5.2 Encapsulation

File Location

1. Right click on your solution

2. Go to Add > New Project and select Class Library

3. Name it Encapsulation

Discussion

Encapsulation, in the context of C#, refers to an object's ability to hide data and behaviors that are not necessary to its user. Encapsulation enables a group of properties, methods and other members to be considered a single unit or object. (techopedia.com)

Encapsulation, in object oriented programming, prevents access to implementation details.

We learned about access modifiers in Part 3 of the modules. Encapsulation is basically the implementation of those access modifiers. Making elements of the program public, private, protected, internal, and protected internal.

Keyword	Applicable To	Meaning
public	Class, Member	No restrictions
protected	Member	Access limited to the class and derived class
private	Member	Access limited to the class
internal	Class, Member	Access limited to the current assembly
protected internal	Member	Access limited to the current assembly and derived types

For example, the public access modifier allows access to any code, but the private access modifier restricts access to only members of a type. Other access modifiers restrict access in the range somewhere between public and private. While you can use any of the access modifiers on type members, the only two access modifiers you can use on types are public and internal.

You can read more on this topic here.

Here is a bank example of why encapsulation could be useful.

 class BankAccountPublic
    {
//      Access at all levels
        public decimal GetAmount()
        {
            return 1000.00m;
        }
    }

Note: The GetAmount() function is available to all classes

 public class BankAccountPrivate
    {
        //Customary to put an _ before private fields.
        private string _name;
        private int _accountNumber;

        public string CustomerName
        {
            get { return _name; }
            set { _name = value; }
        }
    }

Note ApplyLateCharges() and CalculateInterest() are available to BankAccountProtected class and derived classes (BankAccountReopenedClosedAccount) because of the protected modifier.

 public class BankAccountProtected
    {
//      Available to current and derived classes
        public void CloseAccount()
        {
            ApplyLateCharges();
            CalculateInterest();
        }
//      Available to current and derived classes
        protected virtual void ApplyLateCharges()
        {
            Console.WriteLine("Apply Late Charges ran.");
        }

        protected virtual void CalculateInterest()
        {
            Console.WriteLine("Calculate Interest ran.");
        }
    }

 public class BankAccountReopenClosedAccount : BankAccountProtected
    {
        public void SettleDebt()
        {
            ApplyLateCharges();
            CalculateInterest();
        }
    }

Next: Getters and Setters