Java List, Set, Map, 数组间的相互转换

1.list转set

Set set = new HashSet(new ArrayList()); 

2.set转list

List list = new ArrayList(new HashSet());

3.数组转为list

List stooges = Arrays.asList("Larry", "Moe", "Curly");

或者

String[] arr = {"1", "2"};List list = Arrays.asList(arr);

4.数组转为set

int[] a = { 1, 2, 3 };Set set = new HashSet(Arrays.asList(a));

5.map的相关操作

Map map = new HashMap();map.put("1", "a");map.put('2', 'b');map.put('3', 'c');System.out.println(map);// 输出所有的值System.out.println(map.keySet());// 输出所有的键System.out.println(map.values());// 将map的值转化为ListList list = new ArrayList(map.values());System.out.println(list);// 将map的值转化为SetSet set = new HashSet(map.values());System.out.println(set);

6.list转数组

List list = Arrays.asList("a","b");String[] arr = (String[])list.toArray(new String[list.size()]);System.out.println(Arrays.toString(arr));

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