list,set,map,数组间的相互转换

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public class ListSetMap {public static void main(String[] args) {// list,set,map,数组间的相互转换// list转setSet<String> set1 = new HashSet<String>(new ArrayList<String>());set1.add("a");// 2.set转listList<String> list1 = new ArrayList<String>(new HashSet<String>());list1.add("a");// 3.数组转为listList<String> stooges = Arrays.asList("Larry", "Moe", "Curly");System.out.println(stooges.toString());// 或者String[] arr1 = { "1", "2" };List<String> list2 = Arrays.asList(arr1);System.out.println(list2.toString());// 4.数组转为setint[] a = { 1, 2, 3 };Set<Object> set2 = new HashSet<Object>(Arrays.asList(a));System.out.println(set2.toString());// 5.map的相关操作。Map<String, String> map = new HashMap<String, String>();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<String> list = new ArrayList<String>(map.values());System.out.println(list);// 将map的值转化为SetSet<String> set = new HashSet<String>(map.values());System.out.println(set);// 6.list转数组List<String> list3 = Arrays.asList("a", "b");String[] arr2 = (String[]) list3.toArray(new String[list.size()]);System.out.println(Arrays.toString(arr2));}}
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