null
List list = new ArrayList();
List<StageDO> list = new ArrayList();
list when used to instantiate, or a null pointer newspaper
list.addAll(不能为空)
(不能为空).equals(不能为空)
List list = new ArrayList();
List<StageDO> list = new ArrayList();
list when used to instantiate, or a null pointer newspaper
list.addAll(不能为空)
(不能为空).equals(不能为空)