Fun with EnumSet

Do you know EnumSet? No? Then you should take the time to look at this sample code. EnumSet allows writing of really eloquent Java source code. Run the following code and watch its result printed on the screen. Then check the below source code to find out how it works. The source code particulary makes use of (at least) the following features introduced in Java 5:

• enum keyword

The enum keyword allows to define enumerations.

• enum custom methods

Enumerations can have custom methods.

• enum toString()

Enumerations provide an automatic implementation of toString() that returns the name of the enum value.

• EnumSet.range()

This method returns a set of enumeration values created from a range of enumeration values.

• EnumSet.allOf()

This method returns a set of enumeraton values that contain all values of the specified enumeration.

• EnumSet.clone()

Create a complete copy of a set of enumeration values.

• EnumSet.removeAll()

Subtract a set of enumeration values from another one.

• EnumSet.size()

Gets the number of enumeration values in the set.

• EnumSet iteration

You can iterate over a set of enumeration values using the for-each statement of Java 5.

• String.format(), including automatic calling of .toString()

String.format() provides a cool way to format messages, and it automaticaly calls .toString() internally.

 import java.util.EnumSet;
 
 public final class EnumSetSample {
 
 	private enum Weekday {
 		MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY;
 
 		public static final EnumSet<Weekday> WORKDAYS = EnumSet.range(MONDAY, FRIDAY);
 
 		public final boolean isWorkday() {
 			return WORKDAYS.contains(this);
 		}
 
 		public static final EnumSet<Weekday> THE_WHOLE_WEEK = EnumSet.allOf(Weekday.class);
 	}
 
 	public static final void main(final String... argumgents) {
 		System.out.println("Work Schedule:");
 
 		for (final Weekday weekday : Weekday.THE_WHOLE_WEEK)
 			System.out.println(String.format("%d. On %s you " + (weekday.isWorkday() ? "have to work" : "can relax") + ".", weekday.ordinal() + 1, weekday));
 
 		System.out.println("Do I have to work the whole week?");
 
 		System.out.println(Weekday.WORKDAYS.containsAll(Weekday.THE_WHOLE_WEEK) ? "Yes, unfortunately." : "Certainly not.");
 
 		final EnumSet<Weekday> weekend = Weekday.THE_WHOLE_WEEK.clone();
 		weekend.removeAll(Weekday.WORKDAYS);
 
 		System.out.println(String.format("The weekend is %d days long.", weekend.size()));
 
 	}
 }