Collections.synchronizedList and synchronized

Question

List<String> list = Collections.synchronizedList(new ArrayList<String>());
synchronized (list) {
    list.add("message");
}

Is the block "synchronized (list){} " really need here ?

Answer 1

You don't need to synchronize as you put in your example. HOWEVER, very important, you need to synchronize around the list when you iterate it (as noted in the Javadoc):

It is imperative that the user manually synchronize on the returned list when iterating over it:

List list = Collections.synchronizedList(new ArrayList());
...
synchronized(list) {
    Iterator i = list.iterator(); // Must be in synchronized block
    while (i.hasNext())
        foo(i.next());   
}