Flutter报错LateInitializationError: currentPosition未初始化如何解决？

• late关键字修饰的变量意味着你承诺会在首次访问它之前完成赋值，且该变量不可为空。你在build方法中直接执行currentposition != null判空操作时，此时还没触发Locate me按钮点击、或者定位异步方法还未执行完赋值操作，相当于提前访问了未初始化的late变量，哪怕只是判空也会直接抛出LateInitializationError。
• 额外补充：你的权限校验逻辑存在漏洞，当定位服务未开启、权限被拒绝时，代码只会弹出Toast，依旧会向下执行获取定位的逻辑，极端情况下也会导致currentposition赋值失败。

1. 移除currentposition的late修饰符，改为可空类型声明，默认初始值为null，此时判空操作就不会触发未初始化错误：

// 替换原有的 late Position currentposition;
Position? currentposition;

2. 完善权限校验逻辑，异常情况下直接终止方法执行，避免后续无效逻辑报错：

import 'package:flutter/material.dart';
import 'package:fluttertoast/fluttertoast.dart';
import 'package:geocoding/geocoding.dart';
import 'package:geolocator/geolocator.dart';

class Home extends StatefulWidget {
  @override
  _HomeState createState() => _HomeState();
}

class _HomeState extends State<Home> {

  String currentAddress = '我的地址';
  Position? currentposition ;
  Future<Position?> _determinePosition() async {
    bool serviceEnabled;
    LocationPermission permission;

    serviceEnabled = await Geolocator.isLocationServiceEnabled();
    if (!serviceEnabled) {
      Fluttertoast.showToast(msg: '请开启定位服务');
      return null;
    }

    permission = await Geolocator.checkPermission();
    if (permission == LocationPermission.denied) {
      permission = await Geolocator.requestPermission();
      if (permission == LocationPermission.denied) {
        Fluttertoast.showToast(msg: '定位权限被拒绝');
        return null;
      }
    }

    if (permission == LocationPermission.deniedForever) {
      Fluttertoast.showToast(
          msg:
          '定位权限被永久拒绝，无法申请权限');
      return null;
    }

    Position position = await Geolocator.getCurrentPosition(
        desiredAccuracy: LocationAccuracy.high);

    try {
      List<Placemark> placemarks =
      await placemarkFromCoordinates(position.latitude, position.longitude);

      Placemark place = placemarks[0];

      setState(() {
        currentposition = position;
        currentAddress =
        "${place.locality}, ${place.subLocality},${place.street}, ${place.postalCode}";
      });
    } catch (e) {
      print(e);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('我的定位'),
      ),
      body: Center(
          child: Column(
            children: [
              Text(currentAddress),
              currentposition != null
                  ? Text('纬度 = ' + currentposition!.latitude.toString())
                  : Container(),
              currentposition != null
                  ? Text('经度 = ' + currentposition!.longitude.toString())
                  : Container(),
              TextButton(
                  onPressed: () {
                    _determinePosition();
                  },
                  child: Text('获取我的位置'))
            ],
          ),),
    );
  }
}

3. 可空类型变量访问时添加!非空断言即可，原有UI显示逻辑无需大幅调整。

内容的提问来源于stack exchange，提问作者Shubham_Kr