Java Enums

Java Enums

In Java, an enum (enumeration) is a special type that defines a set of constants. Enums are used to represent fixed sets of values, such as days of the week, months, status codes, etc. Enum constants are implicitly public, static, and final. They are typically used when a variable can only take one of a few predefined values. Here's an overview of Java enums:

Declaring Enums:

• Enums are declared using the enum keyword followed by the enum name.
• Enum constants are defined within curly braces {}.

Example of declaring an enum:

        public enum Day {
            MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY
        }
     

Using Enums:

• Enum constants are accessed using the enum type name followed by the constant name.
• Enums can have additional properties and methods like any other Java class.

Example of using enums:

        public class Main {
            public static void main(String[] args) {
                Day today = Day.MONDAY;
                System.out.println("Today is " + today); // Output: Today is MONDAY
                
                // Enums can be used in switch statements
                switch (today) {
                    case MONDAY:
                        System.out.println("It's the first day of the week");
                        break;
                    case FRIDAY:
                        System.out.println("It's almost the weekend");
                        break;
                    default:
                        System.out.println("Just another day");
                }
            }
        }
     

Enum Constructors and Methods:

• Enums can have constructors, fields, and methods like regular Java classes.
• Each enum constant can have its own values and behavior.

Example of enums with constructors and methods:

        public enum Day {
            MONDAY("Monday"), TUESDAY("Tuesday"), WEDNESDAY("Wednesday"),
            THURSDAY("Thursday"), FRIDAY("Friday"), SATURDAY("Saturday"), SUNDAY("Sunday");
            
            private final String displayName;
            
            private Day(String displayName) {
                this.displayName = displayName;
            }
            
            public String getDisplayName() {
                return displayName;
            }
        }
        
        public class Main {
            public static void main(String[] args) {
                Day today = Day.MONDAY;
                System.out.println("Today is " + today.getDisplayName()); // Output: Today is Monday
            }
        }
     

Benefits of Enums:

• Type Safety: Enums provide type safety by restricting variables to a predefined set of values.
• Readability: Enums improve code readability by providing descriptive names for constant values.
• Compile-Time Checks: Since enum constants are known at compile time, they provide compile-time checks for their usage.