参数类型“int”不能分配给参数类型“double”

Posted 2023-02-23

【中文标题】参数类型“int”不能分配给参数类型“double”

【英文标题】：The argument type 'int' can't be assigned to the parameter type 'double'

【发布时间】：2021-03-23 23:59:13

【问题描述】：

谁能帮助我我正在尝试为电池百分比制作一个圆形百分比指标，但我收到了这个错误，这是我的大学项目工作，第一次写这篇文章我以前从未这样做过，我在编码方面也是新手。

lib/pages/device_dashboard.dart:139:36：错误：。 百分比：_batteryLevel， ^

这是我的代码

import 'dart:async';
import 'package:flutter/cupertino.dart';
import 'package:percent_indicator/percent_indicator.dart';
import 'package:battery/battery.dart';
import 'package:flutter/material.dart';

class DeviceDashboard extends StatefulWidget 
  @override
  _DeviceDashboardState createState() => _DeviceDashboardState();


class _DeviceDashboardState extends State<DeviceDashboard> 
  Battery _battery = Battery();
  BatteryState _batteryState;

  int _batteryLevel;

  StreamSubscription<BatteryState> _batteryStateSubscription;
 

  @override
  void initState() 
    super.initState();
    _batteryStateSubscription =
        _battery.onBatteryStateChanged.listen((BatteryState state) 
      setState(() 
        _batteryState = state;
      );
    );
  

  Future<void> _getLevel() async 
    final batteryLevel = await _battery.batteryLevel;
    setState(() 
      _batteryLevel = batteryLevel;
    );
  

  @override
  void dispose() 
    // TODO: implement dispose
    super.dispose();
    if (_batteryStateSubscription != null) 
      _batteryStateSubscription.cancel();
    
  

  @override
  Widget build(BuildContext context) 
    return Scaffold(
      appBar: AppBar(
        title: Text('Device Dashboard'),
        ),
      body: SingleChildScrollView(
        child: Column(
          children: <Widget>[
            SizedBox(
              height: 50,
            ),
            Text(
              '$_batteryState',
              style: TextStyle(
                fontSize: 18,
                fontWeight: FontWeight.bold,
                color: Colors.grey[400],
              ),
            ),

            Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                CircularPercentIndicator(
                  radius: 100.0,
                  lineWidth: 7.0,
                  center: MaterialButton(
                    onPressed: _getLevel,
                    textColor: Colors.white,
                    child: Text(
                      '$_batteryLevel %',
                      style: TextStyle(
                          color: Colors.white,
                          fontWeight: FontWeight.bold,
                          fontSize: 20),
                    ),
                    padding: EdgeInsets.all(20),
                    shape: CircleBorder(),
                  ),
                  progressColor: Colors.green,
                  percent: 0.5, // after putting _batteryLevel here i m getting that error 
                ),
                Text(
                  'Battery',
                  style: TextStyle(
                    fontSize: 20,
                    fontWeight: FontWeight.bold,
                    color: Colors.white,
                  ),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  

【参考方案1】：

如果您想向用户显示十进制值，Ketan Ramteke 的回答是正确的。 如果这不是您想要的，您可以保留变量 int（就像您目前拥有的那样），然后将电池双倍水平四舍五入，使其为 int 而不是双倍，您应该不会再收到此错误：

Future<void> _getLevel() async 
final batteryLevel = await _battery.batteryLevel;
setState(() 
  _batteryLevel = batteryLevel.round();
);

【讨论】：

Ketan Ramteke，即使在更改 double _batteryLevel; //<= declare it as a double instead of int //.... Future<void> _getLevel() async final batteryLevel = await _battery.batteryLevel; setState(() _batteryLevel = batteryLevel; ); 之后也无法正常工作，但现在它向我显示了不同的错误 在构建 DeviceDashboard(dirty, state: _DeviceDashboardState#bfe3e): The method '

Luis Utrera，现在再次工作，Future<void> _getLevel() async final batteryLevel = await _battery.batteryLevel; setState(() _batteryLevel = batteryLevel.round(); ); 但得到相同的错误 在构建 DeviceDashboard(dirty, state: _DeviceDashboardState#bfe3e) 时引发了以下 NoSuchMethodError：调用了方法 '

即使在我更改后也无法正常工作，double _batteryLevel; Future<void> _getLevel() async final batteryLevel = await _battery.batteryLevel; setState(() _batteryLevel = batteryLevel.roundToDouble(); ); , or _batteryLevel = batteryLevel as double;

and `percent: 0.5, //这应该在0.0到1.0之间