StringUtils.hasLength(null) = false;

  StringUtils.hasLength("") = false;

  StringUtils.hasLength(" ") = true;

  StringUtils.hasLength("Hello") = true;  

  StringUtils.hasText(null) = false;

  StringUtils.hasText("") = false;

  StringUtils.hasText(" ") = false;

  StringUtils.hasText("12345") = true;

  StringUtils.hasText(" 12345 ") = true;  

  //是否包含空白字符

  StringUtils.containsWhitespace(null)=false;

  StringUtils.containsWhitespace("")=false;

  StringUtils.containsWhitespace("a")=false;

  StringUtils.containsWhitespace("abc")=false;

  StringUtils.containsWhitespace("abc")=false;

  StringUtils.containsWhitespace(" ")=true;

  StringUtils.containsWhitespace(" a")=true;

  StringUtils.containsWhitespace("abc ")=true;

  StringUtils.containsWhitespace("a b")=true

  StringUtils.containsWhitespace("a  b")  

  StringUtils.trimWhitespace(null)=null;

  StringUtils.trimWhitespace("")="";

  StringUtils.trimWhitespace(" ")="";

  StringUtils.trimWhitespace("/t")="";

  StringUtils.trimWhitespace(" a")="a";

  StringUtils.trimWhitespace("a ")="a";

  StringUtils.trimWhitespace(" a ")="a";

  StringUtils.trimWhitespace(" a b ")="a b";  

  StringUtils.trimLeadingWhitespace(null)=null;

  StringUtils.trimLeadingWhitespace("")="";

  StringUtils.trimLeadingWhitespace(" ")="";

  StringUtils.trimLeadingWhitespace("/t")="";

  StringUtils.trimLeadingWhitespace(" a")="a";

  StringUtils.trimLeadingWhitespace("a ")="a ";

  StringUtils.trimLeadingWhitespace(" a ")="a ";

  StringUtils.trimLeadingWhitespace(" a b ")="a b "

  StringUtils.trimLeadingWhitespace(" a b  c ")="a b  c "  

  StringUtils.trimTrailingWhitespace(null)=null;

  StringUtils.trimTrailingWhitespace(" ")="";

  StringUtils.trimTrailingWhitespace("/t")="";

  StringUtils.trimTrailingWhitespace("a ")="a";

  StringUtils.trimTrailingWhitespace(" a")=" a";

  StringUtils.trimTrailingWhitespace(" a ")=" a";

  StringUtils.trimTrailingWhitespace(" a b ")=" a b";

  StringUtils.trimTrailingWhitespace(" a b  c ")=" a b  c";  

  StringUtils.trimAllWhitespace("")="";

  StringUtils.trimAllWhitespace(" ")="";

  StringUtils.trimAllWhitespace("/t")="";

  StringUtils.trimAllWhitespace(" a")="a";

  StringUtils.trimAllWhitespace("a ")="a";

  StringUtils.trimAllWhitespace(" a ")="a";

  StringUtils.trimAllWhitespace(" a b ")="ab";

  StringUtils.trimAllWhitespace(" a b  c "="abc";

  // 统计一个子字符串在字符串出现的次数

  StringUtils.countOccurrencesOf(null, null) == 0;

  StringUtils.countOccurrencesOf("s", null) == 0;

  StringUtils.countOccurrencesOf(null, "s") == 0;

  StringUtils.countOccurrencesOf("erowoiueoiur", "WERWER") == 0;

  StringUtils.countOccurrencesOf("erowoiueoiur", "x")=0;

  StringUtils.countOccurrencesOf("erowoiueoiur", " ") == 0;

  StringUtils.countOccurrencesOf("erowoiueoiur", "") == 0;

  StringUtils.countOccurrencesOf("erowoiueoiur", "e") == 2;

  StringUtils.countOccurrencesOf("erowoiueoiur", "oi") == 2;

  StringUtils.countOccurrencesOf("erowoiueoiur", "oiu") == 2;

  StringUtils.countOccurrencesOf("erowoiueoiur", "oiur") == 1;

  StringUtils.countOccurrencesOf("erowoiueoiur", "r") == 2;  

  //字符串替换

  String inString = "a6AazAaa77abaa";

  String oldPattern = "aa";

  String newPattern = "foo";

  // Simple replace

  String s = StringUtils.replace(inString, oldPattern, newPattern);

  s.equals("a6AazAfoo77abfoo")=true;  

  // Non match: no change

  s = StringUtils.replace(inString, "qwoeiruqopwieurpoqwieur", newPattern);

  s.equals(inString)=true

  s = StringUtils.replace(inString, oldPattern, null);

  s.equals(inString)=true  

  // Null old pattern: should ignore

  s = StringUtils.replace(inString, null, newPattern);

         s.equals(inString)=true  

  //删除字符串

  String inString = "The quick brown fox jumped over the lazy dog";

  String noThe = StringUtils.delete(inString, "the");

  noThe.equals("The quick brown fox jumped over  lazy dog")=true;

  String nohe = StringUtils.delete(inString, "he");

  nohe.equals("T quick brown fox jumped over t lazy dog")=true;

  String nosp = StringUtils.delete(inString, " ");

  nosp.equals("Thequickbrownfoxjumpedoverthelazydog")=true;

  String killEnd = StringUtils.delete(inString, "dog");

  killEnd.equals("The quick brown fox jumped over the lazy ")=true;

  String mismatch = StringUtils.delete(inString, "dxxcxcxog");

   mismatch.equals(inString)=true;  

  //删除任何字符

  //源代码如下

  //char c = inString.charAt(i);

  //如果不存在 c 值，则返回 -1

  //if (charsToDelete.indexOf(c) == -1) {

  //out.append(c);

  //}  

  String inString = "Able was I ere I saw Elba";  

  String res = StringUtils.deleteAny(inString, "I");

         res.equals("Able was  ere  saw Elba")=true;

  res = StringUtils.deleteAny(inString, "AeEba!");

  res.equals("l ws I r I sw l")=true;

  String mismatch = StringUtils.deleteAny(inString, "#@$#$^");

  mismatch.equals(inString)=true;  

  //源代码如下 return (str != null ? "'" + str + "'" : null);

  assertEquals("'myString'", StringUtils.quote("myString"));

  assertEquals("''", StringUtils.quote(""));

  assertNull(StringUtils.quote(null));

  //将第一个字符改大写

  StringUtils.capitalize(Str)

  //将第一个个字符改小写

  StringUtils.uncapitalize(str)  

  //mypath/myfile.txt" -> "myfile.txt

  //获取字符串文件名和扩展名

  StringUtils.getFilename("myfile").equals("myfile")=true;

  StringUtils.getFilename("mypath/myfile".equals("myfile")=true;

  StringUtils.getFilename("mypath/myfile".equals("myfile")=true;

  StringUtils.getFilename("myfile.txt").equals("myfile.txt")=true;

  StringUtils.getFilename("mypath/myfile.txt").equals("myfile.txt")=true;  

  // 获取字符串扩展名,以.分隔

  StringUtils.getFilenameExtension("myfile")=null;

  StringUtils.getFilenameExtension("myPath/myfile")=null;

  StringUtils.getFilenameExtension("myfile.").equals("")=true;

  StringUtils.getFilenameExtension("myPath/myfile.").equals("")=true;

  StringUtils.StringUtils.getFilenameExtension("myfile.txt").equals("txt")=true;

  StringUtils.getFilenameExtension("mypath/myfile.txt").equals("txt")=true;  

  //舍去文件名扩展名

  StringUtils.stripFilenameExtension(null)=true;

  StringUtils.stripFilenameExtension("").equals("")=true;

  StringUtils.stripFilenameExtension("myfile").equals("myfile")=true;

  StringUtils.stripFilenameExtension("mypath/myfile").equals("mypath/myfile")=true;

  StringUtils.stripFilenameExtension("myfile.").equals("myfile")=true;

  StringUtils.stripFilenameExtension("mypath/myfile.").equals("mypath/myfile")=true;

  StringUtils.stripFilenameExtension("mypath/myfile.").equals("mypath/myfile")=true;

  StringUtils.stripFilenameExtension("myfile.txt").equals("myfile")=true;

  StringUtils.stripFilenameExtension("mypath/myfile.txt").equals("mypath/myfile")=true