StringUtils的使用，数组转list，list转数组

数组转list：

1）、方法1：
String[] userid = {“aa”,”bb”,”cc”};
List userList = new ArrayList();
Collections.addAll(userList, userid);
2）、方法2：
String[] userid = {“aa”,”bb”,”cc”};
List userList = Arrays.asList(userid);
另：Arrays.asList()返回一个受指定数组支持的固定大小的列表。所以不能做Add、Remove等操作。
List list = new ArrayList(Arrays.asList(userid));这样操作就可以了。

StringUtils的使用

：自己写String的处理繁琐，这些常用工具都有：
参考官网
StringUtils官网

<dependency>
   <groupId>commons-langgroupId>
   <artifactId>commons-langartifactId>
   <version>2.6version>
dependency>

• IsEmpty/IsBlank - checks if a String contains text
• Trim/Strip - removes leading and trailing whitespace
• Equals - compares two strings null-safe
• startsWith - check if a String starts with a prefix null-safe
• endsWith - check if a String ends with a suffix null-safe
• IndexOf/LastIndexOf/Contains - null-safe index-of checks
• IndexOfAny/LastIndexOfAny/IndexOfAnyBut/LastIndexOfAnyBut - index-of any of a set of Strings
• ContainsOnly/ContainsNone/ContainsAny - does String contains only/none/any of these characters
• Substring/Left/Right/Mid - null-safe substring extractions
• SubstringBefore/SubstringAfter/SubstringBetween - substring extraction relative to other strings
• Split/Join - splits a String into an array of substrings and vice versa
• Remove/Delete - removes part of a String
• Replace/Overlay - Searches a String and replaces one String with another
• Chomp/Chop - removes the last part of a String
• LeftPad/RightPad/Center/Repeat - pads a String
• UpperCase/LowerCase/SwapCase/Capitalize/Uncapitalize - changes the case of a String
• CountMatches - counts the number of occurrences of one String in another
• IsAlpha/IsNumeric/IsWhitespace/IsAsciiPrintable - checks the characters in a String
• DefaultString - protects against a null input String
• Reverse/ReverseDelimited - reverses a String
• Abbreviate - abbreviates a string using ellipsis
• Difference - compares Strings and reports on their differences
• LevensteinDistance - the number of changes needed to change one String into another

MapUtils、CollectionUtils等的使用：

这个jar包的功能很像jdk中的Collection的功能，可以认为是它的扩充，有各种常用的map，set，list，Collection等的各种常用方法， 加速你的编码过程，而且这些东西，是比较官方的，是经得起考验的，比自己匆忙之下写的肯定要优雅好多，要多学多用。

参考官网：
MapUtils、CollectionUtils等的使用

<dependency>
  <groupId>commons-collectionsgroupId>
  <artifactId>commons-collectionsartifactId>
  <version>3.2.1version>
dependency>