type 'List<dynamic>' is not a subtype of type 'Uint8List

android flutter dart flutter-dependencies dart-pub

1,395

I have found a silly solution and I don't know why this is working!

Just insert _json[index]['icon'] into a variable and then use it inside Image.memory() that's it.

var icon = `_json[index]['icon']` ;

Image.memory(icon)

Here is the full code :


import 'dart:async';
import 'dart:convert';
import 'dart:ffi';
import 'dart:io';
import 'dart:typed_data';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
import 'package:device_apps/device_apps.dart';
import 'package:app_settings/app_settings.dart';
import 'package:flutter/services.dart' show rootBundle;

void main() {
  runApp(
    MaterialApp(
      title: 'Reading and Writing Files',
      home: MyApp(),
    ),
  );
}

const String dataFile = 'data1.json';

class MyApp extends StatefulWidget {
  @override
  _AppState createState() => _AppState();
}

class _AppState extends State<MyApp> {
  String data;

  File _filePath;
  bool _fileExists = false;
  String jsonString;

  List<dynamic> _json = [];
  List<dynamic> _jsonshow = [];

  List<Application> appsDetail;

  void checkFile() async {
    // chek if file exists
    String dir = (await getApplicationDocumentsDirectory()).path;
    String savePath = '$dir/$dataFile';

//for a directory: await Directory(savePath).exists();
    if (await File(savePath).exists()) {
      print("File exists");
    } else {
      print("File don't exists");
    }
  }

  Future<String> get _localPath async {
    final directory = await getApplicationDocumentsDirectory();
    print(directory.path);
    return directory.path;
  }

  Future<File> get _localFile async {
    final path = await _localPath;
    return File('$path/$dataFile');
  }

  void appDetail() async {
    print("Getting app informations using 'device_apps' : ");
    List<Application> apps = await DeviceApps.getInstalledApplications(
      includeSystemApps: true,
      includeAppIcons: true,
      onlyAppsWithLaunchIntent: true,
    );
    print("Printing apps detail from appDetail() Funtion  apps : ");
    // for (int i = 0; i < apps.length; i++) print(apps[i]);

    print(apps);

    appsDetail = apps;

    for (int i = 0; i < apps.length; i++) {
      ApplicationWithIcon icon = apps[i] as ApplicationWithIcon;

      print(icon.icon.runtimeType);

      // print(apps[i]);
      _json.add({
        "totalApps": apps.length,
        "appName": apps[i].appName,
        "apkFilePath": apps[i].apkFilePath,
        "packageName": apps[i].packageName,
        "versionName": apps[i].versionName,
        "versionCode": apps[i].versionCode,
        "dataDir": apps[i].dataDir,
        "systemApp": apps[i].systemApp,
        "installTimeMillis": apps[i].installTimeMillis,
        "updateTimeMillis": apps[i].updateTimeMillis,
        "icon": icon.icon,

        // "category": apps[i].category
      });
    }

    print(_json);
  }

  void writeJsonfile() async {
    print("Writing json file : ");

    _filePath = await _localFile;

    print("json before encoding : ");
    print("$_json");

    jsonString = jsonEncode(_json);

    print("jsonString after encoding : ");

    print(jsonString);
    _filePath.writeAsString(
      jsonEncode(jsonString),
    );
  }

  Future<List<Object>> Apps() async {
    print("Reading Json file");

    _filePath = await _localFile;
    _fileExists = await _filePath.exists();
    print('0. File exists? $_fileExists');

    if (_fileExists) {
      try {
        String jsonString = await _filePath.readAsString();
        _json = jsonDecode(jsonString);
        print('printing json file after reading : ');
        print(_json);
        return _json;
      } catch (e) {
        // Print exception errors
        print('Tried reading _file error: $e');
        // If encountering an error, return null
      }
    } else {}
  }

  @override
  void initState() {
    super.initState();
    appDetail();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(title: Text('Reading and Writing data')),
        body: Column(
          children: <Widget>[
            IconButton(icon: Icon(Icons.ac_unit), onPressed: Apps),
            _json.length >= 1
                ? GridView.builder(
                    shrinkWrap: true,
                    physics: ScrollPhysics(),
                    scrollDirection: Axis.vertical,
                    itemCount: _json.length,
                    gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
                        crossAxisCount: 5, childAspectRatio: 2.0),
                    itemBuilder: (BuildContext context, int index) {
                      print("Checking");
                      print(_json[index]["icon"].runtimeType);
                      var icon = _json[index]["icon"];
                      return Column(
                        children: <Widget>[
                          Expanded(child: Text(_json[index]["appName"])),
                          Expanded(child: Image.memory(icon)),
                        ],
                      );
                    })
                : Text("No Data Found"),
          ],
        ));
  }
}

1,395

Author by

pyt

Updated on December 24, 2022

Comments

pyt over 1 year

I was using a flutter plugin named device_apps to get the application information installed in my android device.

It returns a List<Application> which porvides icon if I cast the Object from Application to ApplicationWithIcon.

But the icon it retuns is a Uint8 List type and i want to save it locally and use it later in Image.memory().

If i directly use it without saving locally then it works fine as Image.memory(app.icon).But When i saved the icon in a json file and then used it then it shows the error :

type 'List' is not a subtype of type 'Uint8List'

How can i save it locally and then use it ?

import 'dart:async';
import 'dart:convert';
import 'dart:ffi';
import 'dart:io';
import 'dart:typed_data';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
import 'package:device_apps/device_apps.dart';
import 'package:app_settings/app_settings.dart';
import 'package:flutter/services.dart' show rootBundle;

void main() {
  runApp(
    MaterialApp(
      title: 'Reading and Writing Files',
      home: MyApp(),
    ),
  );
}

const String dataFile = 'data1.json';

class MyApp extends StatefulWidget {
  @override
  _AppState createState() => _AppState();
}

class _AppState extends State<MyApp> {
  String data;

  File _filePath;
  bool _fileExists = false;
  String jsonString;

  List<dynamic> _json = [];
  List<dynamic> _jsonshow = [];

  List<Application> appsDetail;

  void checkFile() async {
    // chek if file exists
    String dir = (await getApplicationDocumentsDirectory()).path;
    String savePath = '$dir/$dataFile';

//for a directory: await Directory(savePath).exists();
    if (await File(savePath).exists()) {
      print("File exists");
    } else {
      print("File don't exists");
    }
  }

  Future<String> get _localPath async {
    final directory = await getApplicationDocumentsDirectory();
    print(directory.path);
    return directory.path;
  }

  Future<File> get _localFile async {
    final path = await _localPath;
    return File('$path/$dataFile');
  }

  void appDetail() async {
    print("Getting app informations using 'device_apps' : ");
    List<Application> apps = await DeviceApps.getInstalledApplications(
      includeSystemApps: true,
      includeAppIcons: true,
      onlyAppsWithLaunchIntent: true,
    );
    print("Printing apps detail from appDetail() Funtion  apps : ");
    // for (int i = 0; i < apps.length; i++) print(apps[i]);

    print(apps);

    appsDetail = apps;

    for (int i = 0; i < apps.length; i++) {
      ApplicationWithIcon icon = apps[i] as ApplicationWithIcon;

      print(icon.icon.runtimeType);

      // print(apps[i]);
      _json.add({
        "totalApps": apps.length,
        "appName": apps[i].appName,
        "apkFilePath": apps[i].apkFilePath,
        "packageName": apps[i].packageName,
        "versionName": apps[i].versionName,
        "versionCode": apps[i].versionCode,
        "dataDir": apps[i].dataDir,
        "systemApp": apps[i].systemApp,
        "installTimeMillis": apps[i].installTimeMillis,
        "updateTimeMillis": apps[i].updateTimeMillis,
        "icon": icon.icon,

        // "category": apps[i].category
      });
    }

    print(_json);
  }

  void writeJsonfile() async {
    print("Writing json file : ");

    _filePath = await _localFile;

    print("json before encoding : ");
    print("$_json");

    jsonString = jsonEncode(_json);

    print("jsonString after encoding : ");

    print(jsonString);
    _filePath.writeAsString(
      jsonEncode(jsonString),
    );
  }

  Future<List<Object>> Apps() async {
    print("Reading Json file");

    _filePath = await _localFile;
    _fileExists = await _filePath.exists();
    print('0. File exists? $_fileExists');

    if (_fileExists) {
      try {
        String jsonString = await _filePath.readAsString();
        _json = jsonDecode(jsonString);
        print('printing json file after reading : ');
        print(_json);
        return _json;
      } catch (e) {
        // Print exception errors
        print('Tried reading _file error: $e');
        // If encountering an error, return null
      }
    } else {}
  }

  @override
  void initState() {
    super.initState();
    appDetail();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(title: Text('Reading and Writing data')),
        body: Column(
          children: <Widget>[
            IconButton(icon: Icon(Icons.ac_unit), onPressed: Apps),
            _json.length >= 1
                ? GridView.builder(
                    shrinkWrap: true,
                    physics: ScrollPhysics(),
                    scrollDirection: Axis.vertical,
                    itemCount: _json.length,
                    gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
                        crossAxisCount: 5, childAspectRatio: 2.0),
                    itemBuilder: (BuildContext context, int index) {
                      return Column(
                        children: <Widget>[
                          Expanded(child: Text(_json[index]["appName"])),
                          Expanded(child: Image.memory(_json[index]["icon"])),
                        ],
                      );
                    })
                : Text("No Data Found"),
          ],
        ));
  }
}

Mehedi Hasan Shifat over 3 years

can you show me the error log?
pyt over 3 years

Only that message nothing else !
Mehedi Hasan Shifat over 3 years

can you show me the code?
Abion47 over 3 years

If you need help with your code, you need to show the code.
jamesdlin over 3 years

I can't seem to reproduce this. Do you have a minimal, complete example? The error you're getting doesn't make much sense to me, and the claimed fix makes even less sense. Also, are you getting the error when running your application from analysis?
pyt over 3 years

what you you mean "from analysis" ? i was testing it in my emulator.
pyt over 3 years

Did you test my code?