java - Collections.synchronizedList 和同步

Question

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

这里真的需要 block “同步(列表){}”吗？

Answer 1

您不需要像您在示例中那样进行同步。但是，非常重要的是，您需要在迭代时围绕列表进行同步(如 Javadoc 中所述):

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());   
}