string数组的定义有三种：
String arr[] = new String[10]; //创建一个长度为10的String 类型数组。
String arr[] = {"张三","李四"};
String[] str = new String[]{"","","","",""};
可以使用List方便 String[]转List
String[] arr = new String[]{"s1","s2","s3"};
List list = Arrays.asList(arr);
List转String[]
List list = new ArrayList();
list.add("s1");
list.add("s2");
list.add("s3");
String[] arr = list.toArray(new String[list.size()]);