1.list转化成数组
List<String> strlist = new ArrayList<String>();
String[] array=(String[]) strlist.toArray(new String[strlist.size()]);
2.set转化成list
Set BoardSet=new HashSet<Board>();
this.boardList = new ArrayList<Board>(BoardSet);
3.list转化成set
List list = new ArrayList(new Hashset());
Set set = new HashSet(list);
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List list = Arrays.asList(array); //数组转化成list
list = new LinkedList(Arrays.asList(array));
Set set = new HashSet(Arrays.asList(array));
4.将map转化成数组
Map parent = new HashMap<String, String>();
Set set = parent.entrySet();