How to determine the date one day prior to a given

问题:

I am assuming Java has some built-in way to do this.

Given a date, how can I determine the date one day prior to that date?

For example, suppose I am given 3/1/2009. The previous date is 2/28/2009. If I had been given 3/1/2008, the previous date would have been 2/29/2008.

回答1:

Use the Calendar interface.

Calendar cal = Calendar.getInstance();
cal.setTime(myDate);
cal.add(Calendar.DAY_OF_YEAR,-1);
Date oneDayBefore= cal.getTime();

Doing "addition" in this way guarantees you get a valid date. This is valid for 1st of the year as well, e.g. if myDate is January 1st, 2012, oneDayBefore will be December 31st, 2011.

回答2:

You can also use Joda-Time, a very good Java library to manipulate dates:

DateTime result = dt.minusDays(1);

回答3:

The java.util.Calendar class allows us to add or subtract any number of day/weeks/months/whatever from a date. Just use the add() method:

http://java.sun.com/j2se/1.5.0/docs/api/java/util/Calendar.html

Example:

Calendar date = new GregorianCalendar(2009, 3, 1);
date.add(Calendar.DATE, -1);

回答4:

With java.time.Instant

Date.from(Instant.now().minus(Duration.ofDays(1)))

回答5:

import java.util.Calendar;
import java.util.GregorianCalendar;
import static java.util.Calendar.*;


public class TestDayBefore {

    public static void main(String... args) {
        Calendar calendar = GregorianCalendar.getInstance();
        calendar.set(YEAR, 2009);
        calendar.set(MONTH, MARCH);
        calendar.set(DAY_OF_MONTH, 1);
        System.out.println(calendar.getTime()); //prints Sun Mar 01 23:20:20 EET 2009
        calendar.add(DAY_OF_MONTH, -1);
        System.out.println(calendar.getTime()); //prints Sat Feb 28 23:21:01 EET 2009

    }
}

回答6:

With the date4j library :

DateTime yesterday = today.minusDays(1);

回答7:

This would help.

getPreviousDateForGivenDate("2015-01-19", 10);
getPreviousDateForGivenDate("2015-01-19", -10);

public static String getPreviousDateForGivenDate(String givenDate, int datesPriorOrAfter) {
    String saleDate = getPreviousDate(datesPriorOrAfter);

    try {
        DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
        String[] arr = givenDate.split("-", 3);
        Calendar cal = new GregorianCalendar(Integer.parseInt(arr[0]), Integer.parseInt(arr[1])-1, Integer.parseInt(arr[2]));
        cal.add(Calendar.DAY_OF_YEAR, datesPriorOrAfter);    
        saleDate = dateFormat.format(cal.getTime());

    } catch (Exception e) {
        System.out.println("Error at getPreviousDateForGivenDate():"+e.getMessage());
    }

    return saleDate;
}