Notes: Tuesday 28 October 2003

Schedule

Schedule Revisions: The schedule below reflects changes from the original schedule:

• Problem Set 6 will be the last problem set; there is no Problem Set 7.
• Exam 2 will be handed out on Tuesday, 2 December, and due on Friday, 5 December. Exam 2 will be comprehensive, but similar in length and format to Exam 1. There will be no final exam. Students who believe they would benefit from having a final exam should meet with me (before December 2) to arrange an alternative.

• Thursday, 30 October: PS5 Part 1
• Tuesday, 11 November: PS5 Part 2
• Tuesday, 18 November: No class
• Tuesday, 25 November: PS6 Due
• Tuesday, 2 December: Exam 2 Out
• Friday, 5 December: Exam 2

Programming Concurrency

class Counter {
   private int count;
   public Counter () { count = 0; }
   public void increment () { count++; }
   public void decrement () { count--; }
   public int getValue () { return count; }
}
  
class IncThread extends Thread {
   private Counter c;
   public IncThread (Counter p_c) { c = p_c; }
   public void run () {
       while (true) {
           c.increment ();
           System.err.println ("Running inc thread: " + currentThread () 
                                       + " / Value: " + c.getValue ());
       }
   }
}

class DecThread extends Thread {
   private Counter c;
   public DecThread (Counter p_c) { c = p_c; }
   public void run () {
       while (true) {
            c.decrement ();
            System.err.println ("Running dec thread: " + currentThread () 
                                        + " / Value: " + c.getValue ());
      }
   }
}

public class Yarn {
    public static void main (String args[]) {
         Counter c = new Counter ();
         IncThread ithread = new IncThread (c);
         DecThread dthread = new DecThread (c);
         ithread.start ();
         dthread.start ();
    }
}

University of Virginia Department of Computer Science CS 201J: Engineering Software

Sponsored by the National Science Foundation

cs201j-staff@cs.virginia.edu