Date Class :

 Date Class :

·        The Date class is a predefined class in Java.

·        It can be used to get the current system date and time.

·        To use the Date class, import the java.util package.

 

package DateBasics;

import java.util.Date;

public class DateBasics1 {

               public static void main(String[] args) {

                              //Create obj for Date class

                              Date d = new Date();

                              // import java.util pkg

                              System.out.println("Date =" + d);

                              // Date =Thu May 02 08:29:52 IST 2024

                              //  get  date

                              int dd = d.getDate();

                              System.out.println("dd= "+ dd);// dd= 2

                              // get month

                              int mm = d.getMonth();

                              System.out.println("mm="+ mm);// mm=4   actual month-1 May = 5  th month = 5-1 =4

                              // display actualMonth

                              mm = mm +1;

                              //    4+1

                              //    5

                              System.out.println("actualMonth="+mm);// actualMonth=5

                              // get year

                              int yy = d.getYear();

                              //          124  // 2024

                              //                -  124

                              ///-----------------------------

                              //                  1900

                              System.out.println("yy="+ yy);// expecting -2024 //actual = yy=124 **Care

                              // actual year  = 

                              int actualYear =  yy + 1900;

                              //               124 +  1900

                              //            2024

                              //  actualYear=  2024     

                              System.out.println("actualYear ="+actualYear);

                              // 1900

                              //  2024

                              //   124

                              //  1900

                              // // date =Date =Fri May 19 08:51:24 IST 2023

                              //HW get hours               

                              // HW get minutes

                              //HW get seconds

               }

}

o/p:

Date =Thu May 02 08:37:12 IST 2024

dd= 2

mm=4

actualMonth=5

yy=124

actualYear =2024

                

SimpleDateFomat Basics:           

·        SimpleDateFormat is a predefined class in Java.

·        It can be used to display given date in diff formats

                              // date =Fri Jan 13 09:39:15 IST 2023

                              //     dd-MM/yyyy  ,   MM--dd-yyyy,   yyyy-MM-dd

                              // MM -  Months

·        It can be used to format and parse dates into various formats.

 

package DateBasics;

import java.text.SimpleDateFormat;

import java.util.Date;

public class SimpleDateFromatBasics1 {

               public static void main(String[] args) {

                              // display date in format - dd-MM-yyyy

//                           create obj for SimpleDateFormat class and pass diff formats

                              SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");

                              // import java.text.SimpleDateFormat;

                             

                              //create obj for Date class

                              Date d  = new Date();

                              // import java.util.Date;

                              System.out.println("d="+ d);//                   d=Thu May 02 08:43:16 IST 2024

                              //format date  and dispay

                                                            //   format()  can be used to convert Date class obj to String value

                              String ddMMyyyy = sdf.format(d);

                              //                 //  02-05-2024

                              ////  dd-MM-yyyy

                              System.out.println("ddMMyyyy="+ ddMMyyyy);

//                                                         ddMMyyyy= 02-05-2024

                              //  disply date in  MM--dd-yyyy,   05-02-2024

                             

                              // format and display

                              sdf = new SimpleDateFormat("MM-dd-yyyy");

                             

                               // d=Fri May 19 09:09:27 IST 2023

                              //   format()  can be used to convert Date class obj to String value

                              String MMddyyy = sdf.format(d);

                              //                 05-02-2024

                               System.out.println("MMddyyy="+MMddyyy);// 05-02-2024

                             

                              // HW   display date in yyyy-MM-dd

                              // HW  display date in dd/MM/yyyy

                               

//                           HW  display date in dd:MM:yyyy

                              // display date in  mm-dd-yyyy  -//   mm - minutes MM- Month

                               // 08:48:50  hh:mm:ss MM-Month

                               

                               sdf = new SimpleDateFormat("mm-dd-yyyy");

                               String mmddyyyy = sdf.format(d);

                               

                               System.out.println("mmddyyyy ="+mmddyyyy); // mmddyyyy = 50-02-2024

                               //  50  respresents minutes

                               

                              //HW display date in format  -MMM-dd-yy  Jan, Feb

                              // HW Display get hour, min Seconds

                              //     hh:mm:s     

               }

}

Parse():

                              //Parse () can be used to convert String date  to Date class obj

               Converts a date string (e.g., "13-01-2023") into a Date object based on the specified format (e.g., dd-MM-yyyy).

 

package DateBasics;

import java.text.ParseException;

import java.text.SimpleDateFormat;

import java.util.Date;

public class SimpleDateFromatBasics2 {

               public static void main(String[] args) throws ParseException {

                              // create Date class obj

                              Date d = new Date();

                              // import java.util.Date;

                              System.out.println("date=" + d);// Thu May 02 08:53:24 IST 2024

                              // create obj for SimpleDateFormat -class and pass MMM-dd-yy

                              SimpleDateFormat sdf = new SimpleDateFormat("MMM-dd-yy");

                              String  MMddyyyy= sdf.format(d);

                              System.out.println("MMddyyyy ="+MMddyyyy);

                              //                         May-02-24         2024

                              //Parse () :    can be used to convert String date  to Date class obj

                              String sdate= "17/01/2023";

                              //                           String sdate= "01/17/2023"; // Dont pass the data in this format

                             

                              // throws ParseException

//                           Date d2 = sdf.parse(sdate);

//                                                                                       Date d2 =sdf.parse(sdate);            //Exception in thread "main" java.text.ParseException: Unparseable date: "17/01/2023"                                           

//                                                                                       System.out.println("d2 ="+d2);// d2 =

                             

                              //  if u pass any invalid data (String ) in parse, it throws ParseException: Unparseable date:

                              Date d3 = sdf.parse(MMddyyyy) ;// May-02-24

                              //          Thu May 02 00:00:00 IST 2024

                              //            

                              System.out.println("d3="+ d3);//d3=Thu May 02 00:00:00 IST 2024

               }

}

              

Calendar:

·        Calendar is a predefined class in Java.

·        It is a part of the java.util package.

·        Used to perform operations related to dates and times, including manipulating and retrieving calendar fields.

 

package DateBasics;

import java.util.Calendar;

import java.util.Date;

public class CalendarBasics {

               public static void main(String[] args) {

                              // Calendar:  predefined class in java

//                           Calendar cal = new Calendar();

                              //   Cannot instantiate the type Calendar

                              Calendar cal = Calendar.getInstance();

                             

                                                            System.out.println("Cal ="+cal);

                                                    //java.util.GregorianCalendar[time=1714621029594,areFieldsSet=true,areAllFieldsSet=true,

                                             //lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Calcutta",offset=19800000,dstSavings=0,

                                                            //useDaylight=false,transitions=7,lastRule=null],

                                                            //firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,

                                             //YEAR=2024,MONTH=4,WEEK_OF_YEAR=18,WEEK_OF_MONTH=1,DAY_OF_MONTH=2,DAY_OF_YEAR=123,

                                                         //DAY_OF_WEEK=5,DAY_OF_WEEK_IN_MONTH=1,AM_PM=0,HOUR=9,HOUR_OF_DAY=9

                                                            //,MINUTE=7,SECOND=9,MILLISECOND=594,ZONE_OFFSET=19800000,DST_OFFSET=0]

                                                            // get data and time  - getTime()

                                                            Date d = cal.getTime();

                                                            System.out.println("d="+ d); //d=Thu May 02 09:09:11 IST 2024

                                                            // //  add 2 days to current system data

                                                            cal.add(Calendar.DAY_OF_YEAR, 2);

//                                                         cal.add(Calendar.DAY_OF_MONTH, 2);

                                                            d = cal.getTime();

                                                            System.out.println("d=" + d);// d=Sat May 04 09:13:34 IST 2024

                                                           

                                                           

                                                            // add 2 months to current sys stem date

                                                            cal.add(Calendar.MONTH, 2);

                                                            d = cal.getTime();

                                                            System.out.println("d="+d);

                                                            // d1=d=d=Tue Jul 02 09:17:49 IST 2024

                                                            //  HW  add 3 years to current system date

                                                            cal.add(Calendar.YEAR, 3);

                                                            d = cal.getTime();

                                                            System.out.println("d="+d);// d=Fri Jul 02 09:19:01 IST 2027

                                                           

                                                            // substract  1 day from current sysstem date     

                                                            cal.add(Calendar.DAY_OF_MONTH, -1);

                                                            d = cal.getTime();

                                                            System.out.println("d="+d);

                                                            // d=

                                                            // HW  substact 2 month

                                                            // HW  Substract 3 years

               }

}

o/p:

Cal =java.util.GregorianCalendar[time=1714622143096,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Calcutta",offset=19800000,dstSavings=0,useDaylight=false,transitions=7,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2024,MONTH=4,WEEK_OF_YEAR=18,WEEK_OF_MONTH=1,DAY_OF_MONTH=2,DAY_OF_YEAR=123,DAY_OF_WEEK=5,DAY_OF_WEEK_IN_MONTH=1,AM_PM=0,HOUR=9,HOUR_OF_DAY=9,MINUTE=25,SECOND=43,MILLISECOND=96,ZONE_OFFSET=19800000,DST_OFFSET=0]

d=Thu May 02 09:25:43 IST 2024

d=Sat May 04 09:25:43 IST 2024

d=Thu Jul 04 09:25:43 IST 2024

d=Sun Jul 04 09:25:43 IST 2027

d=Sat Jul 03 09:25:43 IST 2027