在java中，我们经常需要对List、Array等做一些转换操作，当然转换方法有很多种，但哪种方法既方便又高效呢？在这里向大家介绍一下集合间的最佳转换方法。
1.List转换为Array
List<String> list = new ArrayList<String>();
list.add("China");
list.add("Switzerland");
list.add("Italy");
list.add("France");
String [] countries = list.toArray(new String[list.size()]);
2.Array转换为List
String[] countries = {"China", "Switzerland", "Italy", "France"};
List list = Arrays.asList(countries);
3.Map转换为List
List<Value> list = new ArrayList<Value>(map.values());
4.Array转换为Set
String [] countries = {"India", "Switzerland", "Italy"};
Set<String> set = new HashSet<String>(Arrays.asList(countries));
System.out.println(set);
5.Map转换为Set
Map<Integer, String> sourceMap = createMap(); Set<String> targetSet = new HashSet<>(sourceMap.values());
