String [] turn List, List transfer String []

1. List 转换为 String数组
   List list = new ArrayList();
   list.add(“a”);
   list.add(“b”);
   String[] arr = list.toArray(new String[list.size()]);

2. String array is converted List
   String [] = ARR new new String [] { "C", "D"};
   List List = Arrays.asList (ARR); // This collection operation can not add elements
   List list1 = new ArrayList (list) ; // this collection side operating element