Inheritance
Download as PPTX, PDF0 likes1,092 views
This document discusses inheritance in .NET. It explains that inheritance allows new classes to reuse and extend the behavior of existing classes. It provides examples of base and derived classes, and inheritance hierarchies. It also discusses the benefits of inheritance such as code reuse and applying methods to different data types. Additionally, it covers constructor flow in inheritance and access modifiers like private, protected, internal and their access levels.
Inheritance
- 3. Part I ◦ Inheritance: When, Why, How ◦ Inheritance in .NET Framework ◦ Inheritance Demo Example Part II ◦ Constructor Flow in Inheritance Part III ◦ Access Modifiers: private, public, protected, internal, protected internal www.dotnetvideotutorial.com
- 5. Inheritance enables you to create new classes that reuse, extend, and modify the behavior that is defined in other classes. Base class class MyBase { private int field1; public void fun1() { } } Derived class class MyDerived : MyBase { private int field2; public void fun2() { } } Object of MyDerived obj field1 www.dotnetvideotutorial.com field2
- 8. Employee Generalized Base Class EmpNo Name Department Designation NetSalary Specialized Derived Class OffRollEmployee OnRollEmployee BasicSalary PerHourRate HRA WorkedHours GrossSalary PF www.dotnetvideotutorial.com
- 15. inheritance hierarchy represents an "is-a" relationship and not a "has-a" relationship. can reuse code from the base classes. need to apply the same class and methods to different data types. The class hierarchy is reasonably shallow, and other developers are not likely to add many more levels. want to make global changes to derived classes by changing a base class. www.dotnetvideotutorial.com
- 16. Every class directly of indirectly derives from object class Multiple class Inheritance is not allowed. Multilevel is obvious! Multiple interface implementation is possible. www.dotnetvideotutorial.com
- 17. Part I ◦ Inheritance: When, Why, How ◦ Shadowing ◦ Inheritance Demo Example Part II ◦ Constructor Flow in Inheritance Part III ◦ Access Modifiers: private, public, protected, internal, protected internal www.dotnetvideotutorial.com
- 18. Constructor never get derived Always base class constructor executes first. www.dotnetvideotutorial.com
- 19. class MyBase { protected int no1, no2; class MyDerived : MyBase { private int no3; public MyBase() { } public MyDerived() : base() { } public MyBase(int n1,int n2) { this.no1 = n1; this.no2 = n2; } public MyDerived(int n1,int n2,int n3) : base(n1,n2) { this.no3 = n3; } } } Client Code MyDerived obj1 = new MyDerived(); MyDerived obj2 = new MyDerived(10, 20, 30); no1 no2 no3
- 21. Part I ◦ Inheritance: When, Why, How ◦ Shadowing ◦ Inheritance Demo Example Part II ◦ Constructor Flow in Inheritance Part III ◦ Access Modifiers: private, public, protected, internal, protected internal www.dotnetvideotutorial.com
- 22. Access modifiers are keywords used to specify the declared accessibility of a member or a type public • Access is not restricted. private • Access is limited to the containing type. protected internal protected internal • Access is limited to the containing class or types derived from the containing class. • Access is limited to the current assembly. • Access is limited to the current assembly or types derived from the containing class. www.dotnetvideotutorial.com
- 23. Assembly - 1 Assembly - 2 class A { private int no1; protected int no2; internal int no3; protected internal int no4; public int no5; } class B : A { } class C { } class D : A { } class E { } What is accessible where? no1 •A no2 •A, B, D no3 •A, B, C no4 •A, B, C, D no5 •A, B, C, D, E www.dotnetvideotutorial.com