How can I use a thread's method from the other thread?

Question

After looking through tutorial on http://oreilly.com/catalog/expjava/excerpt/index.html below is what I have written. I wanted thread_B to be able to call one of the methods declared in thread_A

thread_A = new Thread(new Worker());
thread_A.start();

thread_B = new Thread(new Communicator(thread_A));
thread_B.start();

Initializing the thread and assigning it to the class variable seems to work fine. However, it does not seem to allow me to use the thread_A's method.

//in thread_B, 
Thread worker;
public Communicator(Thread worker){
    this.worker = worker;
}
//if I want to call thead_A's method size()
public void run(){
    this.worker.queue.size(); //DOES NOT WORK
}

I just want thread_B to know about thread_A's queue information. What is a good approach to solve this problem?

Answer 1

Do it like this:

Worker w = new Worker();
thread_A = new Thread(w);
thread_B = new Thread(new Communicator(w));

and change Communicator 's constructor to take a Worker rather than a Thread .

Answer 2

The attribute queue is not part of the Thread class. Is it part of the Worker class?

If so then the code needs to be written something like

worker = new Worker();
thread_A = new Thread(worker);
thread_A.start();

thread_B = new Thread(new Communicator(worker));
thread_B.start();


//in thread_B, 
Worker worker;
public Communicator(Worker worker){
    this.worker = worker;
}

//if I want to call thead_A's method size()
public void run(){
    this.worker.queue.size(); //print out queue size in thread_A
}

Answer 3

Threads don't have methods. Classes have methods. Just retain a reference to whichever object reference you need to call the method on, and call it.