How to deal with Concurrency before you start coding [closed]

Answer 1

It's possible that the multi-threaded nature of your application might be a red herring, with respect to the ConcurrentModificationExceptions you mentioned: there are other ways that you can get a ConcurrentModificationException that don't necessarily involve multiple threads. Consider the following:

List items = new ArrayList();

//... some code adding items to the list

for (Item item : items) {
    if(item.isTheOneIWantToRemove()) {
        items.remove(item); //This will result in a ConcurrentModificationException
    }
}

Changing your for loop to a loop with an iterator, or an increasing index value solves the problem:

for (Iterator it = items.iterator(); it.hasNext();) {
    if(item.isTheOneIWantToRemove()) {
        it.remove(); //No exception thrown
    }
}

or

for (int i = 0; i < items.size(); i++) {
    if(item.isTheOneIWantToRemove()) {
        items.remove(items.get(i)); //No exception thrown
    }
}