How to convert HH:mm:ss.SSS to milliseconds?

Question

I have a String 00:01:30.500 which is equivalent to 90500 milliseconds. I tried using SimpleDateFormat which give milliseconds includi

Answer 1

If you want to parse the format yourself you could do it easily with a regex such as

private static Pattern pattern = Pattern.compile("(\\d{2}):(\\d{2}):(\\d{2}).(\\d{3})");

public static long dateParseRegExp(String period) {
    Matcher matcher = pattern.matcher(period);
    if (matcher.matches()) {
        return Long.parseLong(matcher.group(1)) * 3600000L 
            + Long.parseLong(matcher.group(2)) * 60000 
            + Long.parseLong(matcher.group(3)) * 1000 
            + Long.parseLong(matcher.group(4)); 
    } else {
        throw new IllegalArgumentException("Invalid format " + period);
    }
}

However, this parsing is quite lenient and would accept 99:99:99.999 and just let the values overflow. This could be a drawback or a feature.