This document discusses the evolution of data persistence in Android using SQLite, including SQLiteOpenHelper, third party ORM libraries like ORMLite and Sugar ORM, and the Room persistence library. It covers how to set up SQLiteOpenHelper to perform CRUD operations, how third party libraries simplify data access, and how Room provides an abstraction layer over SQLite with additional functionality like type converters and query capabilities. Examples of entity, database, and DAO classes are shown for each approach.

2. A EVOLUÇÃO DA
PERSISTÊNCIA DE
DADOS (COM SQLITE)
NO ANDROID
http://bit.ly/evolucao-persistencia

3. RODRIGO CASTRO
Desenvolvedor Android @ Concrete
Analista de Sistemas pela UFMS/CPCX.
De Coxim/MS para o mundo!
http://castrors.github.io
rodrigo.castro@concrete.com.br
@rodrigocastro_o

4. SUMÁRIO
Conteúdo
• SQLiteOpenHelper
• Libs de terceiros
• Room API

5. SQLITE OPEN HELPER
https://developer.android.com/training/basics/data-st
orage/databases.html

6. SETUP
public class LoanDbHelper extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
static final String DATABASE_NAME = "openhelper.db";
private static final String TAG = "LoanDbHelper";
private LoanDbHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

7. ON CREATE E ON UPGRADE
@Override
public void onCreate(SQLiteDatabase db) {
final String SQL_CREATE_BOOK_TABLE = "CREATE TABLE " +
BookEntry.TABLE_NAME + " (" +
BookEntry._ID + " INTEGER PRIMARY KEY," +
BookEntry.COLUMN_TITLE + " TEXT NOT NULL);";
db.execSQL(SQL_CREATE_BOOK_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
if (oldVersion != newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + BookEntry.TABLE_NAME);
onCreate(db);
}
}

8. INSERT
public void addBook(Book book) {
SQLiteDatabase db = getWritableDatabase();
db.beginTransaction();
try {
ContentValues values = new ContentValues();
values.put(BookEntry._ID, book.getId());
values.put(BookEntry.COLUMN_TITLE, book.getTitle());
db.insertOrThrow(BookEntry.TABLE_NAME, null, values);
db.setTransactionSuccessful();
} catch (Exception e) {
Log.d(TAG, "Error while trying to add book to database");
} finally {
db.endTransaction();
}
}

9. SELECT
SQLiteDatabase db = getReadableDatabase();
Cursor cursor = db.rawQuery("SELECT * FROM book", null);
try {
if (cursor.moveToFirst()) {
do {
int bookId = cursor.getInt(cursor.getColumnIndex(BookEntry._ID));
String title = cursor.getString(cursor.getColumnIndex(BookEntry.COLUMN_TITLE));
Book book = new Book(bookId, title);
books.add(book);
} while (cursor.moveToNext());
}
} catch (Exception e) {
Log.d(TAG, "Error while trying to get books from database");
} finally {
if (cursor != null && !cursor.isClosed()) {
cursor.close();
}
}

10. BIBLIOTECAS ORM DE
TERCEIROS
https://android-arsenal.com/tag/69?sort=created
https://www.sitepoint.com/5-best-android-orms/

11. ORMLITE
@DatabaseTable(tableName = "user")
public class User {
@DatabaseField(id = true)
private String username;
@DatabaseField
private String password;
public User() {
// ORMLite needs a no-arg constructor
}
public User(String username, String password) {
this.username = username;
this.password = password;
}
// Implementing getter and setter methods
}

12. SURGAR ORM
public class User extends SugarRecord<User> {
String username;
String password;
int age;
@Ignore
String bio; //this will be ignored by SugarORM
public User() { }
public User(String username, String password,int age){
this.username = username;
this.password = password;
this.age = age;
}
}

13. ACTIVE ANDROID
@Table(name = "User")
public class User extends Model {
@Column(name = "username")
public String username;
@Column(name = "password")
public String password;
public User() {
super();
}
public User(String username,String password) {
super();
this.username = username;
this.password = password;
}
}

14. GREEN DAO
@Entity(indexes = {
@Index(value = "username DESC", unique = true)
})
public class User {
@Id
private Long id;
@NotNull
private String username;
private String password;
//getters and setters
}

15. ANDROID DEV SUMMIT 2015 (44:02 - 44:53)

16. TÍTULO
SLIDES

17. GOOGLE I/O 2017 (2:26 - 2:35)

18. ROOM API
https://developer.android.com/topic/libraries/architec
ture/room.html

19. SETUP
compile 'android.arch.persistence.room:runtime:1.0.0-alpha3'
annotationProcessor 'android.arch.persistence.room:compiler:1.0.0-alpha3'

20. ENTITY
@Entity
public class User {
@PrimaryKey
String id;
String name;
String lastName;
int age;
}

21. DATABASE
@Database(entities = {User.class}, version = 1)
public abstract class AppDatabase extends RoomDatabase {
private static AppDatabase instance;
public abstract UserDao userModel();
public static AppDatabase getDatabase(Context context) {
if (instance == null) {
instance = Room.databaseBuilder(context,
AppDatabase.class, "database-name").build();
}
return instance;
}
public static void destroyInstance() {
instance = null;
}
}

22. DAO
@Dao
public interface UserDao {
@Query("select * from user")
List<User> loadAllUsers();
@Query("select * from user where id = :id")
User loadUserById(int id);
@Query("select * from user where name = :firstName and lastName = :lastName")
List<User> findByNameAndLastName(String firstName, String lastName);
}

23. DAO
@Dao
public interface UserDao {
@Insert(onConflict = IGNORE)
void insertOrReplaceUsers(User... users);
@Delete
void deleteUsers(User user1, User user2);
}

24. DAO
@Dao
public interface UserDao {
@Query("select name from user")
List<String> loadAllUserNames();
@Query("select age, name from user")
List<Pojo> loadAllUsersWithAgeAndName();
class Pojo {
int age;
String name;
}
}

25. ERRORS
SQLiteOpenHelper - Runtime Exception
Caused by: android.database.sqlite.SQLiteException: no such table: users
(code 1): , while compiling: SELECT * FROM users
Room API - Compile Error
Error:(31, 18) error: There is a problem with the query: [SQLITE_ERROR]
SQL error or missing database (no such table: users)

26. TYPE CONVERTER
public class DateConverter {
@TypeConverter
public static Date toDate(Long timestamp) {
return timestamp == null ? null : new Date(timestamp);
}
@TypeConverter
public static Long toTimestamp(Date date) {
return date == null ? null : date.getTime();
}
}
@TypeConverters(DateConverter.class)

27. EMBEDDED
@Entity
public class User {
@PrimaryKey
String id;
String name;
String lastName;
int age;
Location location;
}
Error:(29, 21) error: Cannot figure out how to save this field into database.
You can consider adding a type converter for it.

28. EMBEDDED
@Entity
public class User {
@PrimaryKey
String id;
String name;
String lastName;
int age;
@Embedded
Location location;
}

29. SMART JOIN
@Query("SELECT Loan.id, Book.title, User.name, Loan.startTime, Loan.endTime From Loan " +
"INNER JOIN Book ON Loan.book_id = Book.id " +
"INNER JOIN User ON Loan.user_id = User.id ")
List<LoanWithUserAndBook> findAllWithUserAndBook();
@Query("SELECT startTime, name From Loan, User " +
"WHERE Loan.user_id = User.id ")
List<StartTimeWithUsername> findLoanStartTimeWithUsername();
class StartTimeWithUsername {
Date startTime;
String name;
}

30. MAIS ALGUMAS FEATURES
INDEX
MIGRATIONS
TESTABILITY

31. LINKS INTERESSANTES
https://github.com/castrors/PersistenceTalk
https://developer.android.com/topic/libraries/architecture/index.html
https://codelabs.developers.google.com/codelabs/android-persistence/index.html
https://codelabs.developers.google.com/codelabs/android-lifecycles/index.html
https://www.youtube.com/watch?v=MfHsPGQ6bgE
https://www.youtube.com/watch?v=FrteWKKVyzI

32. OBRIGADO!

33. Centro
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231 - 29º andar
(21) 2240-2030
Cidade Monções
Av. Nações Unidas,
11.541 - 3º andar
(11) 4119-0449
Savassi
Av. Getúlio Vargas, 671
Sala 800 - 8º andar
(31) 3360-8900
www.concrete.com.br