Android Data Storage | SharedPreferences, SQLite, Room & File Storage

SharedPreferences

SharedPreferences is used to store small amounts of simple data in key-value pairs.

What it stores
🔸 Strings, integers, booleans, floats
🔸 User settings and preferences

Common use cases
🔸 Login state (isLoggedIn)
🔸 Theme mode (dark/light)
🔸 App language or basic configuration

Advantages
🔸 Very easy to use
🔸 Fast read/write operations
🔸 No database structure required

Limitations
🔸 Not suitable for large or complex data
🔸 No relational data support

SQLite

SQLite is a lightweight relational database built directly into Android.

Key characteristics
🔸 Uses SQL queries
🔸 Stores structured data in tables
🔸 Supports CRUD operations

Common use cases
🔸 Offline-first apps
🔸 Large datasets
🔸 Apps requiring relational data

Advantages
🔸 Powerful and flexible
🔸 Handles large volumes of data
🔸 Supports joins and indexing

Limitations
🔸 Requires writing SQL queries
🔸 More boilerplate code
🔸 Error-prone without proper handling

Room Database

Room is an abstraction layer built on top of SQLite, part of Android Jetpack.

Core components
🔸 Entity – Represents a table
🔸 DAO (Data Access Object) – Defines database operations
🔸 Database – Holds the database configuration

Why use Room
🔸 Compile-time query validation
🔸 Less boilerplate than SQLite
🔸 Works seamlessly with LiveData and ViewModel

Best use cases
🔸 Modern Android apps
🔸 Clean architecture (MVVM)
🔸 Apps requiring reliable local databases

File Storage

File Storage is used to store raw files such as images, videos, PDFs, or text files.

Types of file storage
🔸 Internal Storage – Private to the app
🔸 External Storage – Accessible by user and other apps (with permission)

Common use cases
🔸 Saving images or videos
🔸 Downloaded documents
🔸 Cache files

Advantages
🔸 Suitable for large files
🔸 Simple file-based access
🔸 Persistent storage

Limitations
🔸 Requires permission handling (external storage)
🔸 Not suitable for structured data