Java enum

Java enum

• 1.
  Java Enum Sujit Kumar ZenolocityLLC Copyright @ 2012 - 2024
• 2.
  Enums • An enumtype is a type whose fields consist of a fixed set of constants. • The names of an enum type's fields are in uppercase letters. • Example: public enum Day { SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY }
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  When to useEnums • Use an Enum any time you need to represent a fixed set of constants. • Examples: Months of Year Days of Week Entries in a Menu Colors Directions of Compass
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  Enums (contd…) • Enumsare like classes, they can have fields (state) and methods (behavior). • All enums implicitly extend java.lang.Enum. Since Java does not support multiple inheritance, an enum cannot extend anything else. • Typesafe => compile-time error checking. • You can use a switch on enum values.
• 5.
  Enums (contd…) • toString()returns the enum value as a String — can be overridden. • values() method returns an array of all the enum values. • Can be used in collections as objects more efficiently than int values — no boxing/unboxing required! • Implement the Comparable and Serializable interfaces.
• 6.
  High Performance Setand Map implementations for Enums • EnumSet All of the members of an EnumSet must be of the same enum type. Supports iteration over a range of enum types. • EnumMap Almost the same speed as an array. If you want to map an enum to a value, use an EnumMap instead of an array. EnumMap's implementation uses an array and for that reason has slightly better performance than HashMaps.