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 including current date  I just need that String representation to milliseconds  Do I have to write custom method  which will split and calculate milliseconds  or Is there any other way to do this  Thanks   I have tried as follows           String startAfter    00 01 30 555           SimpleDateFormat dateFormat   new SimpleDateFormat  HH mm ss SSS            Date date   dateFormat parse startAfter           System out println date getTime

User · Answer

If you want to use SimpleDateFormat  you could write   private final SimpleDateFormat sdf       new SimpleDateFormat  yyyy-MM-dd HH mm ss SSS          sdf setTimeZone TimeZone getTimeZone  GMT        private long parseTimeToMillis final String time  throws ParseException       return sdf parse  1970-01-01     time  getTime        But a custom method would be much more efficient  SimpleDateFormat  because of all its calendar support  time-zone support  daylight-savings-time support  and so on  is pretty slow  The slowness is worth it if you actually need some of those features  but since you don t  it might not be   It depends how often you re calling this method  and whether efficiency is a concern for your application    Also  SimpleDateFormat is non-thread-safe  which is sometimes a pain   Without knowing anything about your application  I can t guess whether that matters    Personally  I d probably write a custom method

User · Answer

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

User · Answer

Using JODA   PeriodFormatter periodFormat   new PeriodFormatterBuilder      minimumParsedDigits 2     appendHour      2 digits minimum    appendSeparator         minimumParsedDigits 2     appendMinute      2 digits minimum    appendSeparator         minimumParsedDigits 2     appendSecond      appendSeparator         appendMillis3Digit      toFormatter    Period result   Period parse string  periodFormat   return result toStandardDuration   getMillis

User · Answer

You can use SimpleDateFormat to do it  You just have to know 2 things     All dates are internally represented in UTC  getTime   returns the number of milliseconds since 1970-01-01 00 00 00 UTC      package se wederbrand milliseconds   import java text SimpleDateFormat  import java util Date  import java util TimeZone   public class Main               public static void main String   args  throws Exception           SimpleDateFormat sdf   new SimpleDateFormat  yyyy-MM-dd HH mm ss SSS            sdf setTimeZone TimeZone getTimeZone  UTC              String inputString    00 01 30 500            Date date   sdf parse  1970-01-01     inputString           System out println  in milliseconds      date getTime

[java] How to convert HH:mm:ss.SSS to milliseconds?

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