Java Enums

An enum type is a type whose fields consist of a fixed set of constants.
Common examples include compass directions (values of NORTH, SOUTH, EAST, and WEST) and the days of the week.
They were added from JDK 1.5 onwards.
Until then we would denote constants as
```
public static constant int monday = 1;
```
You then had to write code to convert strings like "Monday" to the number 1, then compare to the variable monday.

A simple enum looks as follows:

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

You should use enum types any time you need to represent a fixed set of constants. This avoids the hassle of converting a variable to String or integer values.

Here is some code that shows you how to use the Day enum defined above:

public class EnumTest
    {
    Day day;

    public EnumTest(Day day)
    {
        this.day = day;
    }

    public void tellItLikeItIs()
    {
        switch (day) 
        {
        case MONDAY:
            System.out.println("Mondays are bad.");
            break;

        case FRIDAY:
            System.out.println("Fridays are better.");
            break;

        case SATURDAY:
        case SUNDAY:
            System.out.println("Weekends are best.");
            break;

        default:
            System.out.println("Midweek days are so-so.");
            break;

        }
    }

    public static void main(String[] args)
    {
        EnumTest firstDay = new EnumTest(Day.MONDAY);
        firstDay.tellItLikeItIs();

        EnumTest thirdDay = new EnumTest(Day.WEDNESDAY);
        thirdDay.tellItLikeItIs();

        EnumTest fifthDay = new EnumTest(Day.FRIDAY);
        fifthDay.tellItLikeItIs();

        EnumTest sixthDay = new EnumTest(Day.SATURDAY);
        sixthDay.tellItLikeItIs();

        EnumTest seventhDay = new EnumTest(Day.SUNDAY);
        seventhDay.tellItLikeItIs();
    }
    }

The output is:

Mondays are bad.
    Midweek days are so-so.
    Fridays are better.
    Weekends are best.
    Weekends are best.

Source: http://download.oracle.com/javase/tutorial/java/javaOO/enum.html

Download the CloudCoverage.java and CloudTest.java files for a more in-depth example.