17 Examples Of Calendar Too Appointment Inward Java

The java.util.Calendar cast was added inwards Java on JDK 1.4 inwards an endeavor to create roughly flaws of the java.util.Date class. It did brand roughly chore simpler, e.g. create an arbitrary appointment comes easier using new GregorianCalendar(2016, Calendar.JUNE, 11) constructor, equally opposed to Date cast where the twelvemonth starts from 1900 in addition to Month was starting from zero. It didn't solve all the problems e.g. mutability in addition to thread-safety of Date cast notwithstanding remains, but it does brand life easier at that time. Now amongst Java 8 everything related to Date in addition to Time has acquire super slow in addition to consistent but unfortunately, it volition bring roughly other v to 10 years earlier older version of Java goes away. Don't believe me, at that topographic point are notwithstanding applications running on JDK 1.5 which was released 12 years ago. The bottom employment is it's notwithstanding of import to know well-nigh Date in addition to Calendar inwards Java.

The java.util.Calendar cast is an abstract class in addition to y'all obtain the event of a Calendar local to your timezone in addition to Locale yesteryear calling the getInstance() method of java.util.Calendar class. This method mostly returns an event of GregorianCalendar cast except when your JVM is running amongst Japanese in addition to Thai Locale where it returns dissimilar instances of Calendar e.g. BuddhistCalendar for Thai ("th_TH") in addition to JapaneseImperialCalendar for Japanese ("ja_JP") Locale.



The Gregorian calendar is the calendar which is used today. It came into resultant on Oct 15, 1582, inwards roughly countries in addition to afterwards inwards other countries. It replaces its predecessor the Julian calendar in addition to 10 days were removed from the calendar, i.e., Oct 4, 1582 (Julian) was followed yesteryear Oct 15, 1582 (Gregorian) due to differences inwards how Julian in addition to GregorianCalendar calculates jump year.

In Julian calendar, every 4 years is a leap year. In the Gregorian calendar, a jump twelvemonth is a twelvemonth that is divisible yesteryear 4 but non divisible yesteryear 100, or it is divisible yesteryear 400, i.e., the Gregorian calendar omits century years which are non divisible yesteryear 400 (removing three jump years (or three days) for every 400 years). Furthermore, Julian calendar considers the starting fourth dimension solar daytime of the twelvemonth equally march 25th, instead of Jan 1st.

The Calendar cast provides back upwards for extracting appointment in addition to fourth dimension fields from a Date e.g. YEAR, MONTH, DAY_OF_MONTH, HOUR, MINUTE, SECOND, MILLISECOND; equally good equally manipulating these fields e.g. yesteryear adding in addition to subtracting days from a appointment in addition to calculating adjacent or previous day, calendar month or twelvemonth (see) etc. In this article, I'll portion roughly useful Calendar representative to sympathise how to utilization it for your daily appointment in addition to time-related operations.

How to convert Date to Calendar inwards Java

One of the starting fourth dimension matter a Java developer should know spell using Calendar is the conversion betwixt Date in addition to Calendar classes. Similar to how y'all converted Timestamp to Date, hither besides nosotros tin terminate utilization the getTime() in addition to setTime() method, albeit this fourth dimension they are from the java.util.Calendar class.

By default, when y'all acquire the Calendar it has today's date, to ready to whatsoever arbitrary appointment simply telephone band the Calendar.setTime(date), at i time y'all receive got the correct appointment ready to your calendar in addition to y'all tin terminate utilization the Calendar's get() in addition to add() method to extract dissimilar fields in addition to manipulate them equally good e.g. day, calendar month in addition to year.

Date date= new Date(); Calendar cal = Calendar.getInstance(); cal.setTime(date);

Similarly, to convert a java.util.Calendar dorsum to the java.util.Date simply telephone band the getTime() method of Calendar cast equally shown inwards the next example:

Date d = cal.getTime();

Super slow right? but exclusively if y'all know. It's non really obvious from API equally Calendar doesn't bring a Date value inwards the constructor in addition to the refer getTime() in addition to setTime() besides doesn't betoken that they render or bring a Date value. If y'all desire to larn to a greater extent than well-nigh Date in addition to Calendar classes inwards Java, I propose reading Core Java Volume 1 - Fundamentals yesteryear Cay S. Horstmann, i of the amend books to larn meat Java concepts.

How to extract day, calendar month in addition to other fields from Calendar

Once y'all ready the Date to Calendar class, y'all tin terminate utilization its diverse get() method to extract dissimilar fields e.g. Calendar.get(Calendar.DAY_OF_MONTH) to acquire the current day. Here is a listing of Calendar champaign y'all tin terminate utilization amongst get() in addition to add() method:

get(Calendar.DAY_OF_WEEK): returns 1 (Calendar.SUNDAY) to seven (Calendar.SATURDAY).
get(Calendar.YEAR): returns year
get(Calendar.MONTH): returns 0 (Calendar.JANUARY) to eleven (Calendar.DECEMBER).
get(Calendar.DAY_OF_MONTH), get(Calendar.DATE): 1 to 31
get(Calendar.HOUR_OF_DAY): 0 to 23
get(Calendar.MINUTE): 0 to 59
get(Calendar.SECOND): 0 to 59
get(Calendar.MILLISECOND): 0 to 999
get(Calendar.HOUR): 0 to 11, to survive used together amongst Calendar.AM_PM.
get(Calendar.AM_PM): returns 0 (Calendar.AM) or 1 (Calendar.PM).

This is really of import to know because i time y'all know that y'all tin terminate extract whatsoever appointment or time-related champaign from Calendar instance. The Java How to Program yesteryear Dietel in addition to Dietel besides receive got som to a greater extent than practical examples of accessing appointment in addition to time-related attributes from Calendar instance.

How to add together days, calendar month in addition to twelvemonth to Date

You tin terminate utilization the add() method of Calendar to add together or subtract a day, month, year, hour, a infinitesimal or whatsoever other champaign from Date inwards Java. Yes, the same method is used for adding in addition to subtracting, y'all simply postulate to locomote yesteryear a negative value for subtraction e.g. -1 to subtract i solar daytime in addition to acquire the yesterday's solar daytime equally shown inwards the next example:

cal2.add(Calendar.DAY_OF_MONTH, 1); d = cal2.getTime(); System.out.println("date after adding i solar daytime (tomorrow) : " + d);  cal2.add(Calendar.DAY_OF_MONTH, -2); d = cal2.getTime(); System.out.println("date after subtracting 2 solar daytime (yesterday) : " + d);  Output appointment after adding i solar daytime (tomorrow): quarta-feira Jun 22 00:00:00 IST 2016 appointment after subtracting 2 days (yesterday): Monday Jun 20 00:00:00 IST 2016

You tin terminate run across that the value of appointment returned yesteryear the Calendar is dissimilar after adding in addition to subtracting 2 days from calendar event using the add() method. Just remember, to subtract a day, locomote yesteryear a negative value e.g. to subtract 2 days nosotros passed -2. If y'all desire to subtract simply i day, locomote yesteryear -1

Java Calendar Example 

Here is our Java plan to demonstrate roughly to a greater extent than representative of Calendar cast inwards Java.

import java.util.Calendar; import java.util.Date; import java.util.GregorianCalendar;  /*  * Java Program to demo how to utilization Calendar to acquire a dissimilar appointment in addition to time-related attribute.  * This plan contains multiple how to create examples of Calendar cast to learn y'all how  * to acquire day, month, year, hour, infinitesimal or whatsoever other appointment in addition to fourth dimension realted attributes from  * Calendar instance.   */  public class Main {  public static void main(String[] args) {  Calendar cal = Calendar.getInstance(); // returns GregorianCalendar except Nippon in addition to Thailand  // Example 1 - acquire the twelvemonth from Calendar System.out.println("Year : " + cal.get(Calendar.YEAR));  // Example 2 - acquire the calendar month from Calendar System.out.println("Month : " + cal.get(Calendar.MONTH));  // Example three - acquire the Day of calendar month from Date in addition to Calendar System.out.println("Day of Month : " + cal.get(Calendar.DAY_OF_MONTH));  // Example 4 - acquire the Day of Week from Date System.out.println("Day of Week : " + cal.get(Calendar.DAY_OF_WEEK));  // Example v - acquire the Day of twelvemonth from Date System.out.println("Day of Year : " + cal.get(Calendar.DAY_OF_YEAR));  // Example half-dozen - acquire the Week of Year from Calendar System.out.println("Week of Year : " + cal.get(Calendar.WEEK_OF_YEAR));  // Example seven - acquire the Week of Month from Date System.out.println("Week of Month : " + cal.get(Calendar.WEEK_OF_MONTH));  // Example 8 - acquire the hr from time System.out.println("Hour : " + cal.get(Calendar.HOUR));  // Example nine - acquire the AM PM from time System.out.println("AM PM : " + cal.get(Calendar.AM_PM));  // Example 10 - acquire the hr of the solar daytime from Calendar System.out.println("Hour of the Day : " + cal.get(Calendar.HOUR_OF_DAY));  // Example eleven - acquire the infinitesimal from Calendar System.out.println("Minute : " + cal.get(Calendar.MINUTE));  // Example 12 - acquire the Second from Calendar System.out.println("Second : " + cal.get(Calendar.SECOND)); System.out.println();  // Example xiii - converting Date to Calendar Date date= new Date(); Calendar cal1 = Calendar.getInstance(); cal.setTime(date);  // Example fourteen - Creating GregorianCalendar of specific date Calendar cal2 = new GregorianCalendar(2016, Calendar.JUNE, 21);  // Example xv - Converting Calendar to Date Date d = cal2.getTime(); System.out.println("date from Calendar : " + d);  // Example xvi - adding 1 solar daytime into date cal2.add(Calendar.DAY_OF_MONTH, 1); d = cal2.getTime(); System.out.println("date after adding i solar daytime (tommorrow) : " + d);  // Example 17 - subtracting a solar daytime from day cal2.add(Calendar.DAY_OF_MONTH, -2); d = cal2.getTime(); System.out.println("date after subtracting 2 solar daytime (yesterday) : " + d); }  }  Output Year: 2016 Month: 5 Day of Month: 17 Day of Week: 6 Day of Year: 169 Week of Year: 25 Week of Month: 3 Hour: 4 AM PM: 1 Hour of the Day: 16 Minute: 24 Second: 37  appointment from Calendar : Tue Jun 21 00:00:00 SGT 2016 appointment after adding i solar daytime (tommorrow) : quarta-feira Jun 22 00:00:00 SGT 2016 appointment after subtracting 2 solar daytime (yesterday) : Monday Jun 20 00:00:00 SGT 2016

That's all well-nigh how to utilization Calendar cast inwards Java. It's a useful cast for extracting in addition to manipulating appointment in addition to time-related fields inwards Java half-dozen in addition to Java seven but amongst Java 8 it's value is diminished. You should exclusively utilization this cast if y'all are non running inwards Java 8. In Java 8 y'all should utilization the LocalDate methods to extract appointment related values, in addition to LocalTime's time-related methods to extract fourth dimension values e.g. hour, minutes in addition to seconds. You tin terminate besides read Java 8 inwards Action to larn to a greater extent than well-nigh novel Date in addition to Time API of Java 8.

Further Learning
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How to convert java.util.Date to java.sql.Date inwards JDBC? (tutorial) 

How to convert java.util.Date to java.time.LocalDateTime inwards Java 8? (tutorial)

Thanks for reading this article, if y'all similar this tutorial, delight portion amongst your friends in addition to colleagues. If y'all receive got whatsoever feedback or suggestions in addition to hence delight drib a comment. If y'all receive got whatsoever interesting example, which is non inwards this article, experience gratis to portion them amongst us. 

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