1. For the following program, explain the interesting elements related to threads.
You may experiment with the program using the attached source code: TaskThreadDemo source code
1 public class TaskThreadDemo {
2 public static void main (String args []) {
3 String [] sa = {"a", "X", "+","."};
4 for (String s: sa) {
5 Runnable ps = new PrintChar (s, 200);
6 Thread ts = new Thread (ps, s);
7 ts.start ();
8 } // end for each character
9 } // end main
10 } // end class TaskThreadDemo
11
12 class PrintChar implements Runnable {
13 String ch;
14 int times;
15
16 public PrintChar (String c, int n) {
17 ch = c;
18 times = n;
19 } // end constructor
20
21 public void run () {
22 for (int i = 0; i < times; i++) {
23 System.out.print (ch);
24 } // end for loop
25 } // end method run
26 } // end class PrintChar
2. What is changed if the method called on line 7, start(), is replaced with run()? Explain (of course).
3. What is changed if the method Thread.yield() is added between lines 23 and 24? Explain.
4. List and explain the threads running in your Sorcerer's Cave program as reported by jconsole. Note that you can name the threads created in the program, as is done on line 6 in Problem 1 above, which can make this discussion a lot easier to follow.
5. Explain how the java.util.concurrent.Semaphore class can be used in the Sorcerer's Cave program, final project, to coordinate the requirements of the various jobs. Then address the question of whether or not this actually makes sense in the context of the requirements of program. In other words, can you suggest approaches to handling shared resource pools that would be simpler than using semaphores?