Reformatting a Java String

Question

I have a string that looks like this:

CALDARI_STARSHIP_ENGINEERING

and I need to edit it to look like

Caldari Starship Engineering

Unfortunately it's three in the morning and I cannot for the life of me figure this out. I've always had trouble with replacing stuff in strings so any help would be awesome and would help me understand how to do this in the future.

Answer 1

    String s = "CALDARI_STARSHIP_ENGINEERING";
    String camel = "";
    for (String word : s.split("_"))
        camel += " " + word.charAt(0) + word.substring(1).toLowerCase();
    camel = camel.substring(1);

Answer 2

Untested, but thats how I implemented the same some time ago:

s = "CALDARI_STARSHIP_ENGINEERING";
StringBuilder b = new StringBuilder();
boolean upper = true;
for(char c : s.toCharArray()) {
    if( upper ) {
        b.append(c);
        upper = false;
    } else if( c = '_' ) {
        b.append(" ");
        upper = true;
    } else {
        b.append(Character.toLowerCase(c));
    }
}
s = b.toString();

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Answer 3

You can try this:

String originalString = "CALDARI_STARSHIP_ENGINEERING";
String newString =
    WordUtils.capitalize(originalString.replace('_', ' ').toLowerCase());

WordUtils are part of the Commons Lang libraries (http://commons.apache.org/lang/)

Answer 4

Quick and dirty way:

Lower case all

   line.toLowerCase();

Split into words:

   String[] words = line.split("_");

Then loop through words capitalising first letter:

  words[i].substring(0, 1).toUpperCase() 

Answer 5

Something like this is simple enough:

    String text = "CALDARI_STARSHIP_ENGINEERING";
    text = text.replace("_", " ");
    StringBuilder out = new StringBuilder();
    for (String s : text.split("\\b")) {
        if (!s.isEmpty()) {
            out.append(s.substring(0, 1) + s.substring(1).toLowerCase());
        }
    }
    System.out.println("[" + out.toString() + "]");
    // prints "[Caldari Starship Engineering]"

This split on the word boundary anchor.

See also

• regular-expressions.info/Word boundary

---

Matcher loop solution

If you don't mind using StringBuffer, you can also use Matcher.appendReplacement/Tail loop like this:

    String text = "CALDARI_STARSHIP_ENGINEERING";
    text = text.replace("_", " ");

    Matcher m = Pattern.compile("(?<=\\b\\w)\\w+").matcher(text);
    StringBuffer sb = new StringBuffer();
    while (m.find()) {
        m.appendReplacement(sb, m.group().toLowerCase());
    }
    m.appendTail(sb);
    System.out.println("[" + sb.toString() + "]");
    // prints "[Caldari Starship Engineering]"

The regex uses assertion to match the "tail" part of a word, the portion that needs to be lowercased. It looks behind (?<=...) to see that there's a word boundary \b followed by a word character \w. Any remaining \w+ would then need to be matched so it can be lowercased.

Related questions

• Use Java and RegEx to convert casing in a string
  • Java regex does not support Perl preprocessing operations \l \u, \L, and \U.
• Java split is eating my characters.
  • More examples of using assertions
• StringBuilder and StringBuffer in Java
  • Unfortunately, appendReplacement/Tail only takes StringBuffer

Answer 6

Using reg-exps:

String s = "CALDARI_STARSHIP_ENGINEERING";
StringBuilder camel = new StringBuilder();
Matcher m = Pattern.compile("([^_])([^_]*)").matcher(s);
while (m.find())
    camel.append(m.group(1)).append(m.group(2).toLowerCase());