/**
 * A philosopher who thinks, gets hungry and eats with two forks.
 * 
 * @author Franck van Breugel
 */
public abstract class Philosopher extends Thread {
	private int id;

	private static final int THINKING = 0;
	private static final int HUNGRY = 1;
	private static final int EATING = 2;

	private static int[] state = { 0, 0, 0, 0, 0 };

	/**
	 * Initialize this philosopher with the given id.
	 * 
	 * @param id the id of this philosopher.
	 */
	public Philosopher(int id) {
		this.id = id;
	}

	/**
	 * Life of this philosopher.
	 */
	public void run() {
		while (true) {
			// think
			// becomes hungry
			synchronized (this) {
				Philosopher.state[this.id] = Philosopher.HUNGRY;
				while (Philosopher.state[(this.id - 1) % Philosopher.state.length] == Philosopher.EATING
						|| Philosopher.state[(this.id + 1) % Philosopher.state.length] == Philosopher.EATING) {
					try {
						this.wait();
					} catch (InterruptedException e) {
						e.printStackTrace();
					}
				}
				Philosopher.state[this.id] = Philosopher.EATING;
			}
			// eat
			synchronized (this) {
				Philosopher.state[this.id] = Philosopher.THINKING;
				if (Philosopher.state[(this.id - 1) % Philosopher.state.length] == Philosopher.HUNGRY
						|| Philosopher.state[(this.id + 1) % Philosopher.state.length] == Philosopher.HUNGRY) {
					this.notifyAll();
				}
			}
		}
	}
}