问题
I\'d like to write a method that converts CamelCase into a human-readable name.
Here\'s the test case:
public void testSplitCamelCase() {
assertEquals(\"lowercase\", splitCamelCase(\"lowercase\"));
assertEquals(\"Class\", splitCamelCase(\"Class\"));
assertEquals(\"My Class\", splitCamelCase(\"MyClass\"));
assertEquals(\"HTML\", splitCamelCase(\"HTML\"));
assertEquals(\"PDF Loader\", splitCamelCase(\"PDFLoader\"));
assertEquals(\"A String\", splitCamelCase(\"AString\"));
assertEquals(\"Simple XML Parser\", splitCamelCase(\"SimpleXMLParser\"));
assertEquals(\"GL 11 Version\", splitCamelCase(\"GL11Version\"));
}
回答1:
This works with your testcases:
static String splitCamelCase(String s) {
return s.replaceAll(
String.format("%s|%s|%s",
"(?<=[A-Z])(?=[A-Z][a-z])",
"(?<=[^A-Z])(?=[A-Z])",
"(?<=[A-Za-z])(?=[^A-Za-z])"
),
" "
);
}
Here's a test harness:
String[] tests = {
"lowercase", // [lowercase]
"Class", // [Class]
"MyClass", // [My Class]
"HTML", // [HTML]
"PDFLoader", // [PDF Loader]
"AString", // [A String]
"SimpleXMLParser", // [Simple XML Parser]
"GL11Version", // [GL 11 Version]
"99Bottles", // [99 Bottles]
"May5", // [May 5]
"BFG9000", // [BFG 9000]
};
for (String test : tests) {
System.out.println("[" + splitCamelCase(test) + "]");
}
It uses zero-length matching regex with lookbehind and lookforward to find where to insert spaces. Basically there are 3 patterns, and I use String.format to put them together to make it more readable.
The three patterns are:
UC behind me, UC followed by LC in front of me
XMLParser AString PDFLoader
/\ /\ /\
non-UC behind me, UC in front of me
MyClass 99Bottles
/\ /\
Letter behind me, non-letter in front of me
GL11 May5 BFG9000
/\ /\ /\
References
- regular-expressions.info/Lookarounds
Related questions
Using zero-length matching lookarounds to split:
- Regex split string but keep separators
- Java split is eating my characters
回答2:
You can do it using org.apache.commons.lang.StringUtils
StringUtils.join(
StringUtils.splitByCharacterTypeCamelCase("ExampleTest"),
' '
);
回答3:
The neat and shorter solution :
StringUtils.capitalize(StringUtils.join(StringUtils.splitByCharacterTypeCamelCase("yourCamelCaseText"), StringUtils.SPACE)); // Your Camel Case Text
回答4:
If you don't like "complicated" regex's, and aren't at all bothered about efficiency, then I've used this example to achieve the same effect in three stages.
String name =
camelName.replaceAll("([A-Z][a-z]+)", " $1") // Words beginning with UC
.replaceAll("([A-Z][A-Z]+)", " $1") // "Words" of only UC
.replaceAll("([^A-Za-z ]+)", " $1") // "Words" of non-letters
.trim();
It passes all the test cases above, including those with digits.
As I say, this isn't as good as using the one regular expression in some other examples here - but someone might well find it useful.
回答5:
You can use org.modeshape.common.text.Inflector.
Specifically:
String humanize(String lowerCaseAndUnderscoredWords, String... removableTokens)Capitalizes the first word and turns underscores into spaces and strips trailing "_id" and any supplied removable tokens.
Maven artifact is: org.modeshape:modeshape-common:2.3.0.Final
on JBoss repository: https://repository.jboss.org/nexus/content/repositories/releases
Here's the JAR file: https://repository.jboss.org/nexus/content/repositories/releases/org/modeshape/modeshape-common/2.3.0.Final/modeshape-common-2.3.0.Final.jar
回答6:
The following Regex can be used to identify the capitals inside words:
"((?<=[a-z0-9])[A-Z]|(?<=[a-zA-Z])[0-9]]|(?<=[A-Z])[A-Z](?=[a-z]))"
It matches every capital letter, that is ether after a non-capital letter or digit or followed by a lower case letter and every digit after a letter.
How to insert a space before them is beyond my Java skills =)
Edited to include the digit case and the PDF Loader case.
回答7:
I think you will have to iterate over the string and detect changes from lowercase to uppercase, uppercase to lowercase, alphabetic to numeric, numeric to alphabetic. On every change you detect insert a space with one exception though: on a change from upper- to lowercase you insert the space one character before.
回答8:
This works in .NET... optimize to your liking. I added comments so you can understand what each piece is doing. (RegEx can be hard to understand)
public static string SplitCamelCase(string str)
{
str = Regex.Replace(str, @"([A-Z])([A-Z][a-z])", "$1 $2"); // Capital followed by capital AND a lowercase.
str = Regex.Replace(str, @"([a-z])([A-Z])", "$1 $2"); // Lowercase followed by a capital.
str = Regex.Replace(str, @"(\D)(\d)", "$1 $2"); //Letter followed by a number.
str = Regex.Replace(str, @"(\d)(\D)", "$1 $2"); // Number followed by letter.
return str;
}
回答9:
For the record, here is an almost (*) compatible Scala version:
object Str { def unapplySeq(s: String): Option[Seq[Char]] = Some(s) }
def splitCamelCase(str: String) =
String.valueOf(
(str + "A" * 2) sliding (3) flatMap {
case Str(a, b, c) =>
(a.isUpper, b.isUpper, c.isUpper) match {
case (true, false, _) => " " + a
case (false, true, true) => a + " "
case _ => String.valueOf(a)
}
} toArray
).trim
Once compiled it can be used directly from Java if the corresponding scala-library.jar is in the classpath.
(*) it fails for the input "GL11Version" for which it returns "G L11 Version".
回答10:
I took the Regex from polygenelubricants and turned it into an extension method on objects:
/// <summary>
/// Turns a given object into a sentence by:
/// Converting the given object into a <see cref="string"/>.
/// Adding spaces before each capital letter except for the first letter of the string representation of the given object.
/// Makes the entire string lower case except for the first word and any acronyms.
/// </summary>
/// <param name="original">The object to turn into a proper sentence.</param>
/// <returns>A string representation of the original object that reads like a real sentence.</returns>
public static string ToProperSentence(this object original)
{
Regex addSpacesAtCapitalLettersRegEx = new Regex(@"(?<=[A-Z])(?=[A-Z][a-z]) | (?<=[^A-Z])(?=[A-Z]) | (?<=[A-Za-z])(?=[^A-Za-z])", RegexOptions.IgnorePatternWhitespace);
string[] words = addSpacesAtCapitalLettersRegEx.Split(original.ToString());
if (words.Length > 1)
{
List<string> wordsList = new List<string> { words[0] };
wordsList.AddRange(words.Skip(1).Select(word => word.Equals(word.ToUpper()) ? word : word.ToLower()));
words = wordsList.ToArray();
}
return string.Join(" ", words);
}
This turns everything into a readable sentence. It does a ToString on the object passed. Then it uses the Regex given by polygenelubricants to split the string. Then it ToLowers each word except for the first word and any acronyms. Thought it might be useful for someone out there.
回答11:
I'm not a regex ninja, so I'd iterate over the string, keeping the indexes of the current position being checked & the previous position. If the current position is a capital letter, I'd insert a space after the previous position and increment each index.
回答12:
http://code.google.com/p/inflection-js/
You could chain the String.underscore().humanize() methods to take a CamelCase string and convert it into a human readable string.
来源：https://stackoverflow.com/questions/2559759/how-do-i-convert-camelcase-into-human-readable-names-in-java