Migrating the Room database, with only a new table added

One line answer

1. Write SQL that creates the new table in AppDatabase.java
2. Call the add-migration in DB initialization

The code

	// @Database...
	public abstract class AppDatabase extends RoomDatabase {
	public static final String DB_NAME = "Nhviewer";
	// public abstract ComicBookmarkDao comicBookmarkDao();
	// ...
	public static final Migration MIGRATION_1_2 = new Migration(1, 2) {
	@Override
	public void migrate(SupportSQLiteDatabase database) {
	// create comic bookmark table
	database.execSQL("CREATE TABLE IF NOT EXISTS `ComicBookmark` (`page` INTEGER NOT NULL, `id` INTEGER NOT NULL, `dateOfCreate` TEXT, PRIMARY KEY(`id`, `page`))");
	}
	};
	}

view raw AppDatabase.java hosted with ❤ by GitHub

	// ...
	private static AppDatabase appDatabase;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
	// ...
	appDatabase = Room.databaseBuilder(getApplicationContext(),
	AppDatabase.class, AppDatabase.DB_NAME)
	.addMigrations(AppDatabase.MIGRATION_1_2).build();
	}
	// ...

view raw MainActivity.java hosted with ❤ by GitHub

The problem

In my comic app project (NHViewer), I wanted to add a "bookmark" function to show the last seen page for each comic. 

So I need to create a new table for the Room database while keeping the original tables and data in the device. 

After some searching, I wrote the above code according to the AppDatabase's schema. 

Coda

During my searching, the Room database migration seems improved in the version 2.2.0 (androidx.room:room-*:2.2.0)
This note did not cover that part though 🙁

References

• Room cannot verify the data integrity
• SQLite_ERROR no such table
• Migrating Room databases | Android Developers