Time operations for Java calendar classes __java

The time operation of the Java Calendar class, which may be the simplest scenario for creating and managing calendars and operating times in a Java environment, and the demo code is simple.

Shows the time of acquisition, the cumulative and exhausting of datetime, and the comparison of date and time.

Original address: blog.csdn.net/joyous/article/details/9630893

Precautions:

The month of the Calendar starts from 0, which is the 12 months of the year from 0 ~ 11.

The Calendar.day_of_week definition values are as follows, starting every week from SUNDAY, from 1 ~ 7:

Calendar.sunday = 1
Calendar.monday = 2
Calendar.tuesday = 3
Calendar.wednesday = 4
Calendar.thursday = 5
Calendar.friday = 6
Calendar.saturday = 7

format definition for SimpleDateFormat

Letter

	Date or Time Component	Presentation	examples
G	Era designator	Text	AD
Y	Year	Year	1996; 96
Y	Week year	Year	2009; 09
M	Month in [context sensitive]	Month	July; June June; 07
L	Month in year (standalone form)	Month	July; June June; 07
W	Week in the Year	Number	27
W	Week in month	Number	2
D	Day in year	Number	189
D	Day in month	Number	10
F	Day of week in month	Number	2
E	Day name in week	Text	Tuesday; Tue
U	Day number of week (1 = Monday, ..., 7 = Sunday)	Number	1
A	AM/PM Marker	Text	Pm
H	Hour in Day (0-23)	Number	0
K	Hour in Day (1-24)	Number	24
K	Hour in AM/PM (0-11)	Number	0
H	Hour in AM/PM (1-12)	Number	12
M	Minute in Hour	Number	30
S	Second in minute	Number	55
S	Millisecond	Number	978
Z	Time zone	General Time Zone	Pacific Standard time; PST; gmt-08:00
Z	Time zone	RFC 822 Time Zone	-0800
X	Time zone	ISO 8601 time Zone	-08; -0800; -08:00

The Java Calendar demo code is as follows:

Package demo;
Import Java.util.Date;
Import Java.text.SimpleDateFormat;
Import Java.text.DateFormat;
Import java.text.ParseException;

Import Java.util.Calendar; public class Test {public Test () {} public static void Main (string[] args) {//String conversion date format//Dateform
    At fmtdatetime = new SimpleDateFormat ("Yyyy-mm-dd HH:mm:ss");
    Receive incoming parameter//String strdate = args[1];

    Gets the date format object//Dates date = Fmtdatetime.parse (strdate);
    Full display today's date time String str = (new SimpleDateFormat ("Yyyy-mm-dd HH:mm:ss:SSS")). Format (new date ());

    System.out.println (str);

    Create Calendar Object Calendar calendar = Calendar.getinstance (); try {//Set the time for the Calendar method//sets the time format passed in SimpleDateFormat DateFormat = new SimpleDateFormat ("yyyy-m-
      D h:m:s ");
      Specify a date = Dateformat.parse ("2013-6-1 13:24:16");

      The date calendar.settime (date) to which calendar is set to date; Displays the time that has just been set in a specific format str = (new SimpleDateFormat ("yyYY-MM-DD HH:mm:ss:SSS ")). Format (Calendar.gettime ());
    System.out.println (str);
    catch (ParseException e) {e.printstacktrace (); //or another set of calendar methods//To be divided into year, month, date, hourofday, minute, second calendar = Calendar.getinstance (
    );
    Calendar.set (2013, 1, 2, 17, 35, 44);
    str = (new SimpleDateFormat ("Yyyy-mm-dd HH:mm:ss:SSS")). Format (Calendar.gettime ());

    System.out.println (str);
    Calendar to get the method of the current time//Initialize (reset) Calendar Object calendar = Calendar.getinstance ();

    or use date to initialize the Calendar object Calendar.settime (new Date ());
    SetTime similar to the line above//Date date = new Date ();

    Calendar.settime (date);
    str = (new SimpleDateFormat ("Yyyy-mm-dd HH:mm:ss:SSS")). Format (Calendar.gettime ());

    System.out.println (str);
    Show year int = Calendar.get (calendar.year);

    System.out.println ("Year are =" + string.valueof (year));
   Displays the month (starting from 0, the actual display to add one) int month = Calendar.get (calendar.month); System.out.println ("Nth is =" + (month + 1));
    This week a few int week = Calendar.get (Calendar.day_of_week);

    SYSTEM.OUT.PRINTLN ("Week is =" + week);
    This year's nth day int day_of_year = Calendar.get (calendar.day_of_year);

    System.out.println ("day_of_year is =" + day_of_year);
    This month the nth day int day_of_month = Calendar.get (calendar.day_of_month);

    System.out.println ("Day_of_month =" + string.valueof (day_of_month));
    3 hours later Calendar.add (Calendar.hour_of_day, 3);
    int hour_of_day = Calendar.get (Calendar.hour_of_day);

    System.out.println ("Hour_of_day + 3 =" + Hour_of_day);
    The current number of minutes int MINUTE = Calendar.get (Calendar.minute);

    System.out.println ("MINUTE =" + MINUTE);
    15 minutes later Calendar.add (Calendar.minute, 15);
    MINUTE = Calendar.get (Calendar.minute);

    System.out.println ("MINUTE + =" + MINUTE);
    30 minutes ago Calendar.add (Calendar.minute,-30);
    MINUTE = Calendar.get (Calendar.minute); System.out.println ("MinutE-30 = "+ MINUTE);
    Format shows str = (new SimpleDateFormat ("Yyyy-mm-dd HH:mm:ss:SS")). Format (Calendar.gettime ());

    System.out.println (str);
    Reset Calendar Displays the current time Calendar.settime (new Date ());
    str = (new SimpleDateFormat ("Yyyy-mm-dd HH:mm:ss:SS")). Format (Calendar.gettime ());

    System.out.println (str);

    Create a calendar to compare time calendar calendarnew = Calendar.getinstance ();
    Set to 5 hours ago, the latter large, display-1 Calendarnew.add (Calendar.hour,-5);

    System.out.println ("Time comparison:" + Calendarnew.compareto (calendar));
    Set 7 hours later, the former is large, showing 1 calendarnew.add (Calendar.hour, +7);

    System.out.println ("Time comparison:" + Calendarnew.compareto (calendar));
    Return 2 hours, same time, show 0 calendarnew.add (Calendar.hour,-2);
  System.out.println ("Time comparison:" + Calendarnew.compareto (calendar)); }
}

Run results

2013-06-07 23:27:34:195
2013-06-01 13:24:16:000
2013-02-02
17:35:44:197 2013-06-07 23:27:34:197 Year is = 2013
nth are = 6
Week is = 6
day_of_year is = 158
Day_of_month = 7
hour_of_day + 3 = 2
MI Nute =
MINUTE + =
MINUTE-30 =
2013-06-08 02:12:34:197 2013-06-07
Time comparison: -1
Time Comparison: 1
time comparison: 0

To calculate the time difference, the Calendar.gettimeinmillis () can be used to obtain two times the microsecond interval, and then be converted, such as to obtain the number of days, the code is as follows:

    Microsecond time difference
    long val = Calendarend.gettimeinmillis ()-Calendarbegin.gettimeinmillis ();
    The conversion gets the number of days
    long day = val/(1000 * 60 * 60 * 24);

Original address: blog.csdn.net/joyous/article/details/9630893

http://blog.csdn.net/joyous/article/details/9630893

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