Android Jetpack: Room persistence library
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The document provides a comprehensive overview of the Android Jetpack Room Persistence Library, detailing its advantages such as abstraction over SQLite, compile-time checking for SQL statements, and easier testing and migration. It outlines the components involved, such as entities, DAOs, and Room database setup, alongside code examples for implementation. Additionally, it offers various resources for further learning and migration strategies from SQLite to Room.
Android Jetpack: Room persistence library
- 2. When start new android app … - Database: - Native SQLite - ORM wrapper on SQLite: DBFlow - Different database engines: Realm.
- 3. When start new android app … - Running a jobs: - AlarmManager + Broadcast Receiver - Firebase JobDispatcher - JobScheduler - GCMNetworkManager -
- 5. When start new android app … - Control data Slow and update latest data on UI. - Loading data: - Loading data from network. - Loading data from on-device database. - Loading data from multiple sources.
- 9. ViewModel
- 10. Live Data
- 17. Room Components
- 18. Entity public class Word { private String mWord; public Word(String word) {this.mWord = word;} public String getWord(){return this.mWord;} }
- 19. Entity @Entity(tableName = "word_table") public class Word { @PrimaryKey @NonNull @ColumnInfo(name = "word") private String mWord; public Word(String word) {this.mWord = word;} public String getWord(){return this.mWord;} }
- 24. DAO @Dao public interface WordDao { @Insert void insert(Word word); @Query("DELETE FROM word_table") void deleteAll(); @Query("SELECT * from word_table ORDER BY word ASC") LiveData<List<Word>> getAllWords(); }
- 25. DAO -Use annotation for simple actions such as insert/delete/update @Dao public interface WordDao { @Insert void insert(Word word); }
- 26. DAO -Write custom query. @Dao public interface WordDao { @Query("DELETE FROM word_table") void deleteAll(); @Query("SELECT * from word_table ORDER BY word ASC") LiveData<List<Word>> getAllWords(); }
- 29. DAO -Return LiveData data. @Dao public interface WordDao { @Query("SELECT * from word_table ORDER BY word ASC") LiveData<List<Word>> getAllWords(); }
- 30. Room Database -Abstraction over SQLiteHelper. @Database(entities = {Word.class}, version = 1) public abstract class WordRoomDatabase extends RoomDatabase { public abstract WordDao wordDao(); private static volatile WordRoomDatabase INSTANCE; static WordRoomDatabase getDatabase(final Context context) { if (INSTANCE == null) { synchronized (WordRoomDatabase.class) { if (INSTANCE == null) { // Create database here INSTANCE = Room.databaseBuilder(context.getApplicationContext(), WordRoomDatabase.class, "word_database") .addCallback(sRoomDatabaseCallback) .build(); } } } return INSTANCE; } }
- 31. Room Database
- 34. WorkSlow
- 35. 7 steps to to Room https://medium.com/androiddevelopers/7-steps-to-room-27a5fe5f99b2
- 36. Step 1: Add dependencies dependencies { // Room components implementation "android.arch.persistence.room:runtime:$rootProject.roomVersion" annotationProcessor "android.arch.persistence.room:compiler:$rootProject.roomVersion" androidTestImplementation "android.arch.persistence.room:testing:$rootProject.roomVersion" // Lifecycle components implementation "android.arch.lifecycle:extensions:$rootProject.archLifecycleVersion" annotationProcessor "android.arch.lifecycle:compiler:$rootProject.archLifecycleVersion" } build.gradle (module app)
- 37. Step 2: Update model to entity @Entity(tableName = "word_table") public class Word { @PrimaryKey @NonNull @ColumnInfo(name = "word") private String mWord; public Word(String word) {this.mWord = word;} public String getWord(){return this.mWord;} }
- 38. Step 3: Create DAO @Dao public interface WordDao { @Insert void insert(Word word); }
- 39. Step 3: Create DAO @Dao public interface WordDao { @Insert void insert(Word word); @Query("DELETE FROM word_table") void deleteAll(); @Query("SELECT * from word_table ORDER BY word ASC") LiveData<List<Word>> getAllWords(); }
- 40. Step 4: Create Database @Database(entities = {Word.class}, version = 1) public abstract class WordRoomDatabase extends RoomDatabase { }
- 41. Step 4: Create Database @Database(entities = {Word.class}, version = 1) public abstract class WordRoomDatabase extends RoomDatabase { public abstract WordDao wordDao(); }
- 42. Step 4: Create Database @Database(entities = {Word.class}, version = 1) public abstract class WordRoomDatabase extends RoomDatabase { public abstract WordDao wordDao(); private static volatile WordRoomDatabase INSTANCE; static WordRoomDatabase getDatabase(final Context context) { if (INSTANCE == null) { synchronized (WordRoomDatabase.class) { if (INSTANCE == null) { // Create database here INSTANCE = Room.databaseBuilder(context.getApplicationContext(), WordRoomDatabase.class, "word_database") .addCallback(sRoomDatabaseCallback) .build(); } } } return INSTANCE; } }
- 43. Step 5: Update Repository public class WordRepository { private WordDao mWordDao; private LiveData<List<Word>> mAllWords; }
- 44. Step 5: Update Repository public class WordRepository { private WordDao mWordDao; private LiveData<List<Word>> mAllWords; public WordRepository(Application application) { WordRoomDatabase db = WordRoomDatabase.getDatabase(application); mWordDao = db.wordDao(); mAllWords = mWordDao.getAllWords(); } public LiveData<List<Word>> getAllWords() { return mAllWords; } public void insert(Word word) { new insertAsyncTask(mWordDao).execute(word); } }
- 45. Step 6: Testing DAO @RunWith(AndroidJUnit4.class) public class WordDaoTest { private WordDao mWordDao; private WordRoomDatabase mDb; @Before public void createDb() { Context context = InstrumentationRegistry.getTargetContext(); mDb = Room.inMemoryDatabaseBuilder(context, WordRoomDatabase.class) // Allowing main thread queries, just for testing. .allowMainThreadQueries() .build(); mWordDao = mDb.wordDao(); } @After public void closeDb() { mDb.close(); } }
- 46. Step 6: Testing DAO @RunWith(AndroidJUnit4.class) public class WordDaoTest { private WordDao mWordDao; private WordRoomDatabase mDb; @Before public void createDb() { Context context = InstrumentationRegistry.getTargetContext(); mDb = Room.inMemoryDatabaseBuilder(context, WordRoomDatabase.class) // Allowing main thread queries, just for testing. .allowMainThreadQueries() .build(); mWordDao = mDb.wordDao(); } @After public void closeDb() { mDb.close(); } @Test public void insertAndGetWord() throws Exception { Word word = new Word("word"); mWordDao.insert(word); List<Word> allWords = LiveDataTestUtil.getValue (mWordDao.getAlphabetizedWords()); assertEquals(allWords.get(0).getWord(), word.getWord()); } }
- 47. Step 7: Clean up - Remove unused classes replaced by Room. (i.e: any class extends SQLiteHelper) - More complex project: - https://medium.com/androiddevelopers/incrementally-migrate-from-sqlite-to-room-66c2f655b377
- 53. Codelab - https://codelabs.developers.google.com/codelabs/android-lifecycles/#1 - https://codelabs.developers.google.com/codelabs/android-persistence/#0 - https://codelabs.developers.google.com/codelabs/android-room-with-a-view/#0 - https://codelabs.developers.google.com/codelabs/android-paging/#0
- 54. Q&A