Pattern Error while using RegEx

[pk anoop]

Hi All,

I am stuck up with a problem while using Regular Expression.
My requirement is : split a long string into maximum size of 125 letters and then insert a line break in between them.
while splitting, it shouldn't split between the words. in short, i want to split a string into small strings whose length is 125 or at the end of word before 125th letter. Hope i didnt confused

i used one regexp to solve this, and believe me am an absolute zero in this.
i just got one code and copy pasted ;-)

  StringBuffer result = null;
			while(mailBody.trim().length() > 0){
				Matcher m = Pattern.compile("^.{0,125}\\b").matcher(mailBody);
				m.find();
				String oneLineString = m.group(0);
				if(result == null)
					result = new StringBuffer(oneLineString);
				else
					result.append("\n"+ oneLineString);
				mailBody = mailBody.substring(oneLineString.length(),mailBody.length()).trim();
			}  

this is my code, and it's working perfectly unless the starting string ends with a full stop(.).
In that case it is giving an error like : No match found.

Please help.

Regards,
Anoop P K

[David Newton]

I'm not even sure I'd use a regex for this, honestly.

[pk anoop]

i want to do it with optimum performance and just am eager about this regular expression also.
Otherwise how will you do it?
regards,
anoop

[Rob Spoor]

I'd go for a simple loop. For instance:

int index = 125;
while (index >= 0 && !Character.isWhitespace(s.charAt(index)))
{
    index--;
}
// index == -1 or s.charAt(index) is whitespace
if (index == -1)
{
    index = 125;
    while (index < s.length() && !Character.isWhitespace(s.charAt(index)))
    {
        index++;
    }
}
if (index == s.length())
{
    // no whitespace at all
}
else
{
    // index points to whitespace nearest to 125
    // index > 125 means that there is no whitespace in the first 125 chars
}