subList() 的坑

1.subList(l,r) 是左闭右开 例如：subList(1,3) 截取的是下标为1和2两个元素

2.subList() 返回对象是RandomAccessSubList不可序列化的实例化

https://stackoverflow.com/questions/26568205/resolve-a-java-util-arraylistsublist-notserializable-exception

3.切记不要这么写：list = (LinkedList) list.subList(0, 2);

否则程序会这样报复你：java.util.SubList cannot be cast to java.util.LinkedList
向下转型的前提是你要先是那个类

总结：list = new ArrayList(list.subList(0, 2)); 这么写总没错啦～