Regarding String manipulation

Question

I have a String str which can have list of values like below. I want the first letter in the string to be uppercase and if underscore appears in the string then i need to remove it and need to make the letter after it as upper case. The rest all letter i want it to be lower case.

""
"abc" 
"abc_def"
"Abc_def_Ghi12_abd"
"abc__de"
"_"
Output:
""
"Abc"
"AbcDef"
"AbcDefGhi12Abd"
"AbcDe"
""

Wow, that's a nice idea ... Hope you'll succeed without asking one of those beginners questions like "where is the doc for the String class saying all i could want about the methods I need to do my homework". — Riduidel, Mar 15 '10 at 10:17
So you have *one* string but apparently *four* individual “first” letters in that string? — Joey, Mar 15 '10 at 10:20
This is similar to what Commons Lang WordUtils.capitalize does. — Thilo, Mar 15 '10 at 10:23
Actually, it's very similar to another question of that user too: http://stackoverflow.com/questions/2375649/converting-to-upper-and-lower-case-in-java — Joey, Mar 15 '10 at 10:26

score 1 · Accepted Answer · edited May 23 '17 at 12:26

Well, without showing us that you put any effort into this problem this is going to be kinda vague.

I see two possibilities here:

Split the string at underscores, apply the answer from this question to each part and re-combine them.
Create a StringBuilder, walk through the string and keep track of whether you are
- at the start of the string
- after an underscore or
- somewhere else
and act appropriately on the current character before appending it to the StringBuilder instance.

Bozho · Answer 2 · 2010-03-15T10:50:55.197

1

replace _ with space (str.replace("_", " "))
use WordUtils.capitalizeFully(str); (from commons-lang)
replace space with nothing (str.replace(" ", ""))

edited Mar 15 '10 at 10:50

answered Mar 15 '10 at 10:42

Bozho

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score 0 · Answer 3 · answered Mar 15 '10 at 10:49

You can use following regexp based code:

public static String camelize(String input) {
  char[] c = input.toCharArray();
  Pattern pattern = Pattern.compile(".*_([a-z]).*");
  Matcher m = pattern.matcher(input);
  while ( m.find() ) {
    int index = m.start(1);
    c[index] = String.valueOf(c[index]).toUpperCase().charAt(0); 
  }
  return String.valueOf(c).replace("_", "");
}

Adrian Regan · Answer 4 · 2010-03-15T11:05:54.757

Use Pattern/Matcher in the java.util.regex package:

for each string that is in your array do the following:

StringBuffer output = new StringBuffer();
Matcher match = Pattern.compile("[^|_](\w)").matcher(inStr);
while(match.find()) {
   match.appendReplacement(output, matcher.match(0).ToUpper());
}
match.appendTail(output);

// Will have the properly capitalized string.
String capitalized = output.ToString();

The regular expression looks for either the start of the string or an underscore "[^|_]" Then puts the following character into a group "(\w)"

The code then goes through each of the matches in the input string capitalizing the first satisfying group.

Regarding String manipulation

4 Answers4