What's the use of “enum” in Java? [duplicate]

Answer 1

You use an enum instead of a class if the class should have a fixed enumerable number of instances.

Examples:

• DayOfWeek  = 7 instances → enum
• CardSuit    = 4 instances → enum
• Singleton  = 1 instance   → enum
  
  
• Product      = variable number of instances → class
• User            = variable number of instances → class
• Date            = variable number of instances → class