JAVA TUTORIALS - Java - Date & Time
Java - Date & Time
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SN | Methods with Description |
---|---|
1 | boolean after(Date date) Returns true if the invoking Date object contains a date that is later than the one specified by date, otherwise, it returns false. |
2 | boolean before(Date date) Returns true if the invoking Date object contains a date that is earlier than the one specified by date, otherwise, it returns false. |
3 | Object clone( ) Duplicates the invoking Date object. |
4 | int compareTo(Date date) Compares the value of the invoking object with that of date. Returns 0 if the values are equal. Returns a negative value if the invoking object is earlier than date. Returns a positive value if the invoking object is later than date. |
5 | int compareTo(Object obj) Operates identically to compareTo(Date) if obj is of class Date. Otherwise, it throws a ClassCastException. |
6 | boolean equals(Object date) Returns true if the invoking Date object contains the same time and date as the one specified by date, otherwise, it returns false. |
7 | long getTime( ) Returns the number of milliseconds that have elapsed since January 1, 1970. |
8 | int hashCode( ) Returns a hash code for the invoking object. |
9 | void setTime(long time) Sets the time and date as specified by time, which represents an elapsed time in milliseconds from midnight, January 1, 1970 |
10 | String toString( ) Converts the invoking Date object into a string and returns the result. |
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Simple DateFormat format codes:
Character | Description | Example |
---|---|---|
G | Era designator | AD |
y | Year in four digits | 2001 |
M | Month in year | July or 07 |
d | Day in month | 10 |
h | Hour in A.M./P.M. (1~12) | 12 |
H | Hour in day (0~23) | 22 |
m | Minute in hour | 30 |
s | Second in minute | 55 |
S | Millisecond | 234 |
E | Day in week | Tuesday |
D | Day in year | 360 |
F | Day of week in month | 2 (second Wed. in July) |
w | Week in year | 40 |
W | Week in month | 1 |
a | A.M./P.M. marker | PM |
k | Hour in day (1~24) | 24 |
K | Hour in A.M./P.M. (0~11) | 10 |
z | Time zone | Eastern Standard Time |
' | Escape for text | Delimiter |
" | Single quote | ` |
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Date and Time Conversion Characters:
Character | Description | Example |
---|---|---|
c | Complete date and time | Mon May 04 09:51:52 CDT 2009 |
F | ISO 8601 date | 2004-02-09 |
D | U.S. formatted date (month/day/year) | 02/09/2004 |
T | 24-hour time | 18:05:19 |
r | 12-hour time | 06:05:19 pm |
R | 24-hour time, no seconds | 18:05 |
Y | Four-digit year (with leading zeroes) | 2004 |
y | Last two digits of the year (with leading zeroes) | 04 |
C | First two digits of the year (with leading zeroes) | 20 |
B | Full month name | February |
b | Abbreviated month name | Feb |
m | Two-digit month (with leading zeroes) | 02 |
d | Two-digit day (with leading zeroes) | 03 |
e | Two-digit day (without leading zeroes) | 9 |
A | Full weekday name | Monday |
a | Abbreviated weekday name | Mon |
j | Three-digit day of year (with leading zeroes) | 069 |
H | Two-digit hour (with leading zeroes), between 00 and 23 | 18 |
k | Two-digit hour (without leading zeroes), between 0 and 23 | 18 |
I | Two-digit hour (with leading zeroes), between 01 and 12 | 06 |
l | Two-digit hour (without leading zeroes), between 1 and 12 | 6 |
M | Two-digit minutes (with leading zeroes) | 05 |
S | Two-digit seconds (with leading zeroes) | 19 |
L | Three-digit milliseconds (with leading zeroes) | 047 |
N | Nine-digit nanoseconds (with leading zeroes) | 047000000 |
P | Uppercase morning or afternoon marker | PM |
p | Lowercase morning or afternoon marker | pm |
z | RFC 822 numeric offset from GMT | -0800 |
Z | Time zone | PST |
s | Seconds since 1970-01-01 00:00:00 GMT | 1078884319 |
Q | Milliseconds since 1970-01-01 00:00:00 GMT | 1078884319047 |
GregorianCalendar Class:
SN | Constructor with Description |
---|---|
1 | GregorianCalendar() Constructs a default GregorianCalendar using the current time in the default time zone with the default locale. |
2 | GregorianCalendar(int year, int month, int date) Constructs a GregorianCalendar with the given date set in the default time zone with the default locale. |
3 | GregorianCalendar(int year, int month, int date, int hour, int minute) Constructs a GregorianCalendar with the given date and time set for the default time zone with the default locale. |
4 | GregorianCalendar(int year, int month, int date, int hour, int minute, int second) Constructs a GregorianCalendar with the given date and time set for the default time zone with the default locale. |
5 | GregorianCalendar(Locale aLocale) Constructs a GregorianCalendar based on the current time in the default time zone with the given locale. |
6 | GregorianCalendar(TimeZone zone) Constructs a GregorianCalendar based on the current time in the given time zone with the default locale. |
7 | GregorianCalendar(TimeZone zone, Locale aLocale) Constructs a GregorianCalendar based on the current time in the given time zone with the given locale. |
SN | Methods with Description |
---|---|
1 | void add(int field, int amount) Adds the specified (signed) amount of time to the given time field, based on the calendar's rules. |
2 | protected void computeFields() Converts UTC as milliseconds to time field values. |
3 | protected void computeTime() Overrides Calendar Converts time field values to UTC as milliseconds. |
4 | boolean equals(Object obj) Compares this GregorianCalendar to an object reference. |
5 | int get(int field) Gets the value for a given time field. |
6 | int getActualMaximum(int field) Return the maximum value that this field could have, given the current date. |
7 | int getActualMinimum(int field) Return the minimum value that this field could have, given the current date. |
8 | int getGreatestMinimum(int field) Returns highest minimum value for the given field if varies. |
9 | Date getGregorianChange() Gets the Gregorian Calendar change date. |
10 | int getLeastMaximum(int field) Returns lowest maximum value for the given field if varies. |
11 | int getMaximum(int field) Returns maximum value for the given field. |
12 | Date getTime() Gets this Calendar's current time. |
13 | long getTimeInMillis() Gets this Calendar's current time as a long. |
14 | TimeZone getTimeZone() Gets the time zone. |
15 | int getMinimum(int field) Returns minimum value for the given field. |
16 | int hashCode() Override hashCode. |
17 | boolean isLeapYear(int year) Determines if the given year is a leap year. |
18 | void roll(int field, boolean up) Adds or subtracts (up/down) a single unit of time on the given time field without changing larger fields. |
19 | void set(int field, int value) Sets the time field with the given value. |
20 | void set(int year, int month, int date) Sets the values for the fields year, month, and date. |
21 | void set(int year, int month, int date, int hour, int minute) Sets the values for the fields year, month, date, hour, and minute. |
22 | void set(int year, int month, int date, int hour, int minute, int second) Sets the values for the fields year, month, date, hour, minute, and second. |
23 | void setGregorianChange(Date date) Sets the GregorianCalendar change date. |
24 | void setTime(Date date) Sets this Calendar's current time with the given Date. |
25 | void setTimeInMillis(long millis) Sets this Calendar's current time from the given long value. |
26 | void setTimeZone(TimeZone value) Sets the time zone with the given time zone value. |
27 | String toString() Return a string representation of this calendar. |
Date( )
Date(long millisec)Getting Current Date & Time
import java.util.Date; public class DateDemo { public static void main(String args[]) { // Instantiate a Date object Date date = new Date(); // display time and date using toString() System.out.println(date.toString()); } }
Mon May 04 09:51:52 CDT 2009Date Formatting using SimpleDateFormat:
import java.util.*; import java.text.*; public class DateDemo { public static void main(String args[]) { Date dNow = new Date( ); SimpleDateFormat ft = new SimpleDateFormat ("E yyyy.MM.dd 'at' hh:mm:ss a zzz"); System.out.println("Current Date: " + ft.format(dNow)); } }
Current Date: Sun 2004.07.18 at 04:14:09 PM PDTDate Formatting using printf:
import java.util.Date; public class DateDemo { public static void main(String args[]) { // Instantiate a Date object Date date = new Date(); // display time and date using toString() String str = String.format("Current Date/Time : %tc", date ); System.out.printf(str); } }
Current Date/Time : Sat Dec 15 16:37:57 MST 2012
import java.util.Date; public class DateDemo { public static void main(String args[]) { // Instantiate a Date object Date date = new Date(); // display time and date using toString() System.out.printf("%1$s %2$tB %2$td, %2$tY", "Due date:", date); } }
Due date: February 09, 2004
import java.util.Date; public class DateDemo { public static void main(String args[]) { // Instantiate a Date object Date date = new Date(); // display formatted date System.out.printf("%s %tB %<te, %<tY", "Due date:", date); } }
Due date: February 09, 2004Parsing Strings into Dates:
import java.util.*; import java.text.*; public class DateDemo { public static void main(String args[]) { SimpleDateFormat ft = new SimpleDateFormat ("yyyy-MM-dd"); String input = args.length == 0 ? "1818-11-11" : args[0]; System.out.print(input + " Parses as "); Date t; try { t = ft.parse(input); System.out.println(t); } catch (ParseException e) { System.out.println("Unparseable using " + ft); } } }
$ java DateDemo 1818-11-11 Parses as Wed Nov 11 00:00:00 GMT 1818 $ java DateDemo 2007-12-01 2007-12-01 Parses as Sat Dec 01 00:00:00 GMT 2007Sleeping for a While:
import java.util.*; public class SleepDemo { public static void main(String args[]) { try { System.out.println(new Date( ) + "\n"); Thread.sleep(5*60*10); System.out.println(new Date( ) + "\n"); } catch (Exception e) { System.out.println("Got an exception!"); } } }
Sun May 03 18:04:41 GMT 2009 Sun May 03 18:04:51 GMT 2009Measuring Elapsed Time:
import java.util.*; public class DiffDemo { public static void main(String args[]) { try { long start = System.currentTimeMillis( ); System.out.println(new Date( ) + "\n"); Thread.sleep(5*60*10); System.out.println(new Date( ) + "\n"); long end = System.currentTimeMillis( ); long diff = end - start; System.out.println("Difference is : " + diff); } catch (Exception e) { System.out.println("Got an exception!"); } } }
Sun May 03 18:16:51 GMT 2009 Sun May 03 18:16:57 GMT 2009 Difference is : 5993Example:
import java.util.*; public class GregorianCalendarDemo { public static void main(String args[]) { String months[] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"}; int year; // Create a Gregorian calendar initialized // with the current date and time in the // default locale and timezone. GregorianCalendar gcalendar = new GregorianCalendar(); // Display current time and date information. System.out.print("Date: "); System.out.print(months[gcalendar.get(Calendar.MONTH)]); System.out.print(" " + gcalendar.get(Calendar.DATE) + " "); System.out.println(year = gcalendar.get(Calendar.YEAR)); System.out.print("Time: "); System.out.print(gcalendar.get(Calendar.HOUR) + ":"); System.out.print(gcalendar.get(Calendar.MINUTE) + ":"); System.out.println(gcalendar.get(Calendar.SECOND)); // Test if the current year is a leap year if(gcalendar.isLeapYear(year)) { System.out.println("The current year is a leap year"); } else { System.out.println("The current year is not a leap year"); } } }
Date: Apr 22 2009 Time: 11:25:27 The current year is not a leap year