CopyOnWriteArrayList.java和ArrayList.java，这2个类的构造函数，注释中有一句话 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 public ArrayList(Collection c) { elementData = c.toArray(); size = elementData.length; // c.toArray might (incorrectly) not return Object[] (see 6