{"id":119,"date":"2019-01-19T12:47:25","date_gmt":"2019-01-19T12:47:25","guid":{"rendered":"https:\/\/www.kindsonthegenius.com\/java\/?p=119"},"modified":"2020-08-06T09:54:15","modified_gmt":"2020-08-06T09:54:15","slug":"19-java-date-and-time-part-2","status":"publish","type":"post","link":"https:\/\/kindsonthegenius.com\/java\/19-java-date-and-time-part-2\/","title":{"rendered":"Java – Date and Time – Part 2"},"content":{"rendered":"

So we would just continue with Date and Time. You can review Date and Time Part 1<\/a> if you have not.<\/p>\n

 <\/p>\n

In this tutorial, we would cover the following<\/p>\n

    \n
  1. Formatting Date Using print()<\/a><\/li>\n
  2. Date and Time Conversion Codes<\/a><\/li>\n
  3. Converting Dates to Strings<\/a><\/li>\n
  4. Sleeping for Some Time<\/a><\/li>\n
  5. How to Get Elapsed Time<\/a><\/li>\n<\/ol>\n

     <\/p>\n

    1. Formatting Date Using printf()<\/strong><\/h4>\n

    Similar to the way you format string using printf, you can also format dates using printf. You can review Java Strings and Formatting.<\/a><\/p>\n

    Unlike formatting string, you use a two-letter format specifier to format dates. The first letter is t, then followed by a second letter indicating the format. So instead of %c, we have %tc. Instead of %d, we have %td. And so on.<\/p>\n

    For example, run the code in Listing 1.0 below.
    \n<\/p>\n

     <\/p>\n

    import<\/span> java.text.SimpleDateFormat<\/span>;<\/span>\r\nimport<\/span> java.util.Date<\/span>;<\/span>\r\n\r\npublic<\/span> class<\/span> DateDemo<\/span> {<\/span>\r\n\r\n\tpublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String[]<\/span> args)<\/span> {<\/span>\r\n\t\t\t\r\n\t\t\t\/\/Create a new date<\/span>\r\n\t\t\tDate date =<\/span> new<\/span> Date();<\/span>\r\n\t\t\t\r\n\t\t\t\/\/Format the date using String.format<\/span>\r\n\t\t\tString strDate =<\/span> String.<\/span>format<\/span>(<\/span>\"Today is %tc\"<\/span>,<\/span> date);<\/span>\r\n\t\t\t\r\n\t\t\t\/\/Print the date using printf()<\/span>\r\n\t\t\tSystem.<\/span>out<\/span>.<\/span>printf<\/span>(<\/span>strDate);<\/span>\t\t\t\t\t\r\n\t}<\/span>\r\n}<\/span>\r\n<\/pre>\n
    Listing 1.0: Formating date using String.Fomat and printf<\/p>\n
     <\/p>\n
    This code in Listing 1.0 uses %tc\u00a0 where c represents ‘complete date and time’. You can replace the %tc with %tD or %tF\u00a0 or %tr. All these gives the date in other formats. You can find the complete list of formats in the next section.<\/p>\n
     <\/p>\n
    2. Date and Time Conversion Codes<\/strong><\/h4>\n
    I would recommend you spend some time with the table below.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
    Character Code<\/th>\nBrief description<\/th>\nExample<\/th>\n<\/tr>\n
    c<\/td>\nComplete date and time<\/td>\nTue May 04 06:31:52 CDT 2019<\/td>\n<\/tr>\n
    F<\/td>\nISO 8601 date format<\/td>\n2018-02-09<\/td>\n<\/tr>\n
    D<\/td>\nU.S. formatted date (month\/day\/year)<\/td>\n02\/04\/2018<\/td>\n<\/tr>\n
    T<\/td>\n24-hour time format<\/td>\n13:05:19<\/td>\n<\/tr>\n
    r<\/td>\n12-hour time format<\/td>\n05:05:19 am<\/td>\n<\/tr>\n
    R<\/td>\n24-hour time, no seconds<\/td>\n15:06<\/td>\n<\/tr>\n
    Y<\/td>\n4-digit year (with leading zeroes)<\/td>\n2015<\/td>\n<\/tr>\n
    y<\/td>\nLast 2 digits of the year (with leading zeroes)<\/td>\n05<\/td>\n<\/tr>\n
    C<\/td>\nFirst 2 digits of the year (with leading zeroes)<\/td>\n25<\/td>\n<\/tr>\n
    B<\/td>\nFull month name<\/td>\nDecember<\/td>\n<\/tr>\n
    b<\/td>\nAbbreviated name of month<\/td>\nJul<\/td>\n<\/tr>\n
    m<\/td>\n2-digit month (with leading zeroes)<\/td>\n04<\/td>\n<\/tr>\n
    d<\/td>\n2-digit day (with leading zeroes)<\/td>\n01<\/td>\n<\/tr>\n
    e<\/td>\n2-digit day (without leading zeroes)<\/td>\n3<\/td>\n<\/tr>\n
    A<\/td>\nFull name of weekday<\/td>\nWednesday<\/td>\n<\/tr>\n
    a<\/td>\nAbbreviated name of weekday<\/td>\nFri<\/td>\n<\/tr>\n
    j<\/td>\n3-digit day of year (with leading zeroes)<\/td>\n057<\/td>\n<\/tr>\n
    H<\/td>\n2-digit hour (with leading zeroes), between 00 and 23<\/td>\n11<\/td>\n<\/tr>\n
    k<\/td>\n2-digit hour (without leading zeroes), between 0 and 23<\/td>\n19<\/td>\n<\/tr>\n
    I<\/td>\n2-digit hour (with leading zeroes), between 01 and 12<\/td>\n04<\/td>\n<\/tr>\n
    l<\/td>\n2-digit hour (without leading zeroes), between 1 and 12<\/td>\n8<\/td>\n<\/tr>\n
    M<\/td>\n2-digit minutes (with leading zeroes)<\/td>\n03<\/td>\n<\/tr>\n
    S<\/td>\n2-digit seconds (with leading zeroes)<\/td>\n18<\/td>\n<\/tr>\n
    L<\/td>\n3-digit milliseconds (with leading zeroes)<\/td>\n038<\/td>\n<\/tr>\n
    N<\/td>\n9-digit nanoseconds (with leading zeroes)<\/td>\n038000000<\/td>\n<\/tr>\n
    P<\/td>\nUppercase morning or afternoon marker<\/td>\nAM<\/td>\n<\/tr>\n
    p<\/td>\nLowercase morning or afternoon marker<\/td>\nam<\/td>\n<\/tr>\n
    z<\/td>\nRFC 822 numeric offset from GMT<\/td>\n-0600<\/td>\n<\/tr>\n
    Z<\/td>\nTime zone<\/td>\nPST<\/td>\n<\/tr>\n
    s<\/td>\nSeconds since 1970-01-01 00:00:00 GMT<\/td>\n2078861332<\/td>\n<\/tr>\n
    Q<\/td>\nMilliseconds since 1970-01-01 00:00:00 GMT<\/td>\n20788613328374<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
    Table 1.0: Date and Time Conversion Codes<\/p>\n
     <\/p>\n
     <\/p>\n
    3. Converting Strings to Dates<\/strong><\/h4>\n
    You can convert dates to string using the parsed() method. This method is provided by the SimpleDateFormat class. So the parse() method attempts to convert a string data to date data.<\/p>\n
    The code in Listing 1.1 demonstrates this.<\/p>\n
     <\/p>\n
    import<\/span> java.text.ParseException<\/span>;<\/span>\r\nimport<\/span> java.text.SimpleDateFormat<\/span>;<\/span>\r\nimport<\/span> java.util.Date<\/span>;<\/span>\r\nimport<\/span> java.util.Scanner<\/span>;<\/span>\r\n\r\npublic<\/span> class<\/span> DateDemo<\/span> {<\/span>\r\n\r\n\tpublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String[]<\/span> args)<\/span> {<\/span>\r\n\t\t\t\r\n\t\t\/\/Create a new SimpleDateFormat<\/span>\r\n\t\tSimpleDateFormat ft =<\/span> new<\/span> SimpleDateFormat(<\/span>\"yyyy-MM-dd\"<\/span>);<\/span>\r\n\t\t\r\n\t\t\/\/Get a new date from input<\/span>\r\n\t\tScanner scanner =<\/span> new<\/span> Scanner(<\/span>System.<\/span>in<\/span>);<\/span>\r\n\t\tSystem.<\/span>out<\/span>.<\/span>print<\/span>(<\/span>\"Please enter a date: \"<\/span>);<\/span>\r\n\t\tString strDate =<\/span> scanner.<\/span>nextLine<\/span>();<\/span>\r\n\t\t\r\n\t\ttry<\/span> {<\/span>\r\n\t\t\t\/\/Parse the string into a date<\/span>\r\n\t\t\tDate dtDate =<\/span> ft.<\/span>parse<\/span>(<\/span>strDate);<\/span>\r\n\t\t\tSystem.<\/span>out<\/span>.<\/span>println<\/span>(<\/span>\"You entered \"<\/span> +<\/span> dtDate);<\/span>\r\n\t\t}<\/span> catch<\/span> (<\/span>ParseException e)<\/span> {<\/span>\r\n\t\t\tSystem.<\/span>out<\/span>.<\/span>println<\/span>(<\/span>\"Unable to convert to date\"<\/span> +<\/span> ft);<\/span>\r\n\t\t\te.<\/span>printStackTrace<\/span>();<\/span>\r\n\t\t}<\/span>\t\t\t\t\r\n\t}<\/span>\r\n}<\/span>\r\n<\/pre>\n
    Listing 1.1: Converting a String to a Data<\/p>\n
     <\/p>\n
     <\/p>\n
    4. Sleeping for some Time<\/strong><\/h4>\n
    You will be able to delay for a period of time. This time is specified in milliseconds. But to do this, you need to use a the sleep method from the Thread class<\/p>\n
    For example, the code below makes the program sleep for 2000 miliseconds (2 seconds)<\/p>\n
     <\/p>\n
    import<\/span> java.util.Date<\/span>;<\/span>\r\n\r\npublic<\/span> class<\/span> DateSleepDemo<\/span> {<\/span>\r\n\tpublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String args[])<\/span> {<\/span>\r\n\t\t\r\n\t\ttry<\/span> {<\/span>\r\n\t\t\t\/\/Print current date<\/span>\r\n\t\t\tSystem.<\/span>out<\/span>.<\/span>print<\/span>(<\/span>new<\/span> Date()<\/span> +<\/span> \"\\n\"<\/span>);<\/span>\r\n\t\t\t\r\n\t\t\t\/\/Sleep for 2 seconds<\/span>\r\n\t\t\tThread.<\/span>sleep<\/span>(<\/span>2000<\/span>);<\/span>\t\t\t\r\n\t\t\t\r\n\t\t\t\/\/Print current date after the sleep<\/span>\r\n\t\t\tSystem.<\/span>out<\/span>.<\/span>print<\/span>(<\/span>new<\/span> Date());<\/span>\r\n\t\t\t\r\n\t\t}<\/span> catch<\/span> (<\/span>InterruptedException e)<\/span> {<\/span>\r\n\t\t\tSystem.<\/span>out<\/span>.<\/span>println<\/span>(<\/span>\"Error occured: \"<\/span>);<\/span>\r\n\t\t\te.<\/span>printStackTrace<\/span>();<\/span>\r\n\t\t}<\/span>\t\t\r\n\t}<\/span>\r\n}\r\n<\/span><\/pre>\n
    Listing 1.2: Sleeping for a time<\/p>\n
     <\/p>\n
    If you run the code above, you will have this result:<\/p>\n
    <\/p>\n
    Sat Jan 19<\/span> 13<\/span>:<\/span>20<\/span>:<\/span>19<\/span> CET 2019<\/span>\r\nSat Jan 19<\/span> 13<\/span>:<\/span>20<\/span>:<\/span>22<\/span> CET 2019<\/span>\r\n<\/pre>\n
    Note the the sleep code is surrounded by a try\/catch block. This is because its possible for error to occur when working with threads<\/p>\n
     <\/p>\n
    5. How to get Elapsed Time<\/strong><\/h4>\n
    Although the above code gives use the elapsed time, there is method used to get the real milliseconds that actually elapsed.<\/p>\n
    This method is currentTimeMIllis. So instead of using new Date(), we use System.currentTimeMillis().<\/p>\n
    The code below illustrates this.<\/p>\n
     <\/p>\n
    import<\/span> java.util.Date<\/span>;<\/span>\r\n\r\npublic<\/span> class<\/span> ElapsedTimeDemo<\/span> {<\/span>\r\n\r\n\tpublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String[]<\/span> args)<\/span> {<\/span>\r\n\t\tlong<\/span> begin =<\/span> System.<\/span>currentTimeMillis<\/span>();<\/span>\r\n\t\tSystem.<\/span>out<\/span>.<\/span>println<\/span>(<\/span>new<\/span> Date()<\/span> +<\/span> \"\\n\"<\/span>);<\/span>\r\n\t\t\r\n\t\ttry<\/span> {<\/span>\r\n\t\t\tThread.<\/span>sleep<\/span>(<\/span>5000<\/span>);<\/span>\r\n\t\t\tSystem.<\/span>out<\/span>.<\/span>println<\/span>(<\/span>new<\/span> Date()<\/span> +<\/span> \"\\n\"<\/span>);<\/span>\r\n\t\t\t\r\n\t\t\tlong<\/span> end =<\/span> System.<\/span>currentTimeMillis<\/span>();<\/span>\r\n\t\t\tlong<\/span> elapsed =<\/span> end -<\/span> begin;<\/span>\r\n\t\t\t\r\n\t\t\tSystem.<\/span>out<\/span>.<\/span>println<\/span>(<\/span>\"Elapsed time is \"<\/span> +<\/span> elapsed);<\/span>\r\n\t\t}<\/span> catch<\/span> (<\/span>InterruptedException e)<\/span> {<\/span>\r\n\t\t\tSystem.<\/span>out<\/span>.<\/span>println<\/span>(<\/span>\"Error occured: \"<\/span>);<\/span>\r\n\t\t\te.<\/span>printStackTrace<\/span>();<\/span>\r\n\t\t}<\/span>\r\n\t\t\r\n\t\t\r\n\t}<\/span>\r\n\r\n}<\/span>\r\n<\/pre>\n
    Listing 1.3: Measuring elapsed time.<\/p>\n
     <\/p>\n
    If you run the code in Listing 1.3 above, you will get the output:<\/p>\n
     <\/p>\n
    <\/p>\n
    Sat Jan 19<\/span> 13<\/span>:<\/span>39<\/span>:<\/span>53<\/span> CET 2019<\/span>\r\n\r\nSat Jan 19<\/span> 13<\/span>:<\/span>39<\/span>:<\/span>58<\/span> CET 2019<\/span>\r\n\r\nElapsed time is 5028<\/span>\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"
    So we would just continue with Date and Time. You can review Date and Time Part 1 if you have not.   In this tutorial, … <\/p>\n","protected":false},"author":395,"featured_media":120,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[2],"tags":[],"class_list":["post-119","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-java-tutorial"],"_links":{"self":[{"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/posts\/119","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/users\/395"}],"replies":[{"embeddable":true,"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/comments?post=119"}],"version-history":[{"count":5,"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/posts\/119\/revisions"}],"predecessor-version":[{"id":209,"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/posts\/119\/revisions\/209"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/media\/120"}],"wp:attachment":[{"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/media?parent=119"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/categories?post=119"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/tags?post=119"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}