Java Tutorials
LocalDate represents only date, i.e year ,month,day
now()
method returns system's date.of
method returns specific date of your choice. Both are static methods.
LocalDate date = LocalDate.now();
LocalDate date =LocalDate.of(2020,11,11);
LocalDate date =LocalDate.of(2020,Month.OCTOBER,11);
System.out.println(date);
2020-11-11
LocalDate Object has instance methods to get Year,Month and Day.
getYear(), getDayOfMonth(),date.getDayOfWeek(), getMonth(), getMonthValue()
plusDays, plusWeeks, plusMonths, plusYears
Add Days
LocalDate date =LocalDate,of(2010,11,11);
System.out.println(date.plusDays(20););
2011-12-01
Add Months
LocalDate date =LocalDate,of(2010,11,11);
System.out.println(date.plusMonths(12));
2011-11-11
Add Years
LocalDate date =LocalDate,of(2010,11,11);
System.out.println(date.plusyears(21));
2032-11-11
System.out.println(date.plusyears(-21));
1990-11-11
LocalDate object implements Comparable
LocalDate date1 = LocalDate.of(2010,1,2);
LocalDate date2 = LocalDate.of(1990,1,2);
int value = date1.compareTo(date2); //20
date1 is greater than date2
int value = date2.compareTo(date1); //-20
date2 is less than date1
LocalDate objects can be compared with other LocalDate Object using following function, which returns boolean value.
LocalDate date1 = LocalDate.of(2010,1,2);
LocalDate date2 = LocalDate.of(1990,1,2);
date1.isEqual(date2); //false
date1.isAfter(date2); //true
date1.isBefore(date2); //false
LocalDate Object can be converted into a String, or String into a LocalDate Object using parse method.
Parse method has 2 variantsBoth are static methods, which can be accessed without using LocalDate Object instance.
String strDate = "1990-12-1"; LocalDate date = LocalDate.parse( strDate ); LocalDate Object is constructed. date.getYear() ; //1990 date.getMonthValue(); //12 date.getDayOfMonth(); //1
Use this method ,Date in any format.DateTimeFormatter class located in package java.time.format.DateTimeFormatter It is a general class to format Date and Time .
for ex: format of the Dates
12Aug2012
Aug122012
Feb1st2012
2022yearmonthOctDay1
to pase any of the above dates, programmer can use DateTimeFormatter class.
String strDate = "12Aug2012";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("ddMMMyyyy")
LocalDate date = LocalDate.parse( strDate, formatter );
LocalDate Object is constructed.
date.getYear() ; //2012
date.getMonthValue(); //8
date.getDayOfMonth(); //12
String strDate = "Feb1st2012";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MMMd'st'yyyy");
LocalDate date = LocalDate.parse( strDate, formatter );
//2012-02-01
Finding Months ,1st of the month falls on Sunday. In this example we Check every month's 1st is Sunday or Not.
LocalDate creates a Date for a specific year. datesUntil method generates stream of LocalDates from starting of the Year to end of the Year.
Filter condition checks is DayofMonth is 1 and DayOfWeek is SUNDAY, it returns TRUE only above condition is met, otherwise FALSE.
for YEAR 2023 , JANUARY and OCTOBER months Day 1st falls on SUNDAY
import java.time.*;
import java.util.stream.*;
LocalDate date = LocalDate.of(2023,1,1)
Stream<LocalDate> dates = date.datesUntil(LocalDate.of(2023,12,2))
dates.filter(d ->{return d.getDayOfMonth()==1 && d.getDayOfWeek().equals(DayOfWeek.SUNDAY);}).forEach(System.out::println)
2023-01-01
2023-10-01
public int get(TemporalField field)
TemporalField located in java.time.temporal package, which is used to query specified field in the locatedate object. If queried field is not valid , an exception is thrown, TemporalField is an interface, framework implemented class for this interface is ChronoField
LocalDate date = LocalDate.of(1992,7,12) date.get(ChronoField.YEAR) 1992 date.get(ChronoField.MONTH_OF_YEAR) 7 date.get(ChronoField.DAY_OF_MONTH) 12
LocalDate plus(long amountToAdd, TemporalUnit unit)
LocalDate plus(TemporalAmount amountToAdd)
TemporalUnit located in java.time.temporal package, Measurement of date & time is built on units, such as years,months,days etc., The instance of this interface represents the unit itself,rather than the amount of the unit.Framework implemented class for this interface is ChronoUnit.
TemporalAmount is an interface located in java.time.temporal package, This is an interface type for amount of time, like " 10yrs 3 months",framework implemented class for this interface is Duration and Period classes. Duration is based on time based object, Period is date based object
LocalDate date = LocalDate.of(1992,7,12) using TemporalUnit //Add 10 years to date System.out.println(date.plus(10,ChronoUnit.YEARS)) 2002-07-12 //Add 5 months System.out.println(date.plus(5,ChronoUnit.MONTHS)) 1997-12-12 //Add 13 days to LocalDate System.out.println(date.plus(13,ChronoUnit.DAYS)) 1997-07-25
TemporalAmount interface implemented by Period class, Which can be used to add specified amount of date as shown below. Period maintains Date related information, like years,months and days, and it has equivalent static methods, like ofYears, ofMonths,ofDays
LocalDate date = LocalDate.of(1992,7,12) using TemporalAmount implemented class Period //Add 10 years to date System.out.println(date.plus(Period.ofYears(10))) 2002-07-12 //Add 5 months System.out.println(date.plus(Period.ofMonths(5))) 1997-12-12 //Add 13 days to LocalDate System.out.println(date.plus(Period.ofDays(13)) 1997-07-25
R LocalDate.<R>query(TemporalQuery<R> query)
TemporalQuery located in java.time.temporal package, which is used to query specified field in the locatedate object. framework implemented class for this interface is TemporalQueries
TemporalQuery is a Functional Interface
LocalDate date = LocalDate.of(1992,7,12)
long LocalDate.until(Temporal endExclusive, TemporalUnit unit)
Temporal located in java.time.temporal package, All Date time classes implemented this interface. Until function takes 2 parameters, one is class which implemented Temporal interface, another one Class Which implemented TemporalUnit interface
Here we have LocalDate class implements temporal interface, ChronoUnit class implements TemporalUnit interface
LocalDate date = LocalDate.of(1992,7,12) System.out.println(date.until(LocalDate.of(1995,7,12), ChronoUnit.YEARS)+" Years") 3 Years System.out.println(date.until(LocalDate.of(1995,7,12), ChronoUnit.MONTHS)+" Months") 36 Months System.out.println(date.until(LocalDate.of(1995,7,12), ChronoUnit.DAYS)+" Days") 1095 Days
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