In Java, an enum is a special data type that allows a variable to take on one of a predefined set of values. Enums are typically used to represent a fixed set of values that are related to each other in some way.
To define an enum in Java, you use the enum keyword followed by the name of the enum and a list of the possible values for that enum. For example:
enum DayOfWeek {
MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY
}
In the above example, DayOfWeek is an enum that represents the days of the week. The possible values for this enum are MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, and SUNDAY.
Enums can also have additional fields and methods, just like a regular Java class. For example:
enum DayOfWeek {
MONDAY(1), TUESDAY(2), WEDNESDAY(3), THURSDAY(4), FRIDAY(5), SATURDAY(6), SUNDAY(7);
private int value;
private DayOfWeek(int value) {
this.value = value;
}
public int getValue() {
return value;
}
}
In the above example, the DayOfWeek enum has an additional field value that stores the numerical value of each day of the week, and a method getValue() that returns the value of the enum for a given day.
Enums are useful in situations where you want to restrict the possible values of a variable to a predefined set of values. They can also make your code more readable and maintainable by using descriptive names instead of numeric values.
