How to list files/folder from internal or SD card storage in Flutter App

In this example, we have shown to list all the files or folders from Internal or External (SD Card) storage. You can also add an extension filter to list files with specific path extension. This type of functionality is very important for a PDF viewer, image viewer, or audio player apps.

To list all the files or folders, you have to use flutter_file_manager, path, and path_provider_ex flutter package. Add the following lines in your pubspec.yaml file to add this package in your dependency.

dependencies:
  flutter:
    sdk: flutter
  path: ^1.6.4
  path_provider_ex: ^1.0.1
  flutter_file_manager: ^0.2.0

Add read / write permissions in your android/app/src/main/AndroidManifest.xml before <application> tag.

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

If you still get the Permission Denied error, add the following line on AndroidManifest.xml file.

<application
      android:requestLegacyExternalStorage="true"

Flutter dart code, see the explanation in the comment.

import 'dart:io';
import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_file_manager/flutter_file_manager.dart';
import 'package:path_provider_ex/path_provider_ex.dart';
//import package files

void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return  MaterialApp(
          home: MyFileList(), //call MyFile List 
    );
  }
}

//apply this class on home: attribute at MaterialApp()
class MyFileList extends StatefulWidget{
  @override
  State<StatefulWidget> createState() {
    return _MyFileList();
  }
}

class _MyFileList extends State<MyFileList>{
  var files;
 
  void getFiles() async { //asyn function to get list of files
      List<StorageInfo> storageInfo = await PathProviderEx.getStorageInfo();
      var root = storageInfo[0].rootDir; //storageInfo[1] for SD card, geting the root directory
      var fm = FileManager(root: Directory(root)); //
      files = await fm.filesTree( 
      //set fm.dirsTree() for directory/folder tree list
        excludedPaths: ["/storage/emulated/0/Android"],
        extensions: ["png", "pdf"] //optional, to filter files, remove to list all,
        //remove this if your are grabbing folder list
      );
      setState(() {}); //update the UI
  }

  @override
  void initState() {
    getFiles(); //call getFiles() function on initial state. 
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title:Text("File/Folder list from SD Card"),
        backgroundColor: Colors.redAccent
      ),
      body:files == null? Text("Searching Files"):
           ListView.builder(  //if file/folder list is grabbed, then show here
              itemCount: files?.length ?? 0,
              itemBuilder: (context, index) {
                    return Card(
                      child:ListTile(
                         title: Text(files[index].path.split('/').last),
                         leading: Icon(Icons.image),
                         trailing: Icon(Icons.delete, color: Colors.redAccent,),
                      )
                    );
              },
          )
    );
  }
}

Output:

In this way, you can list all the files or folders from Internal or External (SD card) storage and show in your app.