String 转 List<Long>
String string = "1, 2, 3, 4";
List<Long> list = Arrays.asList(string.split(",")).stream().map(s -> Long.parseLong(s.trim())).collect(Collectors.toList());
List<Long> 转 String
String str = Arrays.toString(listIds.toArray()); //[1,2,3,3,4]
List<String> list = new ArrayList<>(2);
list.add("guan");
list.add("bao");
String[] array = list.toArray(new String[0]);
String[] str = new String[] { "yang", "hao" };
List list = Arrays.asList(str);
仍然为数组,不可使用add/remove/clear方法。