An `enum` is a *special* class that represents a group of constants.

**Enum keyword** is used to create an `enum`. The constants declared inside are separated by a comma and should be in upper case.


## Example
An `enum` can be declared inside a class or outside a class. In the example below, we are declaring it inside a class:

class MyClass { 
  enum color {  // declaring an enum using the enum keyword 
    // defining enum constants using the enum keyword
    RED,
    GREEN,
    BLUE
  }

  public static void main(String[] args) { 
    
    color x = color.GREEN; // storing
    System.out.println(x); 
  } 
}

## Properties of enum

1. Similar to a class, an `enum` can have objects and methods. The only difference is that `enum` constants are `public`, `static` and `final` by default. Since it is `final`, we can’t create child enums
2.  It cannot extend other classes since it already extends the `java.lang.Enum` class.
3. It can implement interfaces.
4. The `enum` objects cannot be created explicitly and hence the `enum` constructor cannot be invoked directly.
5. It can only contain concrete methods and no abstract methods.
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## Where to use enum?
`enum` is used for values that are not going to change e.g. names of days, colors in a rainbow, number of cards in a deck etc. 

`enum` is commonly used in switch statements and below is an example of it:

class MyClass { 
  enum color {  // declaring an enum using the enum keyword 
    // defining enum constants using the enum keyword
    RED,
    GREEN,
    BLUE
  }

  public static void main(String[] args) { 

    color x = color.GREEN; // storing value 
    switch(x) {
      case RED:
        System.out.println("x has RED color");
        break;
      case GREEN:
        System.out.println("x has GREEN color");
        break;
      case BLUE:
        System.out.println("x has BLUE color");
        break;
    }
  } 
}

What are enums in Java?

Example

Properties of enum

Where to use enum?