Yurttas/PL/OOL/Java/F/07/02/DP00.java

 1/**
 2 *  Copyright(C) 1998
 3 *  All Rights Reserved. Salih Yurttas, ZCubes, BitsOfCode Software Systems, Inc..
 4 *
 5 *  Permission to use, copy, modify, and distribute this
 6 *  software and its documentation for EDUCATIONAL purposes
 7 *  and without fee is hereby granted provided that this
 8 *  copyright notice appears in all copies.
 9 *
10 *  @date   : January 1, 1998.
11 *  @author : Salih Yurttas.
12 */
13
14
15class Fork {
16
17  private boolean free = true;
18
19  synchronized void pickUp() {
20    while(!free) {
21      try {
22        wait();
23      }
24      catch(Exception e) {
25        Thread.currentThread().stop();
26      }
27    }
28    free = false;
29  }
30
31  synchronized void putDown() {
32    free = true;
33    notify();
34  }
35
36}
37
38class Philosopher implements Runnable {
39
40  private Fork a,
41               b;
42  int n;
43
44  Philosopher(int n,
45              Fork a,
46              Fork b) {
47    this.a = a;
48    this.b = b;
49    this.n = n;
50  }
51
52  public void run(){
53    while(true) {
54      a.pickUp();
55      b.pickUp();
56
57      System.out.println("Philosopherosopher " +
58                         n +
59                         " is eating");
60
61      b.putDown();
62      a.putDown();
63    }
64  }
65
66}
67
68class DP00 {
69
70  public static void main(String[] argv){
71    int size = 5;
72    Fork[] forks = new Fork[size];
73
74    for(int i=0; i<size; ++i)
75      forks[i] = new Fork();
76
77    for(int i=0; i<size; ++i ) {
78      Fork a = forks[i];
79      Fork b = forks[(i+1)%size];
80      Philosopher p;
81
82      if(i%2==0)
83        p = new Philosopher(i,
84                            a,
85                            b);
86      else
87        p = new Philosopher(i,
88                            b,
89                            a);
90      new Thread(p).start();
91    }
92  }
93
94}