CopyOnWriteArrayList 不支持 Collections.sort()

异常信息：

Exception in thread "main" java.lang.UnsupportedOperationException
at java.util.concurrent.CopyOnWriteArrayList$COWIterator.set(CopyOnWriteArrayList.java:1049)
at java.util.Collections.sort(Collections.java:221)

jdk1.7 CopyOnWriteArrayList 不支持Collections.sort()
jdk1.8 CopyOnWriteArrayList 是支持Collections.sort() 的