AppDatabase.java

@Database(entities = {BorrowModel.class}, version = 1)
public abstract class AppDatabase extends RoomDatabase {

    private static AppDatabase INSTANCE;

    public static AppDatabase getDatabase(Context context) {
        if (INSTANCE == null) {
            INSTANCE =
                    Room.databaseBuilder(context.getApplicationContext(), AppDatabase.class, "borrow_db")
                            .build();
        }
        return INSTANCE;
    }

    public abstract BorrowModelDao itemAndPersonModel();

}