The title pretty much says it all. What's the simplest/most elegant way that I can convert, in Java, a string from the format "THIS_IS_AN_EXAMPLE_STRING" to the format "ThisIsAnExampleString"? I figure there must be at least one way to do it using String.replaceAll() and a regex, but I've really never understood Java regexes.
My initial thoughts are: prepend the string with an underscore (_), convert the whole string to lower case, and then use replaceAll to convert every character preceded by an underscore with its uppercase version.
views:
1366answers:
4
+5
A:
static String toCamelCase(String s){
String[] parts = s.split("_");
String camelCaseString = "";
for (String part : parts){
camelCaseString = camelCaseString + toProperCase(part);
}
return camelCaseString;
}
static String toProperCase(String s) {
return s.substring(0, 1).toUpperCase() +
s.substring(1).toLowerCase();
}
Note: You need to add argument validation.
C. Ross
2009-07-17 15:24:24
Nice answer, but it would be a little better if either the method name described the fact that the string was split or that logic was externalised and the method calls aligned as a pipe, e.g. "THIS_IS_AN_EXAMPLE_STRING".removeUnderscores().toCamelCase()This is more reusable.
Dan Gravell
2009-07-22 09:14:45
That's not necessarily *better* (though yes, it is more reusable). When it comes to name formatting conventions, camelcase can/does imply not using underscores; on the reverse side of the coin, there are conventions which specify using underscores. So in my mind, this is just a method to convert from one format to another.
Matt Ball
2009-07-24 15:27:27
+2
A:
String input = "ABC_DEF";
StringBuilder sb = new StringBuilder;
for( String oneString : input.split("_") )
{
sb.append( oneString.substring(0,1) );
sb.append( oneString.substring(1).toLowerCase() );
}
//sb now holds your desired string
Alex B
2009-07-17 15:28:53
+12
A:
Take a look at WordUtils in the Apache Commons lang library: http://commons.apache.org/lang/api-2.3/org/apache/commons/lang/WordUtils.html
Specifically, the capitalizeFully(String str, char[] delimiters) method should do the job:
String blah = "LORD_OF_THE_RINGS";
assertEquals("LordOfTheRings", WordUtils.capitalizeFully(blah, new char[]{'_'}).replaceAll("_", ""));
Green bar!
Dan Gravell
2009-07-17 15:34:34
No sir! We should rewrite these existing, already-working utilities ourselves, for we are proper programmers!
skaffman
2009-07-17 15:41:58
It's 16:42 on a Friday afternoon. I'll let everyone else rewrite it, I'm going out for a beer \o/ ;)
Dan Gravell
2009-07-17 15:43:11
More to the point, I don't even have access to that particular package with my current setup, and since I really don't (yet) need anything beyond the capitalizeFully method, I lose nothing by writing it myself.
Matt Ball
2009-07-21 20:31:44
I respect your decision Matt, it's probably the right thing to do in your position. However, consider the following:* Someone else in your team decides they need a routine to swap the case of letters. They implement it. You now have ~20 lines to maintain. You would have ~2 if you used the library. And don't forget the unit tests!* The accepted answer has a downside in that the method name does not describe what the code does. A well reused API like the commons stuff rarely has those downsides.The point is that maintenance is the biggest cost of software. Generally, re-use is a good idea.
Dan Gravell
2009-07-22 09:12:08
+1
A:
public static void main(String[] args) {
String start = "THIS_IS_A_TEST";
StringBuffer sb = new StringBuffer();
for (String s : start.split("_")) {
sb.append(Character.toUpperCase(s.charAt(0)));
if (s.length() > 1) {
sb.append(s.substring(1, s.length()).toLowerCase());
}
}
System.out.println(sb);
}
Yishai
2009-07-17 15:39:13