diningphilosophers.java

Java 程序设计源码 只提供了部分

import java.util.*;

//定义 超时类
class Timeout extends Timer {
  public Timeout(int delay, final String msg) {
    super(true);

    super.schedule(
        new TimerTask() {
          public void run() {
            System.out.println(msg);
          }
        }, delay);
  }
}

//Chopstick 类 的 定义
class Chopstick {
  //static 全局变量
  private static int counter = 0;
  private int number = counter++;

  public String toString() {
    return "Chop " + number;
  }
}

class Philosopher extends Thread {
  //产生 随机 时间 作为 Philosopher 的思考时间
  private static Random rand = new Random();
  private static int counter = 0;
  private int number = counter++;
  private Chopstick leftChopstick;
  private Chopstick rightChopstick;

  static int ponder = 0;

  public Philosopher(Chopstick left, Chopstick right) {
    leftChopstick = left;
    rightChopstick = right;

    start();
  }

  public void think() {
    //this 代表 Philosopher
    System.out.println(this + " thinking");

    if(ponder > 0) {
      try {
        //睡眠 ponder 毫秒 相当于 思考
        sleep(rand.nextInt(ponder));
      }
      catch(InterruptedException e) {
        throw new RuntimeException(e);
      }
    }
  }

  public void eat() {
    //同步左边的 Chopstick
    synchronized(leftChopstick) {
      System.out.println(this + " has " + this.leftChopstick + " waiting "
          + this.rightChopstick);

      synchronized(rightChopstick) {
        System.out.println(this + " is eatting.");
      }
    }
  }

  public String toString() {
    return "Philosopher " + number;
  }

  public void run() {
    while(true) {
      think();
      eat();
    }
  }
}

public class DiningPhilosophers {
  public static void main(String[] args) {
    if(args.length < 3) {
      System.err.println("use method: \n" + "Philosopher number " + "thinking time\n");

      System.exit(0);
    }

    Philosopher[] philosopher = new Philosopher[Integer.parseInt(args[0])];

    Philosopher.ponder = Integer.parseInt(args[1]);

    Chopstick
        left = new Chopstick(),
        right = new Chopstick(),

    first = left;

    int i = 0;

    while(i < philosopher.length - 1) {
      philosopher[i++] = new Philosopher(left, right);
      left = right;

      right = new Chopstick();
    }

    if(args[2].equals("DeadLock")) {
      philosopher[i] = new Philosopher(left, first);
    }
    else {
      philosopher[i] = new Philosopher(first, left);
    }

    if(args.length > 4) {
      int delay = Integer.parseInt(args[3]);

      if(delay != 0) {
        new Timeout(delay * 1000, "time over");
      }
    }
  }
}