Abstraction (Java and C# Cross Reference Guide)

Java supports marking a full class as abstract as well as class members. A subclass must either implement the abstract members or you must declare the subclass abstract (which delays the implementation to it's subclass).

public abstract class Dog {
  abstract void Bark();
}

 Java Abstraction (abstract)

C# supports abstract class members and abstract classes using the abstract modifier.

An abstract class is a class with one or more abstract members and you cannot instantiate an abstract class. However, you can have additional implemented methods and properties.

An abstract member is either a method (implicitly virtual), property, indexer, or event in an abstract class. You can add abstract members ONLY to abstract classes using the abstract keyword. Then you override it in a descendant class with Override.

abstract public class Cyborg : System.Object

{

  abstract public void Speak(string pMessage);

}

public class Series600 : Cyborg

{

  public override void Speak(string pMessage)  

  {

    MessageBox.Show(pMessage);  

  }

}

 C# Abstraction (abstract, override)