上述代碼傳回”harry; ron; hermione”。另外，usefornull(string)方法可以給定某個字元串來替換null，而不像skipnulls()方法是直接忽略null。 joiner也可以用來連接配接對象類型，在這種情況下，它會把對象的tostring()值連接配接起來。
警告：joiner執行個體總是不可變的。用來定義joiner目智語義的配置方法總會傳回一個新的joiner執行個體。這使得joiner執行個體都是線程安全的，你可以将其定義為static final常量。
jdk内建的字元串拆分工具有一些古怪的特性。比如，string.split悄悄丢棄了尾部的分隔符。 問題：”,a,,b,”.split(“,”)傳回？
“”, “a”, “”, “b”, “”
null, “a”, null, “b”, null
“a”, null, “b”
“a”, “b”
以上都不對
上述代碼傳回iterable<string>，其中包含”foo”、”bar”和”qux”。splitter可以被設定為按照任何模式、字元、字元串或字元比對器拆分。
<b>方法</b><b></b>
<b>描述</b><b></b>
<b>範例</b><b></b>
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/splitter.html#on(char)">splitter.on(char)</a>
按單個字元拆分
splitter.on(‘;’)
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/splitter.html#on(com.google.common.base.charmatcher)">splitter.on(charmatcher)</a>
按字元比對器拆分
splitter.on(charmatcher.breaking_whitespace)
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/splitter.html#on(java.lang.string)">splitter.on(string)</a>
按字元串拆分
splitter.on(“, “)
按正規表達式拆分
splitter.onpattern(“\r?\n”)
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/splitter.html#fixedlength(int)">splitter.fixedlength(int)</a>
按固定長度拆分；最後一段可能比給定長度短，但不會為空。
splitter.fixedlength(3)
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/splitter.html#omitemptystrings()">omitemptystrings()</a>
從結果中自動忽略空字元串
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/splitter.html#trimresults()">trimresults()</a>
移除結果字元串的前導空白和尾部空白
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/splitter.html#trimresults(com.google.common.base.charmatcher)">trimresults(charmatcher)</a>
給定比對器，移除結果字元串的前導比對字元和尾部比對字元
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/splitter.html#limit(int)">limit(int)</a>
限制拆分出的字元串數量
如果你想要拆分器傳回list，隻要使用lists.newarraylist(splitter.split(string))或類似方法。 警告：splitter執行個體總是不可變的。用來定義splitter目智語義的配置方法總會傳回一個新的splitter執行個體。這使得splitter執行個體都是線程安全的，你可以将其定義為static final常量。
在以前的guava版本中，stringutil類瘋狂地膨脹，其擁有很多處理字元串的方法：allascii、collapse、collapsecontrolchars、collapsewhitespace、indexofchars、lastindexnotof、numsharedchars、removechars、removecrlf、replacechars、retainallchars、strip、stripandcollapse、stripnondigits。 所有這些方法指向兩個概念上的問題：
怎麼才算比對字元？
如何處理這些比對字元？
為了收拾這個泥潭，我們開發了charmatcher。
然而使用charmatcher的好處更在于它提供了一系列方法，讓你對字元作特定類型的操作：修剪[trim]、折疊[collapse]、移除[remove]、保留[retain]等等。charmatcher執行個體首先代表概念1：怎麼才算比對字元？然後它還提供了很多操作概念2：如何處理這些比對字元？這樣的設計使得api複雜度的線性增加可以帶來靈活性和功能兩方面的增長。
注：charmatcher隻處理char類型代表的字元；它不能了解0x10000到0x10ffff的unicode 增補字元。這些邏輯字元以代理對[surrogate pairs]的形式編碼進字元串，而charmatcher隻能将這種邏輯字元看待成兩個獨立的字元。
charmatcher中的常量可以滿足大多數字元比對需求：
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#any">any</a>
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#none">none</a>
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#whitespace">whitespace</a>
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#breaking_whitespace">breaking_whitespace</a>
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#invisible">invisible</a>
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#digit">digit</a>
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#java_letter">java_letter</a>
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#java_digit">java_digit</a>
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#java_letter_or_digit">java_letter_or_digit</a>
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#java_iso_control">java_iso_control</a>
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#java_lower_case">java_lower_case</a>
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#java_upper_case">java_upper_case</a>
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#ascii">ascii</a>
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#single_width">single_width</a>
其他擷取字元比對器的常見方法包括：
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#anyof(java.lang.charsequence)">anyof(charsequence)</a>
枚舉比對字元。如charmatcher.anyof(“aeiou”)比對小寫英語元音
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#is(char)">is(char)</a>
給定單一字元比對。
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#inrange(char,%20char)">inrange(char, char)</a>
給定字元範圍比對，如charmatcher.inrange(‘a’, ‘z’)
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#collapsefrom(java.lang.charsequence,%20char)">collapsefrom(charsequence, char)</a>
把每組連續的比對字元替換為特定字元。如whitespace.collapsefrom(string, ‘ ‘)把字元串中的連續空白字元替換為單個空格。
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#matchesallof(java.lang.charsequence)">matchesallof(charsequence)</a>
測試是否字元序列中的所有字元都比對。
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#removefrom(java.lang.charsequence)">removefrom(charsequence)</a>
從字元序列中移除所有比對字元。
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#retainfrom(java.lang.charsequence)">retainfrom(charsequence)</a>
在字元序列中保留比對字元，移除其他字元。
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#trimfrom(java.lang.charsequence)">trimfrom(charsequence)</a>
移除字元序列的前導比對字元和尾部比對字元。
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/charmatcher.html#replacefrom(java.lang.charsequence,%20java.lang.charsequence)">replacefrom(charsequence, charsequence)</a>
用特定字元序列替代比對字元。
所有這些方法傳回string，除了matchesallof傳回的是boolean。
不要這樣做字元集處理：
試試這樣寫：
caseformat被用來友善地在各種ascii大小寫規範間轉換字元串——比如，程式設計語言的命名規範。caseformat支援的格式如下：
<b>格式</b><b></b>
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/caseformat.html#lower_camel">lower_camel</a>
lowercamel
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/caseformat.html#lower_hyphen">lower_hyphen</a>
lower-hyphen
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/caseformat.html#lower_underscore">lower_underscore</a>
lower_underscore
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/caseformat.html#upper_camel">upper_camel</a>
uppercamel
<a href="http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/caseformat.html#upper_underscore">upper_underscore</a>
upper_underscore
caseformat的用法很直接：
我們caseformat在某些時候尤其有用，比如編寫代碼生成器的時候。
![Java小案例——随機數猜測随機數猜測[圖]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)