Question

Say I have something like this (and I do)

class QueBean extends JPanel {
    private Queue queue = new LinkedBlockingQueue();

    public Object poll(){
        return queue.poll();
    }
}

with some of these that run on their own threads

class ConsumerBean extends JPanel implements Runnable{
    private QueBean queBean;

    public synchronized run(){
        while (true) {
           Object result =  queBean.poll();
           if (result != null) {
              jResultTextField.setText("got one");  
           }
           wait(500);
        }
    }
}

Should my poll() in the QueBean be synchronized or not?

Answer 1

External synchronization is not necessary in this case. Read the BlockingQueue contract:

BlockingQueue implementations are
thread-safe. All queuing methods
achieve their effects atomically using
internal locks or other forms of
concurrency control.