Tag: getInstance

Code to create a Room database in correspondence with the @Entity and @DAO entries.

Create an abstract class to outline the creation of your table
@Database(entities = {ContactEntry.class}, version = 1, exportSchema = false) // Add @Database annotation and declare class(es) containing @Entity
@TypeConverters(DateConverter.class) // See the @TypeConverters post: https://an.aldezu.com/archives/454 - not in use in this example but included for context
public abstract class AppDatabase extends RoomDatabase { // Extend RoomDatabase

    private static final String LOG_TAG = AppDatabase.class.getSimpleName();
    private static final Object LOCK = new Object();
    private static final String DATABASE_NAME = "contacts"; // Define database name
    private static AppDatabase sInstance;

    public static AppDatabase getInstance(Context context) {
        if (sInstance == null) { // This will only ever generate ONE instance of the AppDatabase (Singleton pattern)
            synchronized (LOCK) {
                Log.d(LOG_TAG, "Creating new database instance");
                sInstance = Room.databaseBuilder(context.getApplicationContext(), // Requires current context, the database class and database name
                        AppDatabase.class, AppDatabase.DATABASE_NAME)
                        .build();
            }
        }
        Log.d(LOG_TAG, "Getting the database instance");
        return sInstance; // Will return new instance if null, old instance if not
    }

    public abstract ContactDao contactDao(); // Create an instance of the DAO for this database

}

To interact with the table you will need a @DAO. To define the table you will need to use @Entity.