AppDatabase.java

@Database(entities = Movie.class, version = 1, exportSchema = false)
public abstract class AppDatabase extends RoomDatabase {

    public static final String DATABASE_DB = "database.db";
    private static AppDatabase appDatabase;

    public static AppDatabase getInstance(Context context) {
        if (appDatabase == null) {
            appDatabase = Room.databaseBuilder(context, AppDatabase.class, DATABASE_DB).allowMainThreadQueries().build();
        }
        return appDatabase;
    }

    public abstract MovieDao getMovieDao();
}