WorkOnDate.java

package io.github.chrisscientist.date;

import java.text.DateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;

/**
 *
 * @author chris-scientist
 */
public class WorkOnDate {
    
    /**
     * Here it's implemented for France.
     */
    private static Locale locale = new Locale("fr", "FR");
    
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // Compute dates
        Date today = new Date();
        Date nextDay = buildDateFromToday(1, 0, 0);
        Date previousDays = buildDateFromToday(-1, 0, 0);
        Date previousDaysFor20200401 = buildDate(1, 3 /* for april */, 2020, -1, 0, 0);
        // Show date
        System.out.println("Previous day is " + showDateAsOfLocale(previousDays));
        System.out.println("Today is " + showDateAsOfLocale(today));
        System.out.println("Next day is " + showDateAsOfLocale(nextDay));
        System.out.println("");
        System.out.println("Previous days for 01/04/2020 is " + showDateAsOfLocale(previousDaysFor20200401));
    }
    
    private static Date buildDateFromToday(int days, int months, int years) {
        Date currentDate = new Date();
        
        return buildDateFromOtherDate(currentDate, days, months, years);
    }
    
    private static Date buildDate(int dayOfDate, int monthOfDate, int yearOfDate, int days, int months, int years) {
        Calendar c = new GregorianCalendar(yearOfDate,monthOfDate,dayOfDate);
        
        return buildDateFromOtherDate(c.getTime(), days, months, years);
    }
    
    private static Date buildDateFromOtherDate(Date aDate, int days, int months, int years) {
        Calendar c = Calendar.getInstance();
        c.setTime(aDate);

        c.add(Calendar.YEAR, years);
        c.add(Calendar.MONTH, months);
        c.add(Calendar.DATE, days);

        return c.getTime();
    }
    
    private static String showDateAsOfLocale(Date aDate) {
        DateFormat dateFormat = DateFormat.getDateInstance(DateFormat.DEFAULT, locale);
        return dateFormat.format(aDate);
    }
    
}