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what is sealed class?

Posted By :Narayanan     Posted Date :September 07, 2011    Points :40   Category :.NET Framework 
restrict inheritance feature of OOP.sealed class can no t inherited.

You can also find related Interview Question to what is sealed class?  below: 

What is the WebPartManager sealed class? What is its purpose?

  
The WebPartManager sealed class is responsible for managing everything occurring on a WebPart page, such as the WebParts (controls), events, and misc. functionality that will occur in WebPartZones. For example, the WebPartManager is responsible for the functionality that is provided when you are working with moving a WebPart from WebPartZone to WebPartZone. It is known as the "the central class of the Web Part Control Set." (More...)

What is the WebPartManager sealed class? What is its purpose?

  
The WebPartManager sealed class is responsible for managing everything occurring on a WebPart page, such as the WebParts (controls), events, and misc. functionality that will occur in WebPartZones. For example, the WebPartManager is responsible for the functionality that is provided when you are working with moving a WebPart from WebPartZone to WebPartZone. It is known as the "the central class of the Web Part Control Set." *** Side Question: I got asked how many WebPartManager controls should be on a page. In order to have WebParts on a page there has to be just one WebPartManager control to manage all the WebParts on the page. (More...)

All about Sealed Class

  
Sealed classes are used to restrict the inheritance feature of object oriented programming.

· Once class is defined as sealed class, this class cannot be inherited so we can't derive class.

· Keywords: C# - Sealed , VB.NET - NotInheritable

· If you have ever noticed, struct are sealed. You cannot derive a class from a struct.

· A sealed class cannot be used as a base class. For this reason, it cannot also be an abstract class.

· The best usage of sealed classes is when you have a class with static members.

· Example - The Pens and Brushes classes of the System.Drawing namespace. The Pens class represent the pens for standard colors. This class has only static members. Pens.Blue represents a pen with blue color. Similarly, the Brushes class represents standard brushes. The Brushes.Blue represents a brush with blue color. (More...)

What is the WebPartManager sealed class? What is its purpose?

  

The WebPartManager sealed class is responsible for managing everything occurring on a WebPart page, such as the WebParts (controls), events, and misc. functionality that will occur in WebPartZones. For example, the WebPartManager is responsible for the functionality that is provided when you are working with moving a WebPart from WebPartZone to WebPartZone. It is known as the "the central class of the Web Part Control Set." (More...)

Is it possible to modify an abstract class with sealed Modifier?

  
no, Because the two modifier have opposite meanings. (More...)

What is mean by Sealed Class?

  
The sealed modifier is used to prevent derivation from a class. A compile-time error occurs if a sealed class is specified as the base class of another class. (A sealed class cannot also be an abstract class). (More...)

What is sealed class

  
When sealed modifier applied to a class,it prevents other classes from inheriting from it. (More...)

What is the WebPartManager sealed class? Why do we add this on WebPart Page?

  
The WebPartManager sealed class is responsible for managing everything occurring on a WebPart page, such as the WebParts (controls), events, and misc. functionality that will occur in WebPartZones. For example, the WebPartManager is responsible for the functionality that is provided when you are working with moving a WebPart from WebPartZone to WebPartZone. It is known as the "the central class of the Web Part Control Set." (More...)

What is the WebPartManager sealed class?What is its purpose?

  
The WebPartManager sealed class is responsible for managing everything occurring on a WebPart page, such as the WebParts (controls), events, and misc. functionality that will occur in WebPartZones. For example, the WebPartManager is responsible for the functionality that is provided when you are working with moving a WebPart from WebPartZone to WebPartZone. It is known as the "the central class of the Web Part Control Set." (More...)

What is the WebPartManager sealed class? What is its purpose?

  
The WebPartManager sealed class is responsible for managing everything occurring on a WebPart page, such as the WebParts (controls), events, and misc. functionality that will occur in WebPartZones. For example, the WebPartManager is responsible for the functionality that is provided when you are working with moving a WebPart from WebPartZone to WebPartZone. It is known as the "the central class of the Web Part Control Set." (More...)

What is the difference between a Struct and a Class?

  
The struct type is suitable for representing lightweight objects such as Point, Rectangle, and Color. Although it is possible to represent a point as a class, a struct is more efficient in some scenarios. For example, if you declare an array of 1000 Point objects, you will allocate additional memory for referencing each object. In this case, the struct is less expensive.

When you create a struct object using the new operator, it gets created and the appropriate constructor is called. Unlike classes, structs can be instantiated without using the new operator. If you do not use new, the fields will remain unassigned and the object cannot be used until all of the fields are initialized.

It is an error to declare a default (parameterless) constructor for a struct. A default constructor is always provided to initialize the struct members to their default values.

It is an error to initialize an instance field in a struct.

There is no inheritance for structs as there is for classes. A struct cannot inherit from another struct or class, and it cannot be the base of a class. Structs, however, inherit from the base class Object. A struct can implement interfaces, and it does that exactly as classes do.

A struct is a value type, while a class is a reference type. (More...)

Can we call a base class method without creating instance?

  
Its possible If its a static method.

Its possible by inheriting from that class also.

Its possible from derived classes using base keyword. (More...)

What is Private Constructor? and it's use? Can you create instance of a class which has Private Constructor?

  
When a class declares only private instance constructors, it is not possible for classes outside the program to derive from the class or to directly create instances of it. (Except Nested classes)
Make a constructor private if:

1) You want it to be available only to the class itself. For example, you might have a special constructor used only in the implementation of your class' Clone method.

2) You do not want instances of your component to be created. For example, you may have a class containing nothing but Shared utility functions, and no instance data. Creating instances of the class would waste memory. (More...)

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