CODEWITHSUNDEEP
javadatecalendar
nanakondor
nanakondor

Reputation: 745

How to represent Date in java

I would like to have a simple Date class that has month, year, and day attributes.

I want a Date object to be included in a Magazine object so that I can know when was the Magazine published.

when I try using the Date object from Date class like shown below Date d1 = new Date (1,1,1); the Date from new Date was strikethrough showing that it is deprecated. I read about the new constructor replacing it but it looks very confusing. I dont understand how to accomplish this using Calendar class. If it is possible, I dont want to create my own Date class... Please help me. Thank you

Upvotes: 3

Views: 4862

Answers (2)

Basil Bourque
Basil Bourque

Reputation: 340230

tl;dr

I want a Date object to be included in a Magazine object so that I can know when was the Magazine published.

So add a member variable of type java.time.LocalDate. 

package work.basil.example;

import java.time.LocalDate;

public class Magazine
{
    // Member variables.
    public LocalDate published ;

    // Constructor.
    public Magazine ( LocalDate published )
    {
        this.published = published;
    }
}

To use it:

Magazine m = new Magazine( LocalDate.of( 2019 , Month.JANUARY , 23 ) ) ;

LocalDate

  • The modern approach uses LocalDate.
  • Never use java.util.Date or java.sql.Date.

The LocalDate class represents a date-only value without time-of-day and without time zone or offset-from-UTC.

A time zone is crucial in determining a date. For any given moment, the date varies around the globe by zone. For example, a few minutes after midnight in Paris France is a new day while still “yesterday” in Montréal Québec.

If no time zone is specified, the JVM implicitly applies its current default time zone. That default may change at any moment during runtime(!), so your results may vary. Better to specify your desired/expected time zone explicitly as an argument. If critical, confirm the zone with your user.

Specify a proper time zone name in the format of Continent/Region, such as America/Montreal, Africa/Casablanca, or Pacific/Auckland. Never use the 2-4 letter abbreviation such as EST or IST as they are not true time zones, not standardized, and not even unique(!). 

ZoneId z = ZoneId.of( "America/Montreal" ) ;  
LocalDate today = LocalDate.now( z ) ;

If you want to use the JVM’s current default time zone, ask for it and pass as an argument. If omitted, the code becomes ambiguous to read in that we do not know for certain if you intended to use the default or if you, like so many programmers, were unaware of the issue.

ZoneId z = ZoneId.systemDefault() ;  // Get JVM’s current default time zone.

Or specify a date. You may set the month by a number, with sane numbering 1-12 for January-December. 

LocalDate ld = LocalDate.of( 1986 , 2 , 23 ) ;  // Years use sane direct numbering (1986 means year 1986). Months use sane numbering, 1-12 for January-December.

Or, better, use the Month enum objects pre-defined, one for each month of the year. Tip: Use these Month objects throughout your codebase rather than a mere integer number to make your code more self-documenting, ensure valid values, and provide type-safety. Ditto for Year & YearMonth.

LocalDate ld = LocalDate.of( 1986 , Month.FEBRUARY , 23 ) ;

Table of Java date-time types, both modern and legacy.

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.

Where to obtain the java.time classes?

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

Upvotes: 9

Anish B.
Anish B.

Reputation: 16589

"Deprecated" refers to functions or elements that are in the process of being replaced by newer ones. Deprecated items may work in the current version of a programming language, they may not function in future updates.

But you can ignore and use it.

Example : 

String pattern = "yyyy-MM-dd";
SimpleDateFormat simpleDateFormat = new SimpleDateFormat(pattern);
String date = simpleDateFormat.format(new Date(1,1,1));
System.out.println(date);

Output : 

1901-02-01

But if you don't want to use deprecated methods, you can go for LocalDate :

LocalDate localDate = LocalDate.of(2019, 1, 1);
DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
String formatted = localDate.format(dateTimeFormatter);
System.out.println(formatted);

Output : 

2019-01-01

Upvotes: 0

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