class FooRunnable implements Runnable {
    int num;
    //for deadlock example:
     Object o1 = new Object();
     Object o2 = new Object();

    FooRunnable (int num) {
	this.num = num;
    }

    public void run() {
	//this is the task to do.  can be done by several threads


	System.out.println("before sleep "+num+" "+this+" "+
			   Thread.currentThread().getName());


	/*
	//thread runtime errors but has no effect on other threads:
	if (Thread.currentThread().getName().equals("Thread-2")) {
	System.out.println("I'm Thread-2. I'm going to crash");
	//throw new Exception("puke");  //has to be reported throws by method
	TestThreads.ta[0].start();  //runtime error to restart a thread
	}
	*/
	
	/*
	try {  Thread.sleep(200); }
	catch (InterruptedException e) {}
	System.out.println("after sleep "+num+this+" "+
			   Thread.currentThread().getName());
	*/

	/*
	//have one thread join on another:
	if (Thread.currentThread().getName().equals("Thread-1")) {
	System.out.println("I'm Thread-1");
	try {TestThreads.ta[15].join();} //wait until Thread-16 ends}
	catch (InterruptedException e) {}
	System.out.println("I'm Thread-1 after 16 ends");
	}
	*/
	
	/*
	if (num == 2) {
	    System.out.println(Thread.currentThread().getName()+
			       " before synchmethod call");
	    synchedmethod();
	    System.out.println(Thread.currentThread().getName()+
			       " after synchmethod call");
	}
	*/

	/*
	// deadlock
	//if the two Objects are local here, no deadlock??  duh the objects
	//are separate in each thread.
	if (Thread.currentThread().getName().equals("Thread-1")) {
	    //get lock on o1, sleep so thread2 can get lock on o2
	    synchronized (o1) {
		System.out.println(Thread.currentThread().getName()+
				   " in outer synch block");
		try {  Thread.sleep(3000); }
		catch (InterruptedException e) {}
		System.out.println(Thread.currentThread().getName()+
				       " before inner synch block");
		synchronized (o2) {
		    System.out.println(Thread.currentThread().getName()+
				       " in inner synch block");
		}
		System.out.println(Thread.currentThread().getName()+
				   " after inner synch block");
	    }
	}
	if (Thread.currentThread().getName().equals("Thread-2")) {
	    synchronized (o2) {
		System.out.println(Thread.currentThread().getName()+
				   " in outer synch block");
		try {  Thread.sleep(3000); }
		catch (InterruptedException e) {System.out.println("caught");}
		System.out.println(Thread.currentThread().getName()+
				   " before inner synch block");
		synchronized (o1) {
		    System.out.println(Thread.currentThread().getName()+
				       " in inner synch block");
		}
		System.out.println(Thread.currentThread().getName()+
				   " after inner synch block");
	    }
	}
	*/

	/*
	//wait-notify example:
	if (Thread.currentThread().getName().equals("Thread-1")) {
	    //synch on Thread-2 (before it does notify
	    System.out.println(Thread.currentThread().getName()+
			       "before synch block");
	    synchronized(TestThreads.ta[1]) {
		System.out.println(Thread.currentThread().getName()+
				   " in synch block before wait call");
		try {
		    TestThreads.ta[1].wait();
		}
		catch (InterruptedException e) {
		    System.out.println(Thread.currentThread().getName()+
				       " caught InterruptedException");
		}

		System.out.println(Thread.currentThread().getName()+
				   " after wait call");
	    }
	    System.out.println(Thread.currentThread().getName()+
			       "after synch block");
	}
	if (Thread.currentThread().getName().equals("Thread-2")) {
	    //synch on self
	    System.out.println(Thread.currentThread().getName()+
			       "before synch block");
	    synchronized(this) {
		System.out.println(Thread.currentThread().getName()+
				   " in synch block before notify call");
		notify();
		System.out.println(Thread.currentThread().getName()+
				   " after notify call");
	    }
	    System.out.println(Thread.currentThread().getName()+
			       "after synch block");
	}
	*/


    }

    //method of FooRunnable, not Thread
    public void othermethod() {
	System.out.println(Thread.currentThread().getName()+" othermethod");
    }

    public synchronized void synchedmethod() {
	System.out.println(Thread.currentThread().getName()+
			   " in synchmethod call");
	try {  Thread.sleep(3000); }
	catch (InterruptedException e) {}
    }
}




public class TestThreads {
    final static int maxthreads=16;
    static Thread[] ta = new Thread[maxthreads];  //instead of local to main.  so that can be accessed by Foo objects

    public static void main (String [] args) {
	FooRunnable[] ra = new FooRunnable[4];
	//FooRunnable r = new FooRunnable();
	for (int i=0; i<4; i++) {
	    ra[i] = new FooRunnable(i);   //runnable object
	    for (int j=0; j<4; j++) {

		//use this to have references to the threads:
		ta[i*4+j] = new Thread(ra[i]);  //4 threads
		//use this to just instantiate threads and start them:
		//new Thread(ra[i]).start();
		/*
		if (i*4+j == 0)
		    System.out.println("thread 0 isAlive() or not before start: "+
				       ta[0].isAlive());
		*/
		//comment out if not having references to the threads
		ta[i*4+j].start();

		/*
		if (i*4+j == 0)
		    System.out.println("thread 0 isAlive() or not before start: "+
				       ta[0].isAlive());
		*/
		
	    }
	}
	//ta[0].start();  //runtime error, re-starting dead thread
	System.out.println("main "+Thread.currentThread().getName());

	/*
	try {
	    //ta[2].join();     //wait until thread-3 ends its run
	    for (int i=0; i<maxthreads; i++)
		ta[i].join();    //wait until all threads are done
	}
	catch (InterruptedException e) {}
	*/

	/*
	//currentThread will be main!
	ra[0].othermethod();  //but can call other methods of Runnable object
	*/
    }
}