RoomDB.java

package com.example.trip_packer.Database;

import android.content.Context;

import androidx.room.Database;
import androidx.room.Room;
import androidx.room.RoomDatabase;

import com.example.trip_packer.Dao.ItemsDao;
import com.example.trip_packer.Models.Items;

@Database(entities = Items.class,version  =1,exportSchema = false)

public abstract class RoomDB extends RoomDatabase {

    private static RoomDB database;
    private static String DATABASE_NAME ="MyDb";

    public synchronized static RoomDB getInstance(Context context)
    {
      if(database==null)
      {
          database= Room.databaseBuilder(context.getApplicationContext(),RoomDB.class,DATABASE_NAME).allowMainThreadQueries().fallbackToDestructiveMigration().build();
      }
      return database;
    }
    public abstract ItemsDao mainDao();

}