Wrap Word

 
import java.text.BreakIterator;
import java.util.Locale;

public class Main {
  public static void main(String[] argv){
    System.out.println(wordWrap("this is a test", 10, Locale.CANADA) );
  }
  public static String wordWrap(String input, int width, Locale locale) {
    if (input == null) {
      return "";
    } else if (width < 5) {
      return input;
    } else if (width >= input.length()) {
      return input;
    }
    StringBuilder buf = new StringBuilder(input);
    boolean endOfLine = false;
    int lineStart = 0;

    for (int i = 0; i < buf.length(); i++) {
      if (buf.charAt(i) == '\n') {
        lineStart = i + 1;
        endOfLine = true;
      }
      if (i > lineStart + width - 1) {
        if (!endOfLine) {
          int limit = i - lineStart - 1;
          BreakIterator breaks = BreakIterator.getLineInstance(locale);
          breaks.setText(buf.substring(lineStart, i));
          int end = breaks.last();

          // if the last character in the search string isn't a space,
          // we can't split on it (looks bad). Search for a previous
          // break character
          if (end == limit + 1) {
            if (!Character.isWhitespace(buf.charAt(lineStart + end))) {
              end = breaks.preceding(end - 1);
            }
          }

          // if the last character is a space, replace it with a \n
          if (end != BreakIterator.DONE && end == limit + 1) {
            buf.replace(lineStart + end, lineStart + end + 1, "\n");
            lineStart = lineStart + end;
          }
          // otherwise, just insert a \n
          else if (end != BreakIterator.DONE && end != 0) {
            buf.insert(lineStart + end, '\n');
            lineStart = lineStart + end + 1;
          } else {
            buf.insert(i, '\n');
            lineStart = i + 1;
          }
        } else {
          buf.insert(i, '\n');
          lineStart = i + 1;
          endOfLine = false;
        }
      }
    }

    return buf.toString();
  }

}