//here is the method in class A that populates its own entities
public ReadProximityEvents(String file)
{
    FileStream fs = File.OpenRead(file);
    reader = new BinaryReader(fs);

    int type = reader.ReadInt32();
    Console.WriteLine(type);

    for (int x = 0; x < type; x++)
    {
        entities.Add("");

        while (true)
        {
            char next = reader.ReadChar();

            if (next != '|')
            {
                entities[x] += next;
            }
            else
            {
                break;
            }
        }

        entities[x] = entities[x].Trim().ToLower();
        Console.WriteLine(entities[x]);

    //this method outputs:
    //3
   //pencil
    //smartboard
   //tabletc
    }
}

//here is class B that is instantiated with the entities obtained above
public class Parser
{
    List<String> entities = new List<String>();

    public Parser(List<String> entities)
    {
        this.entities = entities;
    }

    public bool validate()
    {
        for(int x = 0; x < entities.Count; x++)
        {
            Console.WriteLine(entities[x] + " " +  ("a pencil g smartboard tabletc ".IndexOf(entities[x])));

        //outputs
        //pencil -1
        //smartboard 11
       //tabletc -1
        }

        return true;
    }
}