Create a custom .NET exception

1. Create a class that derives from System.Exception class. As a convention, end the class name with Exception suffix. All .NET exceptions end with,  exception suffix. If you don’t do so, you won’t get a compiler error, but you will be deviating from the guidelines for creating custom exceptions.

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   public class UserAlreadyLoggedInException: Exception{}
   

2. Provide a public constructor, that takes in a string parameter. This constructor simply passes the string parameter, to the base exception class constructor.

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   public UserAlreadyLoggedInException(string message)
    :base(message){}
   

3. Using InnerExceptions, you can also track back the original exception. If you want to provide this capability for your custom exception class, then overload the constructor as shown below.

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   public UserAlreadyLoggedInException(string message, Exception innerException)
    :base(message, innerException){}
   

4. If you want your Exception class object to work across application domains, then the object must be serializable. To make your exception class serializable mark it with Serializable attribute and provide a constructor that invokes the base Exception class constructor that takes in SerializationInfo and StreamingContext objects as parameters.

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   [Serializable]
   public class UserAlreadyLoggedInException: Exception
   {
    public UserAlreadyLoggedInException(string message): base(message)
    {
    }
   
    public UserAlreadyLoggedInException(string message, Exception innerException)
        :base(message, innerException)
    {
    }
       
    public UserAlreadyLoggedInException(SerializationInfo info, StreamingContext context)
        :base(info, context)
    {
    }
   }
   

Reference: kudvenkat’s youtube video

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