METHOD HIDING /SHADOWING

METHOD HIDING /SHADOWING

            Method hiding is also known as method shadowing type of polymorphism which deals with the concept.

“Method hiding is a process of re-implementation the parent class method in child class by changing its behavior while keep the same name and signature”.

Whereas the parent class need not to declare as virtual but still the child class has to declared with ‘new’ keyword like this. Not use of override.

Suppose if I have parent class and its method

public class Parentclass

polymorphism method hiding

{

  public void Test()

  {

     Statements;

   }

 }

public class Childclass: Parentclas

{

  public new void Test()

  {

     New Statements;

   }

 }

Here we use new keyword to shadowing but it can be possible without using new keyword, but the compiler raise a warning to you. We use to this keyword to make sure that the parent method also active otherwise without using the new keyword child class method hide the parent’s method and make it not active, if we doesn’t use new then in future it may be chance to forget that the parent also have a same name and signature method, and it can leads to our program fail.

Difference between method overriding and method hiding

            We have two approaches to re-implementing a parent class method under child class method which are.

1.    Method overriding ‘

2.    Method hiding/shadowing

Here the detail of these differences.

METHOD OVERRIDING        -       In this case the parent’s method must be  virtual to re-implement under child class.        -       The child’s method must be overridden to change the behavior.         -       Method can re-implement with the permission of parent class that is need to  declare ‘virtual’.        -       Due to permission the overridden member cannot considered as a pure child member.        -       The overridden member/method can be accessible to the parent instance. Because it built with parent permission and not a pure child class method.

METHOD HIDING/SHADOWING        -       In this case the parent’s method needs not to virtual to re-implement under child class. We can re-implement the normal method.        -       The child’s method must be declared with new keyword change the behavior.        -       Method can re-implement without the permission of parent class.        -       The method creates in the child as using new keyword considered as a pure child class member.        -       The parent reference can’t access the hiding method, because it purely a child method and pure member can’t e accessible for the parent

After re-implementing the parent classes under child class how I call the parent class

After re-implementing the parent classes under child class how I call the parent class?

            Yes! After re-implementing a parent class under child class we are still able to call the parent class by using two approaches.

1.    By creating the parent instance in the target class we can call the parent method like.

Parent p=new Parent ( );

2.    By using the base class keyword we can also calls the parent method form child class. But from static block we can’t use the base keyword to call. Like this.

base. Method();   // from non-static block

so what we do to overcome this problem, hence we need to create a new method in child class to has to make interface for the parent class like int the child class we can create a method and use like this.

Public void ParentMethod()

{

 base. Method();  //parent method name will place

            }

By using this process now we are able to call the parent class method after re-implementing by using child class instance from a static block and non-static block.