package User; import android.arch.persistence.room.Database; import android.arch.persistence.room.Room; import android.arch.persistence.room.RoomDatabase; import android.content.Context; @Database(entities = {User.class}, version = 1) public abstract class UserRoomDatabase extends RoomDatabase { private static UserRoomDatabase INSTANCE; public abstract UserDao userDao(); public static UserRoomDatabase getDatabase(final Context context) { if(INSTANCE == null) { synchronized (UserRoomDatabase.class) { if(INSTANCE == null) { INSTANCE = Room.databaseBuilder(context.getApplicationContext(), UserRoomDatabase.class, "users") .build(); } } } return INSTANCE; } }