The purpose of an abstract class is to provide some heritable behaviors while also defining methods which must be implemented by sub-classes.
A class
with no abstract methods that was made abstract
purely to prevent instantiation should be converted to a concrete
class
(i.e. remove the abstract
keyword) with a protected
constructor.
A class
with only abstract
methods and no inheritable behavior should be converted to an interface
.
Noncompliant code example
public abstract class Animal //Noncompliant; should be an interface
{
abstract void Move();
abstract void Feed();
}
public abstract class Color //Noncompliant; should be concrete with a protected constructor
{
private int red = 0;
private int green = 0;
private int blue = 0;
public int GetRed()
{
return red;
}
}
Compliant solution
public interface Animal
{
void Move();
void Feed();
}
public class Color
{
private int red = 0;
private int green = 0;
private int blue = 0;
protected Color()
{}
public int GetRed()
{
return red;
}
}
public abstract class Lamp
{
private bool switchLamp = false;
public abstract void Glow();
public void FlipSwitch()
{
switchLamp = !switchLamp;
if (switchLamp)
{
Glow();
}
}
}