How to implement database creation using the Room library in Android?

To create a database using the Room library in Android, you need to follow several steps:

1. Define entities — classes that will represent tables in the database. Each class field corresponds to a table column.

import androidx.room.Entity
import androidx.room.PrimaryKey

@Entity(tableName = "users")
data class User(
    @PrimaryKey(autoGenerate = true) val id: Int = 0,
    val name: String,
    val age: Int
)

2. Create DAO (Data Access Object) — an interface with methods for data access (insertion, update, deletion, queries).

import androidx.room.Dao
import androidx.room.Insert
import androidx.room.Query

@Dao
interface UserDao {
    @Insert
    suspend fun insertUser(user: User)

    @Query("SELECT * FROM users")
    suspend fun getAllUsers(): List<User>
}

3. Create a database class inheriting from RoomDatabase and declare entities and DAO in it.

import androidx.room.Database
import androidx.room.RoomDatabase

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

4. Initialize the database in the application using Room.databaseBuilder.

import androidx.room.Room

val db = Room.databaseBuilder(
    context.applicationContext,
    AppDatabase::class.java, "app-database"
).build()

val userDao = db.userDao()

Thus, Room will automatically generate the necessary code to work with SQLite, providing convenient and safe data access.