str list 数组 map set转换

   str list 数组  map set转换

str转数组: char[] ch = hello.toCharArray();

list和set : Set set = new HashSet(new ArrayList());  List list = new ArrayList(new HashSet());
list转数组: String[] arr = (String[])list.toArray(new String[list.size()]);

数组转为list: List stooges = Arrays.asList("Larry", "Moe", "Curly");//该list长度不能变
数组转为set: Set set = new HashSet(Arrays.asList(a));

map的相关操作
map转化为List: List list = new ArrayList(map.values());  
map转化为Set: Set set = new HashSet(map.values());