// Returns a version of the input where all contiguous
// whitespace characters are replaced with a single
// space. Line terminators are treated like whitespace.
public static CharSequence removeDuplicateWhitespace(CharSequence inputStr) {
    String patternStr = "\s+";
    String replaceStr = " ";
    Pattern pattern = Pattern.compile(patternStr);
    Matcher matcher = pattern.matcher(inputStr);
    return matcher.replaceAll(replaceStr);
}