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Sealed Class in C#

Last Updated : 16 Sep, 2025
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Sealed classes are used to restrict the users from inheriting the class. A class can be sealed by using the sealed keyword. The keyword tells the compiler that the class is sealed and therefore, cannot be extended. No class can be derived from a sealed class.

Syntax:

sealed class class_name
{
// data members
// methods
.
.
.
}

A method can also be sealed and in that case, the method cannot be overridden. However, a method can be sealed in the classes in which they have been inherited. If you want to declare a method as sealed, then it has to be declared as virtual in its base class.

Example 1: Create a Sealed Class that can be used in Geeks Class

C# 
using System;

// Sealed class
sealed class SealedClass {
	// Calling Function
	public int Add(int a, int b){
		return a + b;
	}
}

class Geeks{
	static void Main(string[] args)
	{
		// Creating an object of Sealed Class
		SealedClass slc = new SealedClass();

		// Performing Addition operation
		int total = slc.Add(6, 4);
		Console.WriteLine("Total = " + total.ToString());
	}
}

Output
Total = 10

Example 2: When we try to inherit a class from a sealed class, an error will be produced stating that "It cannot be derived from a Sealed class"

C# 
using System;

class Bird
{
}

// Creating a sealed class
sealed class Test : Bird
{
}

// Inheriting the Sealed Class
class Example : Test
{
}

class Geeks
{
  	// Main Method
	static void Main()
	{
    }
}

Output:

./Solution.cs(13,7): error CS0509: `Example': cannot derive from sealed type `Test'
./Solution.cs(8,14): (Location of the symbol related to previous error)
Compilation failed: 1 error(s), 0 warnings

Example 3: Program to define Sealed Class Method

C# 
using System;

class Printer {
	// Displaying dimension printing
	public virtual void show()
	{
		Console.WriteLine("Display dimension : 6*6");
	}
	
	public virtual void print()
	{
		Console.WriteLine("Printer printing....\n");
	}
}

// Inheriting class
class LaserJet : Printer 
{
	// Sealed Display Function for Dimension printing
	sealed override public void show()
	{
		Console.WriteLine("Display dimension : 12*12");
	}

	// Function to override Print() function
	override public void print()
	{
		Console.WriteLine("Laserjet printer printing....\n");
	}
}

// Officejet class cannot override show function as it is sealed in LaserJet class.
class Officejet : LaserJet 
{
	
	override public void print()
	{
		Console.WriteLine("Officejet printer printing....");
	}
}

class Geeks 
{
	// Main Method
	static void Main(string[] args)
	{
		Printer p = new Printer();
		p.show();
		p.print();

		Printer ls = new LaserJet();
		ls.show();
		ls.print();

		Printer of = new Officejet();
		of.show();
		of.print();
	}
}

Output
Display dimension : 6*6
Printer printing....

Display dimension : 12*12
Laserjet printer printing....

Display dimension : 12*12
Officejet printer printing....

Important Points

  • A sealed class is used to stop a class from being inherited. We cannot derive or extend any class from it.
  • The sealed method is implemented so that no other class can overthrow it and implement its method.
  • The main purpose of the sealed class is to withdraw the inheritance attribute from the user so that they can’t attain a class from a sealed class.
  • Sealed classes are used best when we have a class with static members.

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Akanksha_Rai
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