Deep copy and Shallow copy

Shallow Copy

• Shallow copy creates new object
• Then copy all non static fields to the new object
• System.Object.MemberwiseClone() method creates shallow copy of object

Deep Copy

• Deep copy creates new object
• Then copy all feilds to the new object
• Deep copy of an object can be created using Serialization
• Mark the target class as [Serializable]

 
References:

1. MemberWiseClone - (shallow copy)

Scenario: (C#.NET) There is an Employee class, which has 2 properties, ID & Name. There is an Employee class object E1. I want to create Shallow copy to E2 & Deep copy to E3. How?


 [Serializable]
    public  class Employee : ICloneable
    {
        private int id;
        private string name;

        public int ID
        {
            get { return id; }
            set { id = value; }
        }

        public string Name
        {
            get { return name; }
            set { name = value; }
        }

        public Employee ShallowCopy()
        {
            //shallow copy
            return (Employee)this.MemberwiseClone();
        }

        #region ICloneable Members

        public object Clone()
        {
            //deep copy
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            System.Runtime.Serialization.Formatters.Binary.BinaryFormatter bf = new System.Runtime.Serialization.Formatters.Binary.BinaryFormatter();
            bf.Serialize(ms, this);
            ms.Position = 0;
            object obj = bf.Deserialize(ms);
            ms.Close();
            return obj;
           
        }

        #endregion
    }

    class DeepShallowSample
    {

        public DeepShallowSample()
        {
            Employee e1 = new Employee();
            e1.ID = 162;
            e1.Name = "Nidhish";
            Console.WriteLine(e1.GetHashCode());
           
            //Shallow copy
            Employee e2 = e1.ShallowCopy();
            Console.WriteLine(e2.GetHashCode());

            //Deep copy
            Employee e3 = (Employee)e1.Clone();  
            Console.WriteLine(e3.GetHashCode());   

           
        }
       
     
    }