list采坑记录一下

List<Integer> cards = Lists.newArrayList(6,10,11,12,21,23,29,30,38,39,42,43,46,51,53,59,60);
List<Integer> copyList = Lists.newArrayList();
copyList = cards;
copyList.remove(2);
System.out.println("cards:"+cards);
System.out.println("copyList:"+copyList);

用了等号的操作结果是

cards:[6, 10, 12, 21, 23, 29, 30, 38, 39, 42, 43, 46, 51, 53, 59, 60]
copyList:[6, 10, 12, 21, 23, 29, 30, 38, 39, 42, 43, 46, 51, 53, 59, 60]

List<Integer> cards = Lists.newArrayList(6,10,11,12,21,23,29,30,38,39,42,43,46,51,53,59,60);
List<Integer> copyList = Lists.newArrayList();
copyList.addAll(cards);
copyList.remove(2);
System.out.println("cards:"+cards);
System.out.println("copyList:"+copyList);

用了add的结果

cards:[6, 10, 11, 12, 21, 23, 29, 30, 38, 39, 42, 43, 46, 51, 53, 59, 60]
copyList:[6, 10, 12, 21, 23, 29, 30, 38, 39, 42, 43, 46, 51, 53, 59, 60]

用等号操作时两个集合都会被操作，add不会