Difference between java HH mm and hh mm on SimpleDateFormat

Question

Whats the difference between kk mm  HH mm and hh mm formats         SimpleDateFormat broken   new SimpleDateFormat  kk mm ss        broken setTimeZone TimeZone getTimeZone  Etc UTC         SimpleDateFormat working   new SimpleDateFormat  HH mm ss        working setTimeZone TimeZone getTimeZone  Etc UTC         SimpleDateFormat working2   new SimpleDateFormat  hh mm ss        working setTimeZone TimeZone getTimeZone  Etc UTC          System out println broken format epoch        System out println working format epoch        System out println working2 format epoch      prints   24 00 00 00 00 00 05 30 00

User · Answer

kk   01-24  will look like 01  02  24   HH  00-23  will look like 00  01  23   hh  01-12 in AM PM  will look like 01  02  12   so the last printout  working2  is a bit weird  It should say 12 00 00   edit  if you were setting the working2 timezone and format  which  as kdagli pointed out  you are not

User · Answer

Please take a look here  HH is hour in a day  starting from 0 to 23   hh are hours in am pm format  kk is hour in day  starting from 1 to 24   mm is minute in hour  ss are the seconds in a minute

User · Answer

Actually the last one is not weird  Code is setting the timezone for working instead of working2   SimpleDateFormat working2   new SimpleDateFormat  hh mm ss    working setTimeZone TimeZone getTimeZone  Etc UTC      kk goes from 1 to 24  HH from 0 to 23 and hh from 1 to 12  AM PM    Fixing this error gives   24 00 00 00 00 00 01 00 00

User · Answer

Use the built-in localized formats  If this is for showing a time of day to a user  then in at least 19 out of 20 you don   t need to care about kk  HH nor hh  I suggest that you use something like this       DateTimeFormatter defaultTimeFormatter               DateTimeFormatter ofLocalizedTime FormatStyle SHORT       System out format   s   s n               Locale getDefault    LocalTime MIN format defaultTimeFormatter      The point is that it gives different output in different default locales  For example    en SS  12 00 AM fr BL  00 00 ps AF  0 00 es CO  12 00 a m     The localized formats have been designed to conform with the expectations of different cultures  So they generally give the user a better experience and they save you of writing a format pattern string  which is always error-prone   I furthermore suggest that you don   t use SimpleDateFormat  That class is notoriously troublesome and fortunately long outdated  Instead I use java time  the modern Java date and time API  It is so much nicer to work with   Four pattern letters for hour  H  h  k and K  Of course if you need to parse a string with a specified format  and also if you have a very specific formatting requirement  it   s good to use a format pattern string  There are actually four different pattern letters to choose from for hour  quoted from the documentation      Symbol  Meaning                     Presentation      Examples   ------  -------                     ------------      -------    h       clock-hour-of-am-pm  1-12   number            12    K       hour-of-am-pm  0-11         number            0    k       clock-hour-of-day  1-24     number            24    H       hour-of-day  0-23           number            0   In practice H and h are used  As far as I know k and K are not  they may just have been included for the sake of completeness   But let   s just see them all in action       DateTimeFormatter timeFormatter               DateTimeFormatter ofPattern  hh mm a  HH mm  kk mm  KK mm a   Locale ENGLISH       System out println LocalTime of 0  0  format timeFormatter        System out println LocalTime of 1  15  format timeFormatter        System out println LocalTime of 11  25  format timeFormatter        System out println LocalTime of 12  35  format timeFormatter        System out println LocalTime of 13  40  format timeFormatter       12 00 AM  00 00  24 00  00 00 AM 01 15 AM  01 15  01 15  01 15 AM 11 25 AM  11 25  11 25  11 25 AM 12 35 PM  12 35  12 35  00 35 PM 01 40 PM  13 40  13 40  01 40 PM    If you don   t want the leading zero  just specify one pattern letter  that is h instead of hh or H instead of HH  It will still accept two digits when parsing  and if a number to be printed is greater than 9  two digits will still be printed   Links   Oracle tutorial  Date Time explaining how to use java time  Documentation of DateTimeFormatter

User · Answer

h H   12 24 hours means you will write hh mm   12 hours format and HH mm   24 hours format

[java] Difference between java HH:mm and hh:mm on SimpleDateFormat

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