Thread, start(), run() confusion

[mark juszczec]

This is making me a little crazy:

class Cert                      
{
    static int hamburger=0;
    public static void main(String[] args) throws Exception 
    {
        Thread thread = new Thread(new Runnable()
        {
        public void run()
        {
            hamburger++;
            System.out.println(hamburger);
        }});
        thread.run(); hamburger++;
        // #1 
        thread.start(); 
        thread.run(); 
        // #2
    }
}

Ok. So the first thread.run() calls the run() method defined in new Runnable(), but why isn't thread.start() necessary before calling thread.run()?

I told myself maybe thread.start() isn't needed when you are using Runnable.

So then why doesn't thread.start() cause some kind of exception because the thread is already running?

By the time we get to the 2nd thread.run(), I don't know what the heck is going on.

Are there 2 different threads? What did thread.start() really start?

Why does this thing work?

Mark

[jeya velan]

thread.run();

The above is like calling a method on object.It is executed in the same call stack.Does not create new thread.

thread.start();

Calling start() actually creates new Thread of execution.

System.out.println(Thread.currentThread().getName());

If you add the above SOP to your run method you can see what happens.

[mark juszczec]

Ok, NOW I get it.

I was stuck thinking in "Thread mode" where everything in the problem was a thread.

[Alexander Sales]

This is really a good one! Keep up in knowing the pitfalls