Question

I have a very simple snippet of code that populates a vector, iterates through it, and then clears it. Here is basically what I’m trying in principle:

vector v = new Vector();
v.add(1);
v.add(2);
v.add(3);
ListIterator iter = v.listIterator();

while (iter.hasNext()) {
    System.out.println(iter.next());
}

v.clear()

But I get a ConcurrentModificationException.

From reading up on this, apparently using “synchronized” in some fashion is the solution. But I’m seeing a couple different approaches and am wondering what is the best, simplest way to resolve this in my case (with no explicit threads involved)?

Answer 1

Let me shorten that code for you:

Vector<Integer> v = new Vector<Integer>();
v.add(1);
v.add(2);
v.add(3);
for (Integer i: v) {
    System.out.println(i);
}
v.clear();

You shouldn’t use listIterator() unless you do forward and backward navigation. For simple iteration use the iterator() method, preferably in the for-each style I show above (where the actual iterator object is hidden from you).

And don’t use Vector!!! Use ArrayList instead.