- Basic Features
- Enum is a sealed class defining constant sets with compile-time instantiation
- Constants must be in uppercase with underscores
- Enum constants are public, static and final by default
- Values() method returns array of enum constants in declaration order
- Implementation Details
- Enums cannot have public constructors, only private ones
- Fields should be private and provide getter methods
- Multiple constructors allowed with arguments
- Enums implicitly implement Serializable and Comparable
- Advanced Features
- Can implement abstract methods for member behavior
- Can be used for singleton pattern with single-element enum
- Supports zero-instance enum with empty constant list
- Can be used as bounded type parameter in generics
- Usage and Comparison
- Can be compared directly using ==
- Values can be accessed through values() method
- Can be converted to String using name() or toString()
- Can implement polymorphism through interfaces