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Groovy example source code file (chameneos.java)

This example Groovy source code file (chameneos.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

blue, colour, colour, colours, creature, creature, faded, illegalargumentexception, interruptedexception, interruptedexception, meetingplace, meetingplace, red, yellow

The Groovy chameneos.java source code

/* The Computer Language Shootout
   http://shootout.alioth.debian.org/

   contributed by Keenan Tims
   modified by Michael Barker
*/


public class chameneos {

	private MeetingPlace mp;

	public static final Colour[] COLOURS = { Colour.BLUE, Colour.RED, Colour.YELLOW, Colour.BLUE };

	private Creature[] creatures = new Creature[COLOURS.length];

	public enum Colour {
		RED, BLUE, YELLOW, FADED
	}

	public class Creature extends Thread {

		private MeetingPlace mp;
		private Colour colour;
		private int met = 0;
		private Colour other;
		
		public Creature(Colour c, MeetingPlace mp) {
			this.colour = c;
			this.mp = mp;
		}

		public void run() {
			try {
				while (colour != Colour.FADED) {
					mp.meet(this);
					if (other == Colour.FADED)
						colour = Colour.FADED;
					else {
						met++;
						colour = complement(other);
					}					
				}
			} catch (InterruptedException e) {
				// Let the thread exit.
			}
		}
		
		private Colour complement(Colour other) {
			if (colour == other)
				return colour;
			switch (colour) {
			case BLUE:
				return other == Colour.RED ? Colour.YELLOW : Colour.RED;
			case RED:
				return other == Colour.BLUE ? Colour.YELLOW : Colour.BLUE;
			case YELLOW:
				return other == Colour.BLUE ? Colour.RED : Colour.BLUE;
			default:
				return colour;
			}
		}

		public int getCreaturesMet() {
			return met;
		}

		public Colour getColour() {
			return colour;
		}

		public void setOther(Colour other) throws InterruptedException {
			this.other = other;
		}
	}

	public class MeetingPlace {
		
		int n;

		public MeetingPlace(int n) {
			this.n = n;
		}
		
		Creature other = null;
		public void meet(Creature c) throws InterruptedException {
			
			synchronized (this) {
				if (n > 0) {
					if (other == null) {
						other = c;
						this.wait();
					} else {
						other.setOther(c.getColour());
						c.setOther(other.getColour());
						other = null;
						n--;
						this.notify();
					}
				} else {
					c.setOther(Colour.FADED);
				}
			}
		}
	}

	public chameneos(int n) throws InterruptedException {
		int meetings = 0;
		mp = new MeetingPlace(n);
		
		for (int i = 0; i < COLOURS.length; i++) {
			creatures[i] = new Creature(COLOURS[i], mp);
			creatures[i].start();
		}

		// wait for all threads to complete
		for (int i = 0; i < COLOURS.length; i++)
			creatures[i].join();
		
		// sum all the meetings
		for (int i = 0; i < COLOURS.length; i++) {
			meetings += creatures[i].getCreaturesMet();			
		}

		System.out.println(meetings);
	}

	public static void main(String[] args) throws Exception {
		if (args.length < 1)
			throw new IllegalArgumentException();
		new chameneos(Integer.parseInt(args[0]));
	}
}

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