What methods can be used to implement the application's ability to work offline?

To implement offline functionality in an Android application, the following methods can be used:

1. Local data storage:

   • Using SQLite or Room to save data on the device.
   • SharedPreferences for storing small settings.

2. Data caching:

   • Caching server responses using libraries like Retrofit with OkHttp.

3. Data synchronization:

   • Synchronize local changes with the server when the connection is restored.

4. Handling network absence:

   • Monitor network status via ConnectivityManager and adapt the UI accordingly.

5. Using WorkManager:

   • Schedule synchronization tasks that run when network is available.

Example of using Room for local storage:

@Entity
data class User(
    @PrimaryKey val id: Int,
    val name: String
)

@Dao
interface UserDao {
    @Query("SELECT * FROM user")
    fun getAll(): List<User>

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    fun insertAll(vararg users: User)
}

@Database(entities = [User::class], version = 1)
abstract class AppDatabase : RoomDatabase() {
    abstract fun userDao(): UserDao
}

Thus, the application can work with local data, providing functionality without an internet connection.