数组转String

String[] arr =new String[]{1,2,3,4,5};
System.out.println(Arrays.toString(arr));

List转String

#java8
List<String> lists = Arrays.asList("1","2","3","4","5");
#方法一
String str1= String.join("," , lists);

#方法二
String str2 = lists.stream().collect(Collectors.joining(","))

List 转 数组

ArrayList<String> list=new ArrayList<String>();
String[] strings = new String[list.size()];
list.toArray(strings);