/*
 * ThreadExample1
 * by Robert Keller
 *
 * A first example of Java threads, using "implements Runnable"
 * (as opposed to "extends Thread").
 *
 * Two threads are created. Each sleeps for an amount 'delay' of
 * milliseconds, then wakes up and prints its step number.
 *
 * Due to difference in delay values, we expect thread 2 to progress
 * at roughly double the rate of thread 1.
 */

class ThreadExample1 implements Runnable
{
Thread myThread;	// Thread object for control

int myID;		// Identifier for this "thread"

int step;		// Step number of this "thread"

int delay; 		// delay milliseconds

/**
 * Construct a ThreadExample1 with the specified ID and delay value.
 */

public ThreadExample1(int myID, int delay)
    {
    this.myID = myID;
    this.delay = delay;
    myThread = new Thread(this);
    step = 1;
    }

/**
 * Start this thread.
 * The run method will be called.
 */

public void start()
    {
    myThread.start();
    }

/**
 * The run() method required to implement the Runnable interface.
 */

public void run()
    {
    while( true )
        {
        // try/catch is needed because sleep can throw an exception.

        try
            {
            myThread.sleep(delay);
            System.out.println("thread " + myID + " is at step " + step);
            step++;
            }
        catch( Exception e )
            {
            }
        }
    }

public static void main(String arg[])
    {
    ThreadExample1 thread1 = new ThreadExample1(1, 1000);
    ThreadExample1 thread2 = new ThreadExample1(2, 500);

    thread1.start();
    thread2.start();
    }

}