单选题
Given:
ASet set = new TreeSet();
BSet set = new HashSet();
CSet set = new SortedSet();
DList set = new SortedList();
ESet set = new LinkedHashSet();
正确答案
答案解析
略
Which code, inserted at line 4, guarantees that this program will output [1, 2]（）?ASet set = new TreeSet();
BSet set = new HashSet();
CSet set = new SortedSet();
DList set = new SortedList();
ESet set = new LinkedHashSet();