C#

Stream s = File.OpenWrite("<filepath>");

foreach (Student student in studentList)
{
    xmlSerializer.Serialize(s, student);
}

s.Flush();
s.Close();
</filepath>

public class StudentCollection : List<student>
{
    //
}
public static List<student> DeSerialize()
{
    // DeSerialize here
}

public new void Add(Student student)
{
    // Do validation and duplication checks here
    base.Add(student);
    Serialize(this);
}
public static void Serialize(List<student> studentCollection)
{
    // Serialize here;
}

CodingYoshi wrote:

deserialize all students from file into a collection, add new students to collection and reserialize

public abstract class ImageBase
{
  public int X { get; set; }
  public int Y { get; set; }
  public int Width { get; set; }
  public int Height { get; set; }
  // More properties

  public virtual ImageBase Save()
  {
  }

  public virtual void Load(/* some form of stream */ item)
  {
    // Rehydrate the object from the stream.
  }
}