Dart FileSystemEntityType

last modified April 4, 2025

The FileSystemEntityType class in Dart represents types of file system entities. It’s used to identify whether a path refers to a file, directory, or link.

This enum-like class is part of Dart’s dart:io library. It’s commonly used with file system operations to determine entity types before performing specific actions.

Basic Definition

FileSystemEntityType is an abstract class with constant values representing different file system entity types. It cannot be instantiated.

The class provides four possible values: FILE, DIRECTORY, LINK, and NOT_FOUND. These help identify what kind of entity a path points to in the file system.

Checking File Type

This example shows how to check if a path points to a regular file.

main.dart

import ‘dart:io’;

void main() async { var file = File(’example.txt’); await file.writeAsString(‘Hello, Dart!’);

var type = await FileSystemEntity.type(’example.txt’); print(type == FileSystemEntityType.file); // true

await file.delete(); }

We create a file, check its type using FileSystemEntity.type(), then delete it. The method returns a FileSystemEntityType value we can compare against constants.

$ dart main.dart true

Checking Directory Type

This example demonstrates checking if a path points to a directory.

main.dart

import ‘dart:io’;

void main() async { var dir = Directory(’test_dir’); await dir.create();

var type = await FileSystemEntity.type(’test_dir’); print(type == FileSystemEntityType.directory); // true

await dir.delete(); }

We create a directory, verify its type using FileSystemEntityType.directory, then clean up. This is useful before performing directory-specific operations.

$ dart main.dart true

Checking Symbolic Link Type

This example shows how to identify a symbolic link using FileSystemEntityType.

main.dart

import ‘dart:io’;

void main() async { var file = File(’target.txt’); await file.writeAsString(‘Link target’);

var link = Link(’link.txt’); await link.create(’target.txt’);

var type = await FileSystemEntity.type(’link.txt’); print(type == FileSystemEntityType.link); // true

await link.delete(); await file.delete(); }

We create a file and a symbolic link to it. The type check confirms the link’s nature. Always clean up temporary files after such operations.

$ dart main.dart true

Handling Non-Existent Paths

This example demonstrates how FileSystemEntityType handles non-existent paths.

main.dart

import ‘dart:io’;

void main() async { var type = await FileSystemEntity.type(’nonexistent.txt’); print(type == FileSystemEntityType.notFound); // true

if (type == FileSystemEntityType.notFound) { print(‘Path does not exist’); } }

When checking a non-existent path, FileSystemEntityType returns NOT_FOUND. This helps distinguish between different types of “file not found” scenarios.

$ dart main.dart true Path does not exist

Directory Listing with Type Checking

This example shows how to list directory contents with type information.

main.dart

import ‘dart:io’;

void main() async { var dir = Directory(’test’); await dir.create();

await File(’${dir.path}/file.txt’).create(); await Directory(’${dir.path}/subdir’).create();

var entities = dir.list(); await for (var entity in entities) { var type = await FileSystemEntity.type(entity.path); print(’${entity.path}: ${type.toString().split(’.’).last}’); }

await dir.delete(recursive: true); }

We create a directory with a file and subdirectory, then list them with types. The type() method helps categorize each entity during directory traversal.

$ dart main.dart test/file.txt: file test/subdir: directory

Best Practices

• Async handling: Always await FileSystemEntity.type() calls

• Error checking: Handle NOT_FOUND cases appropriately

• Type safety: Use == operator for type comparisons

• Cleanup: Delete temporary files after testing

Source

Dart FileSystemEntityType Documentation

This tutorial covered Dart’s FileSystemEntityType class with practical examples showing how to identify different file system entities in Dart applications.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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