Truncating Strings by Bytes

Question

I create the following for truncating a string in java to a new string with a given number of bytes.

        String truncatedValue = \"\";
        String curren         


        

Answer 1

As noted, Peter Lawrey solution has major performance disadvantage (~3,500msc for 10,000 times), Rex Kerr was much better (~500msc for 10,000 times) but the result not was accurate - it cut much more than it needed (instead of remaining 4000 bytes it remainds 3500 for some example). attached here my solution (~250msc for 10,000 times) assuming that UTF-8 max length char in bytes is 4 (thanks WikiPedia):

public static String cutWord (String word, int dbLimit) throws UnsupportedEncodingException{
    double MAX_UTF8_CHAR_LENGTH = 4.0;
    if(word.length()>dbLimit){
        word = word.substring(0, dbLimit);
    }
    if(word.length() > dbLimit/MAX_UTF8_CHAR_LENGTH){
        int residual=word.getBytes("UTF-8").length-dbLimit;
        if(residual>0){
            int tempResidual = residual,start, end = word.length();
            while(tempResidual > 0){
                start = end-((int) Math.ceil((double)tempResidual/MAX_UTF8_CHAR_LENGTH));
                tempResidual = tempResidual - word.substring(start,end).getBytes("UTF-8").length;
                end=start;
            }
            word = word.substring(0, end);
        }
    }
    return word;
}