1. Introduction<\/h2>\n
Data management is an essential element in modern application development. The database for storing user information or the state of the application is becoming increasingly important. In Android applications, the use of databases is essential for effectively managing user data. In this course, we will cover how to store data in a database using Kotlin.<\/p>\n<\/section>\n There are various databases that can be used in Android, among which the most commonly used are as follows:<\/p>\n This course will focus on SQLite and Room.<\/p>\n<\/section>\n SQLite is a simple and efficient way to store data locally. It allows for quick access to requested data in component-based Android applications. To use the SQLite database, the following key steps must be followed.<\/p>\n SQLiteOpenHelper is a class for creating and managing database versions. It helps manage the database.<\/p>\n Below is a simple implementation example of SQLiteOpenHelper:<\/p>\n Now, let’s learn how to insert, read, update, and delete data in the database.<\/p>\n Room is a library that provides a simpler and more flexible way to access databases. It reduces the amount of database-related code and helps to use the database more safely. Room consists of three main components:<\/p>\n Defining an Entity in Room is akin to designing a table. Below is a simple example of a User Entity:<\/p>\n DAO defines methods to perform CRUD (Create, Read, Update, Delete) operations on the database:<\/p>\n The RoomDatabase class allows for the instantiation of DAO and the creation of the database:<\/p>\n Using the Room database, here’s how you can insert, retrieve, update, and delete data:<\/p>\n In this course, we learned how to utilize databases in Android apps using Kotlin. We understood the advantages and disadvantages of both SQLite and Room, and learned how to store and manage data in an application through concrete implementation examples. Now, we hope you can use these techniques to effectively manage user data and enhance the functionality of your app.<\/p>\n<\/section>\n<\/article>\n <\/body><\/p>\n","protected":false},"excerpt":{"rendered":"2. Types of Databases<\/h2>\n
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3. SQLite Database<\/h2>\n
3.1. SQLiteOpenHelper Class<\/h3>\n
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\n class MyDatabaseHelper(context: Context) : SQLiteOpenHelper(context, DATABASE_NAME, null, DATABASE_VERSION) {\n override fun onCreate(db: SQLiteDatabase) {\n val createTableSQL = \"CREATE TABLE ${TABLE_NAME} (\" +\n \"${COLUMN_ID} INTEGER PRIMARY KEY AUTOINCREMENT, \" +\n \"${COLUMN_NAME} TEXT)\"\n db.execSQL(createTableSQL)\n }\n \n override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {\n db.execSQL(\"DROP TABLE IF EXISTS $TABLE_NAME\")\n onCreate(db)\n }\n }\n <\/code>\n <\/pre>\n3.2. Inserting, Retrieving, Updating, and Deleting Data<\/h3>\n
Inserting Data<\/h4>\n
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\n fun insertData(name: String) {\n val db = this.writableDatabase\n val values = ContentValues().apply {\n put(COLUMN_NAME, name)\n }\n db.insert(TABLE_NAME, null, values)\n db.close()\n }\n <\/code>\n <\/pre>\nRetrieving Data<\/h4>\n
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\n fun getData(): ListUpdating Data<\/h4>\n
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\n fun updateData(id: Int, newName: String) {\n val db = this.writableDatabase\n val values = ContentValues().apply {\n put(COLUMN_NAME, newName)\n }\n db.update(TABLE_NAME, values, \"$COLUMN_ID = ?\", arrayOf(id.toString()))\n db.close()\n }\n <\/code>\n <\/pre>\nDeleting Data<\/h4>\n
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\n fun deleteData(id: Int) {\n val db = this.writableDatabase\n db.delete(TABLE_NAME, \"$COLUMN_ID = ?\", arrayOf(id.toString()))\n db.close()\n }\n <\/code>\n <\/pre>\n<\/section>\n4. Room Database<\/h2>\n
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4.1. Defining Entity Classes<\/h3>\n
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\n @Entity(tableName = \"user_table\")\n data class User(\n @PrimaryKey(autoGenerate = true) val id: Int = 0,\n @ColumnInfo(name = \"name\") val name: String\n )\n <\/code>\n <\/pre>\n4.2. Defining DAO Interfaces<\/h3>\n
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\n @Dao\n interface UserDao {\n @Insert\n suspend fun insert(user: User)\n \n @Query(\"SELECT * FROM user_table\")\n suspend fun getAllUsers(): List4.3. Defining RoomDatabase Class<\/h3>\n
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\n @Database(entities = [User::class], version = 1)\n abstract class UserDatabase : RoomDatabase() {\n abstract fun userDao(): UserDao\n \n companion object {\n @Volatile\n private var INSTANCE: UserDatabase? = null\n\n fun getDatabase(context: Context): UserDatabase {\n return INSTANCE ?: synchronized(this) {\n val instance = Room.databaseBuilder(\n context.applicationContext,\n UserDatabase::class.java,\n \"user_database\"\n ).build()\n INSTANCE = instance\n instance\n }\n }\n }\n }\n <\/code>\n <\/pre>\n4.4. Manipulating Data<\/h3>\n
Inserting Data<\/h4>\n
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\n private fun insertUser(user: User) {\n CoroutineScope(Dispatchers.IO).launch {\n val db = UserDatabase.getDatabase(context)\n db.userDao().insert(user)\n }\n }\n <\/code>\n <\/pre>\nRetrieving Data<\/h4>\n
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\n private fun getAllUsers() {\n CoroutineScope(Dispatchers.IO).launch {\n val db = UserDatabase.getDatabase(context)\n val users = db.userDao().getAllUsers()\n }\n }\n <\/code>\n <\/pre>\nUpdating Data<\/h4>\n
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\n private fun updateUser(user: User) {\n CoroutineScope(Dispatchers.IO).launch {\n val db = UserDatabase.getDatabase(context)\n db.userDao().update(user)\n }\n }\n <\/code>\n <\/pre>\nDeleting Data<\/h4>\n
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\n private fun deleteUser(user: User) {\n CoroutineScope(Dispatchers.IO).launch {\n val db = UserDatabase.getDatabase(context)\n db.userDao().delete(user)\n }\n }\n <\/code>\n <\/pre>\n<\/section>\n5. Conclusion<\/h2>\n