When you need to represent a fixed set of related constants in your Java programs, enums provide a clear and powerful solution. An enum (short for "enumeration") is a special Java type used to define collections of named constants, such as the days of the week, directions, or the suits in a deck of cards. Unlike traditional constants—such as public static final int MONDAY = 1;—enums group related values under a single type, making your code more readable, type-safe, and less error-prone. Enums help you avoid mistakes like assigning an invalid value or mixing up unrelated constants, and they can even include methods and fields for more advanced scenarios. Overall, enums are a modern alternative to groups of constants, providing structure and clarity to your code.

In the example above, you declare an enum called Day that lists all seven days of the week as named constants. This enum is defined inside the DayEnumExample class. To use an enum value, you simply refer to it as Day.MONDAY. In the main method, you assign Day.MONDAY to a variable named today, then print it out. This approach ensures that only valid days can be assigned to variables of type Day, preventing errors like assigning an invalid integer or misspelled string. Enum types give you compile-time type safety, making your code both safer and easier to understand.