/* CS 1520 Summer 2011 Java Example 2
   Simple introduction to using threads.  This program shows the basics of using
   threads in Java.  In this case the Thread class is extended and each thread
   object "runs on itself".
*/
import javax.swing.*;

class MyThread extends Thread  // extending the Thread class
{
    int id;      // id number for thread
    int outputs; // how many prints to do

    public MyThread(int id, int iter)
    {
        this.id = id;   // simple constructor to give object its id and
        this.outputs = iter;  // number of iterations
    }

    public void run()   // This method will be implicitly called when the
    {                   // thread is started.  run() is the sole method
                        // required for the Runnable interface, which Threads
                        // implement.  We override it in our own Thread classes
                        // to have the Thread "run" the way we want it to.
        int i = 1;
        while (i <= outputs)    // iterate outputs times
        {
              System.out.println("Thread " + id + " iterating for " +
                                 i + "th out of " + outputs + " times");
              try
              {
                   Thread.sleep(500);
              }
              catch (InterruptedException e)  // when a Thread calls the static
                                              // method sleep(), it is required
                          // to catch (or pass on with a throws clause) the
                          // exception shown above (it is a checked exception)
              {
                   System.out.println("Hey, who woke me? ");
              }
              i++;
        }

        // The code below demonstrates how threads are switched in and out of
        // the running state
        for (int j = 1; j <= 160; j++)
        {
              System.out.print(id);
              if (j % 80 == 0) System.out.println();
        }
        // The run() method begins executing when the start() method of a Thread
        // is called.  The Thread will continue to "run" until either the run()
        // method completes or it is abnormally terminated (ex. due to an
        // exception).  However, due to scheduling and shared data access
        // concerns, a Thread may not always be actively "running".
    }
}

public class ex2
{
    static int getNumThreads() // Get number of Threads (with error checking)
    {
         int val = 0;
         while (true)
         {
             try
             {
                  val = Integer.parseInt(
                           JOptionPane.showInputDialog("How many threads?"));
                  break;
             }
             catch (NumberFormatException e)
             {
                  JOptionPane.showMessageDialog(null,"Not an integer!");
             }
         }
         return val;
    }

    public static void main(String [] argv)
    {
         int num_threads;
         num_threads = getNumThreads();

         System.out.println("There will be " + num_threads + " threads");
         MyThread [] T = new MyThread[num_threads];  // array of MyThread
                       // created, but no actual MyThreads exist yet
                       // (since it is an array of references)

         for (int i = 0; i < T.length; i++)
         {
                T[i] = new MyThread(i, 3);  // Creating a new MyThread object
                T[i].start();               // Starting it running
         }

		 System.out.println("Main is done");  // Note when this message appears
    }
}