Static classes
Learn how to define and use static classes.
Static classes
A static class cannot be instantiated and may contain only static members. It is declared as static class Config { ... }.
Static classes are ideal for collecting helper and utility functions: Math, Convert, Console are examples. Because no instance can be created, new Config() is a compile error. Members must also be marked static.
When to use a static class?
If every member of a class is already static, marking the class itself static is recommended. It prevents accidental instantiation and signals intent.
For example, a StringHelper class that only has static methods like Capitalize and Truncate is a good candidate. If you need to hold instance state, a static class is wrong; use a normal class.
Exercise Configuration class
Define a static class Config. Add a public static string AppName = "Quiz"; field. In Main, print Config.AppName.
Show example solution
Add `static class Config { public static string AppName = "Quiz"; }`. In Main write `Console.WriteLine(Config.AppName);`.
Example solution:
using System;
static class Config
{
public static string AppName = "Quiz";
}
class Program
{
static void Main()
{
Console.WriteLine(Config.AppName);
}
}Test yourself
-
Match: static class properties
- static class
- cannot be instantiated
- new Config()
- compile error
- member
- must be static
- use case
- helper functions
-
Fill in the blank: static class declaration
static ____ { public static string AppName = "Quiz"; }Show answer
static class Config { public static string AppName = "Quiz"; } -
Which statement about static classes is FALSE?
- A static class cannot be instantiated.
- All members of a static class must be static.
- Math is a static class.
- A static class can have an instance constructor.
Show answer
A static class can have an instance constructor. — Correct (false statement). A static class cannot have an instance constructor; only a static constructor is allowed.