Java下String逗号数组和List<String>的互相转换

public static String listToString(List<String> list){
if(list==null){
return null;
}
StringBuilder result = new StringBuilder();
boolean first = true;
//第一个前面不拼接","
for(String string :list) {
if(first) {
first=false;
}else{
result.append(",");
}
result.append(string);
}
return result.toString();
}

public static List<String> stringToList(String strs){
String str[] = strs.split(",");
return Arrays.asList(str);
}