Abstract method

1. ABSTRACT CLASS

2. ABSTRACT CLASS
Definition:
 The class is created for the purpose of providing common fields
and members to all subclasses then this type of class is called an
abstract class.
 While we are declaring a class if we used abstract keyword
that is abstract class.
 Abstract class is a collection of abstract members and non
abstract members.

3. ABSTRACT CLASS
• Syntax for Abstract class:
abstract class <class name>
{
//abstract Members;
or
//Non abstract members;
}
 We can use abstract key word for Properties , events & methods
,So an abstract class can contain abstract properties ,abstract
events and abstract methods

4. ABSTRACT CLASS
Abstract Method:
 Abstract members can contain only declaration part in abstract class
that means it will contain only skeleton of the member.
 The definition of abstract member (or) implementation of abstract
member should be in derived class.
 We should implement abstract members in derived class using
override keyword.
Syntax For Abstract method:
abstract <return type> <method name>();
Example:
abstract void display();

5. ABSTRACT CLASS
• Abstract class can not be instantiated, that means we can not
create object for abstract class.
• We have to access members using derived class object only.
Syntax for Abstract Property:
abstract <data type> <property name>
{
get;
set;
}

6. ABSTRACT CLASS
 We can not declare abstract class as a sealed class because
sealed class will not inherited to derived class.
 If we declare abstract class as a sealed class we can not
implement abstract members in derived class.
Example:
abstract sealed class Demo
{
}
o/p: Error

7. ABSTRACT CLASS
 We can not use private access modifier for abstract class as
well as abstract members.
 Because we can not access that abstract class members in
the derived class.
Example:
private abstract void display();
{
}
o/p: Error

8. ABSTRACT CLASS
• By default abstract members all are virtual .
• We can not use virtual key word for abstract members.
• Access modifier of a abstract member should be same in
the abstract class and derived class.
Ex:
public abstract void Demo
{
public void m1();
}
public class Demo1:Demo
{
public override void m1()
{;
}
}