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How to implement Null object Pattern in C#?
The null object pattern helps us to write a clean code avoiding null checks where ever possible. Using the null object pattern, the callers do not have to care whether they have a null object or a real object. It is not possible to implement null object pattern in every scenario. Sometimes, it is likely to return a null reference and perform some null checks.
Example
static class Program{
static void Main(string[] args){
Console.ReadLine();
}
public static IShape GetMobileByName(string mobileName){
IShape mobile = NullShape.Instance;
switch (mobileName){
case "square":
mobile = new Square();
break;
case "rectangle":
mobile = new Rectangle();
break;
}
return mobile;
}
}
public interface IShape {
void Draw();
}
public class Square : IShape {
public void Draw() {
throw new NotImplementedException();
}
}
public class Rectangle : IShape {
public void Draw() {
throw new NotImplementedException();
}
}
public class NullShape : IShape {
private static NullShape _instance;
private NullShape(){ }
public static NullShape Instance {
get {
if (_instance == null)
return new NullShape();
return _instance;
}
}
public void Draw() {
}
}
Updated on: 25-Nov-2020
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