File storage in Flutter - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is file storage in mobile apps?

File storage means saving data as files on the device's storage, like saving a photo or a note. It helps keep data even when the app is closed.

beginner

Which Flutter package is commonly used for file storage?

The path_provider package helps find device folders to save files, and dart:io is used to read/write files.

intermediate

What is the difference between temporary and persistent storage?

Temporary storage is for files that can be deleted anytime (like cache). Persistent storage keeps files safe until the user deletes them or uninstalls the app.

intermediate

How do you get the app's documents directory in Flutter?

Use getApplicationDocumentsDirectory() from path_provider. It returns a folder where you can save files that should persist.

intermediate

Why should you handle file operations asynchronously in Flutter?

File reading and writing can take time. Doing it asynchronously keeps the app smooth and responsive, avoiding freezes or delays.

Which Flutter package helps locate device directories for file storage?

A http

B path_provider

C flutter_local_notifications

D shared_preferences

The path_provider package provides paths to commonly used locations on the device file system.

What does getTemporaryDirectory() return?

A A folder for temporary files that can be deleted anytime

B A folder for files that persist forever

C The root folder of the device

D The app's assets folder

getTemporaryDirectory() returns a folder for temporary files that the system may delete when needed.

Which Dart library is used to read and write files?

A dart:convert

B dart:math

C dart:async

D dart:io

dart:io provides classes like File to read and write files on the device.

Why should file operations be done asynchronously in Flutter?

A To make the app run slower

B Because synchronous code is not allowed

C To avoid blocking the user interface

D To save battery

Asynchronous file operations keep the app responsive by not blocking the UI thread.

Where should you save user-generated files that need to persist?

A Application documents directory

B Temporary directory

C Cache directory

D Assets folder

The application documents directory is meant for files that should persist between app launches.

Explain how to save a text file in Flutter using file storage.

Think about how to find the folder, create a file, and write text to it without freezing the app.

Describe the difference between temporary and persistent storage and when to use each in a mobile app.

Consider what happens if the app closes or the device runs low on space.