages by the bot are already added to the List
List<ChatMessage> messages = [
ChatMessage(messageContent: "Message 1", messageType: "receiver"),
ChatMessage(messageContent: "Message 2", messageType: "receiver"),
];
int messageIndex = 0;
//The next messages that are to be added to the list after a response from the user
List<String> messageStrings = ["Message 3", "Message 4","Message 5",];
return Scaffold(
appBar: AppBar(
title: Row(children: [
Container(
width: 35,
height: 35,
child: Image.asset(
'assets/images/police.png',
fit: BoxFit.cover,
),
decoration:
BoxDecoration(shape: BoxShape.circle, color: Colors.white),
),
SizedBox(
width: 10,
),
Text("CFB bot"),
]),
),
body: Container(
padding: EdgeInsets.all(20),
child: Stack(
children: <Widget>[
ListView.builder(
itemCount: messages.length,
shrinkWrap: true,
padding: EdgeInsets.only(top: 10, bottom: 10),
physics: NeverScrollableScrollPhysics(),
itemBuilder: (context, index) {
return Container(
padding:
EdgeInsets.only(left: 14, right: 14, top: 10, bottom: 10),
child: Align(
alignment: (messages[index].messageType == "receiver"
? Alignment.topLeft
: Alignment.topRight),
child: Container(
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(20),
color: (messages[index].messageType == "receiver"
? Colors.grey.shade200
: Colors.blue[200]),
),
padding: EdgeInsets.all(16),
child: Text(
messages[index].messageContent,
style: TextStyle(fontSize: 15),
),
),
),
);
},
),
Align(
alignment: Alignment.bottomLeft,
child: Container(
decoration: BoxDecoration(
border: Border.all(color: Colors.black),
borderRadius: BorderRadius.all(Radius.circular(20))),
padding: EdgeInsets.only(left: 10, bottom: 10, top: 10),
height: 60,
width: double.infinity,
child: Row(
children: <Widget>[
GestureDetector(
onTap: () {},
child: Container(
height: 30,
width: 30,
decoration: BoxDecoration(
color: Colors.lightBlue,
borderRadius: BorderRadius.circular(30),
),
child: Icon(
Icons.add,
color: Colors.white,
size: 20,
),
),
),
SizedBox(
width: 15,
),
Expanded(
child: TextField(
decoration: InputDecoration(
hintText: "Write message...",
hintStyle: TextStyle(color: Colors.black54),
border: InputBorder.none),
controller: messageContoller,
),
),
SizedBox(
width: 15,
),
FloatingActionButton(
onPressed: () {
String message = messageContoller.text;
setState(() {
messages.add(ChatMessage(messageContent: message, messageType: "sender"));
messages.add(ChatMessage(messageContent: messageStrings[messageIndex], messageType: "receiver"));
});
messageIndex++;
for(int i = 0; i < messages.length; i++){
print(messages[i].messageContent);
}
},
child: Icon(
Icons.send,
color: Colors.white,
size: 18,
),
backgroundColor: Colors.blue,
elevation: 0,
),
],
),
),
),
],
),
),
);
}
}
import'包装:flift/cupertino.dart';
进口“包装:颤振/材料.省道”;
导入“../models/chats.dart”;
类ReportPage扩展了StatefulWidget{
构建语境;
报告页(本.上下文);
@凌驾
_ReportPageState createState()=>ReportPageState();
}
类_ReportPageState扩展状态{
@凌驾
小部件构建(对象上下文){
TextEditingController messageContoller=新的TextEditingController();
//bot发送的前两条消息已添加到列表中
列表消息=[
ChatMessage(messageContent:“Message 1”,messageType:“receiver”),
ChatMessage(messageContent:“Message 2”,messageType:“receiver”),
];
int messageIndex=0;
//用户响应后要添加到列表中的下一条消息
列表消息字符串=[“消息3”、“消息4”、“消息5”、];
返回脚手架(
appBar:appBar(
标题:世界其他地区(儿童:[
容器(
宽度:35,
身高:35,
子:Image.asset(
“assets/images/police.png”,
适合:BoxFit.cover,
),
装饰:
盒子装饰(形状:盒子形状。圆圈,颜色:颜色。白色),
),
大小盒子(
宽度:10,
),
文本(“CFB bot”),
]),
),
主体:容器(
填充:边缘设置。全部(20),
子:堆栈(
儿童:[
ListView.builder(
itemCount:messages.length,
收缩膜:对,
填充:仅限边缘设置(顶部:10,底部:10),
物理学:NeverscrollableScroll物理学(),
itemBuilder:(上下文,索引){
返回容器(
衬垫:
仅限边集(左:14,右:14,顶部:10,底部:10),
子对象:对齐(
对齐:(消息[索引]。消息类型==“接收者”
?左上角对齐
:对齐。右上角),
子:容器(
装饰:盒子装饰(
边界半径:边界半径。圆形(20),
颜色:(消息[索引]。消息类型==“接收者”
?颜色。灰色。阴影200
:Colors.blue[200]),
),
填充:边缘设置。全部(16),
子:文本(
消息[索引]。消息内容,
样式:TextStyle(字体大小:15),
),
),
),
);
},
),
对齐(
对齐:对齐。左下角,
子:容器(
装饰:盒子装饰(
边框:边框。全部(颜色:颜色。黑色),
borderRadius:borderRadius.all(半径.圆形(20)),
填充:仅限边设置(左:10,下:10,上:10),
身高:60,
宽度:double.infinity,
孩子:排(
儿童:[
手势检测器(
onTap:(){},
子:容器(
身高:30,
宽度:30,
装饰:盒子装饰(
颜色:颜色。浅蓝色,
边界半径:边界半径。圆形(30),
),
子:图标(
Icons.add,
颜色:颜色,白色,
尺码:20,
),
),
),
大小盒子(
宽度:15,
),
扩大(
孩子:TextField(
装饰:输入装饰(
hintText:“写消息…”,
hintStyle:TextStyle(颜色:Colors.black54),
边框:InputBorder.none),
控制器:messagecontroller,
),
),
大小盒子(
宽度:15,
),
浮动操作按钮(
已按下:(){
字符串message=messageContoller.text;
设置状态(){
messages.add(ChatMessage(messageContent:message,messageType:sender));
添加(ChatMessage(messageContent:messageStrings[messageIndex],messageType:“receiver”);
});
messageIndex++;
for(int i=0;imessages = [
...messages,
ChatMessage(messageContent: message, messageType: "sender"),
ChatMessage(messageContent: messageStrings[messageIndex], messageType: "receiver")
];