Threads and calling methods on it explicitly

[Abimaran Kugathasan]

Please confirm this sentence, Whether it's correct or not. I got it from a web.

We can only invoke the start() or stop() methods, when the thread is in New thread state. Calling any method besides start() or stop() will cause an IllegalThreadStateException.

But, my opinion is:

Thread one = new Thread();
Thread two = new Thread();
one.run();
two.run();

Here, the threads will run sequentially, first thread one runs, when it exists, the thread two starts.

Thread one = new Thread();
Thread two = new Thread();
one.start();
two.start();

Here, the start() method call run() asynchronously (doesn't wait for any result, just fire up an action), while we run run() method synchronously. we wait when it quits and only we can run the next line of our code.

Please correct, if I wrong! Thanks in Advanced!

[Minhaj Mehmood]

Abimaran Kugathasan wrote:Please confirm this sentence, Whether it's correct or not. I got it from a web.

We can only invoke the start() or stop() methods, when the thread is in New thread state. Calling any method besides start() or stop() will cause an IllegalThreadStateException.

well the statement is correct regarding start() method lets say if a thread is already in running state, if you again call start() it will cause IllegalThreadStateException for sure....
but I'm not sure about stop give a try your self write a piece of code and test....


hth

[Ankit Garg]

1. The Thread.stop method has been deprecated, so you don't have to worry about that for the exam.
2. calling run method directly doesn't start a new thread, so the call is synchronous, calling the start method starts a new thread and invokes the run method asynchronously...

[Abimaran Kugathasan]

Hi, So we can invoked any method rather than start() and stop() on a new thread. It's ok, that calling run() method on threads don't start a thread of execution. That's fine.
My question is What is the purpose of the IllegalThreadStateException in java?

Can we call any methods on a Runnable thread as like new Thread. Please clarify this. Thanks in Advanced!

[Ankit Garg]

My question is What is the purpose of the IllegalThreadStateException in java?

It is thrown when you perform any action on a thread object which is not allowed because of the current state of the thread. Like if you call the start method on a thread twice, you'll get an IllegalThreadStateException as a thread can only be started once...