Sealed Class in C#

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

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"

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

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.